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Yan L, Lai HY, Leung TCN, Cheng HF, Chen X, Tsui SKW, Ngai SM, Au SWN. PE/PPE Proteome and ESX-5 Substrate Spectrum in Mycobacterium marinum. Int J Mol Sci 2024; 25:9550. [PMID: 39273496 PMCID: PMC11395111 DOI: 10.3390/ijms25179550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Revised: 08/05/2024] [Accepted: 08/07/2024] [Indexed: 09/15/2024] Open
Abstract
PE/PPE proteins secreted by the ESX-5 type VII secretion system constitute a major protein repertoire in pathogenic mycobacteria and are essential for bacterial survival, pathogenicity, and host-pathogen interaction; however, little is known about their expression and secretion. The scarcity of arginine and lysine residues in PE/PPE protein sequences and the high homology of their N-terminal domains limit protein identification using classical trypsin-based proteomic methods. This study used endoproteinase AspN and trypsin to characterize the proteome of Mycobacterium marinum. Twenty-seven PE/PPE proteins were uniquely identified in AspN digests, especially PE_PGRS proteins. These treatments allowed the identification of approximately 50% of the PE/PPE pool encoded in the genome. Moreover, EspG5 pulldown assays retrieved 44 ESX-5-associated PPE proteins, covering 85% of the PPE pool in the identified proteome. The identification of PE/PE_PGRS proteins in the EspG5 interactome suggested the presence of PE-PPE pairs. The correlation analysis between protein abundance and phylogenetic relationships found potential PE/PPE pairs, indicating the presence of multiple PE/PE_PGRS partners in one PPE. We validated that EspG5 interacted with PPE31 and PPE32 and mapped critical residues for complex formation. The modified proteomic platform increases the coverage of PE/PPE proteins and elucidates the expression and localization of these proteins.
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Affiliation(s)
- Lili Yan
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Hiu Ying Lai
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Thomas Chun Ning Leung
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Hiu Fu Cheng
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Xin Chen
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Stephen Kwok Wing Tsui
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Sai Ming Ngai
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
| | - Shannon Wing Ngor Au
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China
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Trinidad DD, Macdonald CB, Rosenberg OS, Fraser JS, Coyote-Maestas W. Deep mutational scanning of EccD 3 reveals the molecular basis of its essentiality in the mycobacterium ESX secretion system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.23.609456. [PMID: 39229178 PMCID: PMC11370616 DOI: 10.1101/2024.08.23.609456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Tuberculosis remains the deadliest infectious disease in the world and requires novel therapeutic targets. The ESX-3 secretion system, which is essential for iron and zinc homeostasis and thus M. tuberculosis survival, is a promising target. In this study, we perform a deep mutational scan on the ESX-3 core protein EccD3 in the model organism M. smegmatis. We systematically investigated the functional roles of 145 residues across the soluble ubiquitin-like domain, the conformationally distinct flexible linker, and selected transmembrane helices of EccD3. Our data combined with structural comparisons to ESX-5 complexes support a model where EccD3 stabilizes the complex, with the hinge motif within the linker being particularly sensitive to disruption. Our study is the first deep mutational scan in mycobacteria, which could help guide drug development toward novel treatment of tuberculosis. This study underscores the importance of context-specific mutational analyses for discovering essential protein interactions within mycobacterial systems.
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Affiliation(s)
| | - Christian B Macdonald
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Oren S Rosenberg
- Department of Medicine, University of California, San Francisco
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - James S Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Willow Coyote-Maestas
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Quantitative Biosciences Institute, University of California, San Francisco, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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3
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Wynn EA, Dide-Agossou C, Mubarak RA, Rossmassler K, Ektnitphong V, Bauman AA, Massoudi LM, Voskuil MI, Robertson GT, Moore CM, Walter ND. Emergence of antibiotic-specific Mycobacterium tuberculosis phenotypes during prolonged treatment of mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.20.607990. [PMID: 39229030 PMCID: PMC11370397 DOI: 10.1101/2024.08.20.607990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
A major challenge in tuberculosis (TB) therapeutics is that antibiotic exposure leads to changes in the physiologic state of M. tuberculosis (Mtb) which may enable the pathogen to withstand treatment. While antibiotic-treated Mtb have been evaluated in short-term in vitro experiments, it is unclear if and how long-term in vivo treatment with diverse antibiotics with varying treatment-shortening activity (sterilizing activity) affect Mtb physiologic states differently. Here, we used SEARCH-TB, a pathogen-targeted RNA-sequencing platform, to characterize the Mtb transcriptome in the BALB/c high-dose aerosol infection mouse model following 4-week treatment with three sterilizing and three non-sterilizing antibiotics. Certain transcriptional changes were concordant among most antibiotics, including decreased expression of genes associated with protein synthesis and metabolism, and the induction of certain genes associated with stress responses. However, the magnitude of this concordant response differed between antibiotics. Sterilizing antibiotics rifampin, pyrazinamide, and bedaquiline generated a more quiescent Mtb state than did non-sterilizing antibiotics isoniazid, ethambutol, and streptomycin, as indicated by decreased expression of genes associated with translation, transcription, secretion of immunogenic proteins, metabolism, and cell wall synthesis. Additionally, we identified distinguishing transcriptional effects specific to each antibiotic, indicating that different mechanisms of action induce distinct patterns of cellular injury. In addition to elucidating Mtb physiologic changes associated with antibiotic stress, this study demonstrates the value of SEARCH-TB as a highly granular pharmacodynamic assay that reveals antibiotic effects that are not apparent based on culture alone.
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Affiliation(s)
- Elizabeth A Wynn
- Rocky Mountain Regional VA Medical Center, Aurora, CO, USA
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, USA
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
| | - Christian Dide-Agossou
- Rocky Mountain Regional VA Medical Center, Aurora, CO, USA
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Reem Al Mubarak
- Rocky Mountain Regional VA Medical Center, Aurora, CO, USA
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Karen Rossmassler
- Rocky Mountain Regional VA Medical Center, Aurora, CO, USA
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Linda Crnic Institute for Down syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Victoria Ektnitphong
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Allison A Bauman
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Lisa M Massoudi
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Martin I Voskuil
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Gregory T Robertson
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Camille M Moore
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, USA
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Department of Biostatistics and Informatics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Nicholas D Walter
- Rocky Mountain Regional VA Medical Center, Aurora, CO, USA
- Consortium for Applied Microbial Metrics, Aurora, CO, USA
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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4
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Pidot SJ, Klatt S, Ates LS, Frigui W, Sayes F, Majlessi L, Izumi H, Monk IR, Porter JL, Bennett-Wood V, Seemann T, Otter A, Taiaroa G, Cook GM, West N, Tobias NJ, Fuerst JA, Stutz MD, Pellegrini M, McConville M, Brosch R, Stinear TP. Marine sponge microbe provides insights into evolution and virulence of the tubercle bacillus. PLoS Pathog 2024; 20:e1012440. [PMID: 39207937 PMCID: PMC11361433 DOI: 10.1371/journal.ppat.1012440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/22/2024] [Indexed: 09/04/2024] Open
Abstract
Reconstructing the evolutionary origins of Mycobacterium tuberculosis, the causative agent of human tuberculosis, has helped identify bacterial factors that have led to the tubercle bacillus becoming such a formidable human pathogen. Here we report the discovery and detailed characterization of an exceedingly slow growing mycobacterium that is closely related to M. tuberculosis for which we have proposed the species name Mycobacterium spongiae sp. nov., (strain ID: FSD4b-SM). The bacterium was isolated from a marine sponge, taken from the waters of the Great Barrier Reef in Queensland, Australia. Comparative genomics revealed that, after the opportunistic human pathogen Mycobacterium decipiens, M. spongiae is the most closely related species to the M. tuberculosis complex reported to date, with 80% shared average nucleotide identity and extensive conservation of key M. tuberculosis virulence factors, including intact ESX secretion systems and associated effectors. Proteomic and lipidomic analyses showed that these conserved systems are functional in FSD4b-SM, but that it also produces cell wall lipids not previously reported in mycobacteria. We investigated the virulence potential of FSD4b-SM in mice and found that, while the bacteria persist in lungs for 56 days after intranasal infection, no overt pathology was detected. The similarities with M. tuberculosis, together with its lack of virulence, motivated us to investigate the potential of FSD4b-SM as a vaccine strain and as a genetic donor of the ESX-1 genetic locus to improve BCG immunogenicity. However, neither of these approaches resulted in superior protection against M. tuberculosis challenge compared to BCG vaccination alone. The discovery of M. spongiae adds to our understanding of the emergence of the M. tuberculosis complex and it will be another useful resource to refine our understanding of the factors that shaped the evolution and pathogenesis of M. tuberculosis.
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Affiliation(s)
- Sacha J. Pidot
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Stephan Klatt
- Department of Molecular Biology and Biochemistry, Bio21 Institute, University of Melbourne, Parkville, Australia
| | - Louis S. Ates
- Institut Pasteur, Université Paris Cité, Unit for Integrated Mycobacterial Pathogenomics, Paris, France
| | - Wafa Frigui
- Institut Pasteur, Université Paris Cité, Unit for Integrated Mycobacterial Pathogenomics, Paris, France
| | - Fadel Sayes
- Institut Pasteur, Université Paris Cité, Unit for Integrated Mycobacterial Pathogenomics, Paris, France
| | - Laleh Majlessi
- Institut Pasteur, Université Paris Cité, Unit for Integrated Mycobacterial Pathogenomics, Paris, France
| | - Hiroshi Izumi
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Ian R. Monk
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Jessica L. Porter
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Vicki Bennett-Wood
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Torsten Seemann
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Ashley Otter
- UK Health Security Agency, Porton Down, Salisbury, United Kingdom
| | - George Taiaroa
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Gregory M. Cook
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Nicholas West
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Nicholas J. Tobias
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - John A. Fuerst
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Michael D. Stutz
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Marc Pellegrini
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Malcolm McConville
- Department of Molecular Biology and Biochemistry, Bio21 Institute, University of Melbourne, Parkville, Australia
| | - Roland Brosch
- Institut Pasteur, Université Paris Cité, Unit for Integrated Mycobacterial Pathogenomics, Paris, France
| | - Timothy P. Stinear
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
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5
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Chekesa B, Singh H, Gonzalez-Juarbe N, Vashee S, Wiscovitch-Russo R, Dupont CL, Girma M, Kerro O, Gumi B, Ameni G. Pangenome and genomic signatures linked to the dominance of the lineage-4 of Mycobacterium tuberculosis isolated from extrapulmonary tuberculosis patients in western Ethiopia. PLoS One 2024; 19:e0304060. [PMID: 39052555 PMCID: PMC11271921 DOI: 10.1371/journal.pone.0304060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 05/06/2024] [Indexed: 07/27/2024] Open
Abstract
BACKGROUND The lineage 4 (L4) of Mycobacterium tuberculosis (MTB) is not only globally prevalent but also locally dominant, surpassing other lineages, with lineage 2 (L2) following in prevalence. Despite its widespread occurrence, factors influencing the expansion of L4 and its sub-lineages remain poorly understood both at local and global levels. Therefore, this study aimed to conduct a pan-genome and identify genomic signatures linked to the elevated prevalence of L4 sublineages among extrapulmonary TB (EPTB) patients in western Ethiopia. METHODS A cross-sectional study was conducted at an institutional level involving confirmed cases of extrapulmonary tuberculosis (EPTB) patients from August 5, 2018, to December 30, 2019. A total of 75 MTB genomes, classified under lineage 4 (L4), were used for conducting pan-genome and genome-wide association study (GWAS) analyses. After a quality check, variants were identified using MTBseq, and genomes were de novo assembled using SPAdes. Gene prediction and annotation were performed using Prokka. The pan-genome was constructed using GET_HOMOLOGUES, and its functional analysis was carried out with the Bacterial Pan-Genome Analysis tool (BPGA). For GWAS analysis, Scoary was employed with Benjamini-Hochberg correction, with a significance threshold set at p-value ≤ 0.05. RESULTS The analysis revealed a total of 3,270 core genes, predominantly associated with orthologous groups (COG) functions, notably in the categories of '[R] General function prediction only' and '[I] Lipid transport and metabolism'. Conversely, functions related to '[N] Cell motility' and '[Q] Secondary metabolites biosynthesis, transport, and catabolism' were primarily linked to unique and accessory genes. The pan-genome of MTB L4 was found to be open. Furthermore, the GWAS study identified genomic signatures linked to the prevalence of sublineages L4.6.3 and L4.2.2.2. CONCLUSIONS Apart from host and environmental factors, the sublineage of L4 employs distinct virulence factors for successful dissemination in western Ethiopia. Given that the functions of these newly identified genes are not well understood, it is advisable to experimentally validate their roles, particularly in the successful transmission of specific L4 sublineages over others.
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Affiliation(s)
- Basha Chekesa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- Collage of Natural and Computational Science, Wallaga University, Nekemte, Ethiopia
| | - Harinder Singh
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | | | - Sanjay Vashee
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | | | | | - Musse Girma
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Oudessa Kerro
- Institute of Agriculture, The University of Tennessee, Tennessee, Knoxville, United States of America
| | - Balako Gumi
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Gobena Ameni
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- College of Agriculture and Veterinary Medicine, United Arab Emirates University, Al Ain, United Arab Emirates
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6
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Miller AH, Marks F, Chan L, Botella H, Schnappinger D, Ehrt S. Interruption of mycothiol synthesis and intracellular redox status impact iron-regulated reporter activation in Mycobacterium smegmatis. Microbiol Spectr 2024; 12:e0048724. [PMID: 38860795 PMCID: PMC11218476 DOI: 10.1128/spectrum.00487-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/04/2024] [Indexed: 06/12/2024] Open
Abstract
Iron scavenging is required for full virulence of mycobacterial pathogens. During infection, the host immune response restricts mycobacterial access to iron, which is essential for bacterial respiration and DNA synthesis. The Mycobacterium tuberculosis iron-dependent regulator (IdeR) responds to changes in iron accessibility by repressing iron-uptake genes when iron is available. In contrast, iron-uptake gene transcription is induced when iron is depleted. The ideR gene is essential in M. tuberculosis and is required for bacterial growth. To further study how iron regulates transcription, wee developed an iron responsive reporter system that relies on an IdeR-regulated promoter to drive Cre and loxP mediated recombination in Mycobacterium smegmatis. Recombination leads to the expression of an antibiotic resistance gene so that mutations that activate the IdeR-regulated promoter can be selected. A transposon library in the background of this reporter system was exposed to media containing iron and hemin, and this resulted in the selection of mutants in the antioxidant mycothiol synthesis pathway. We validated that inactivation of the mycothiol synthesis gene mshA results in increased recombination and increased IdeR-regulated promoter activity in the reporter system. Further, we show that vitamin C, which has been shown to oxidize iron through the Fenton reaction, can decrease promoter activity in the mshA mutant. We conclude that the intracellular redox state balanced by mycothiol can alter IdeR activity in the presence of iron.IMPORTANCEMycobacterium smegmatis is a tractable organism to study mycobacterial gene regulation. We used M. smegmatis to construct a novel recombination-based reporter system that allows for the selection of mutations that deregulate a promoter of interest. Transposon mutagenesis and insertion sequencing (TnSeq) in the recombination reporter strain identified genes that impact iron regulated promoter activity in mycobacteria. We found that the mycothiol synthesis gene mshA is required for IdeR mediated transcriptional regulation by maintaining intracellular redox balance. By affecting the oxidative state of the intracellular environment, mycothiol can modulate iron-dependent transcriptional activity. Taken more broadly, this novel reporter system can be used in combination with transposon mutagenesis to identify genes that are required by Mycobacterium tuberculosis to overcome temporary or local changes in iron availability during infection.
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Affiliation(s)
- Alexandra H Miller
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
- Immunology and Microbial Pathogenesis Graduate Program, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, USA
| | - Frances Marks
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
- Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology Program, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, USA
| | - Luming Chan
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
| | - Helene Botella
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
| | - Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
- Immunology and Microbial Pathogenesis Graduate Program, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, USA
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7
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Luo G, Ming T, Yang L, He L, Tao T, Wang Y. Modulators targeting protein-protein interactions in Mycobacterium tuberculosis. Microbiol Res 2024; 284:127675. [PMID: 38636239 DOI: 10.1016/j.micres.2024.127675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 04/20/2024]
Abstract
Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis), mainly transmitted through droplets to infect the lungs, and seriously affecting patients' health and quality of life. Clinically, anti-TB drugs often entail side effects and lack efficacy against resistant strains. Thus, the exploration and development of novel targeted anti-TB medications are imperative. Currently, protein-protein interactions (PPIs) offer novel avenues for anti-TB drug development, and the study of targeted modulators of PPIs in M. tuberculosis has become a prominent research focus. Furthermore, a comprehensive PPI network has been constructed using computational methods and bioinformatics tools. This network allows for a more in-depth analysis of the structural biology of PPIs and furnishes essential insights for the development of targeted small-molecule modulators. Furthermore, this article provides a detailed overview of the research progress and regulatory mechanisms of PPI modulators in M. tuberculosis, the causative agent of TB. Additionally, it summarizes potential targets for anti-TB drugs and discusses the prospects of existing PPI modulators.
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Affiliation(s)
- Guofeng Luo
- School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Tianqi Ming
- State Key Laboratory of Southwestern Chinese Medicine Resources, Department of Pharmacology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Luchuan Yang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Lei He
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Tao Tao
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Yanmei Wang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China.
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8
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Shankar G, Akhter Y. Stealing survival: Iron acquisition strategies of Mycobacteriumtuberculosis. Biochimie 2024:S0300-9084(24)00142-1. [PMID: 38901792 DOI: 10.1016/j.biochi.2024.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/07/2024] [Accepted: 06/18/2024] [Indexed: 06/22/2024]
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), faces iron scarcity within the host due to immune defenses. This review explores the importance of iron for Mtb and its strategies to overcome iron restriction. We discuss how the host limits iron as an innate immune response and how Mtb utilizes various iron acquisition systems, particularly the siderophore-mediated pathway. The review illustrates the structure and biosynthesis of mycobactin, a key siderophore in Mtb, and the regulation of its production. We explore the potential of targeting siderophore biosynthesis and uptake as a novel therapeutic approach for TB. Finally, we summarize current knowledge on Mtb's iron acquisition and highlight promising directions for future research to exploit this pathway for developing new TB interventions.
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Affiliation(s)
- Gauri Shankar
- Department of Biotechnology, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow, Uttar Pradesh, 226 025, India
| | - Yusuf Akhter
- Department of Biotechnology, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow, Uttar Pradesh, 226 025, India.
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9
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Veerapandian R, Gadad SS, Jagannath C, Dhandayuthapani S. Live Attenuated Vaccines against Tuberculosis: Targeting the Disruption of Genes Encoding the Secretory Proteins of Mycobacteria. Vaccines (Basel) 2024; 12:530. [PMID: 38793781 PMCID: PMC11126151 DOI: 10.3390/vaccines12050530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
Tuberculosis (TB), a chronic infectious disease affecting humans, causes over 1.3 million deaths per year throughout the world. The current preventive vaccine BCG provides protection against childhood TB, but it fails to protect against pulmonary TB. Multiple candidates have been evaluated to either replace or boost the efficacy of the BCG vaccine, including subunit protein, DNA, virus vector-based vaccines, etc., most of which provide only short-term immunity. Several live attenuated vaccines derived from Mycobacterium tuberculosis (Mtb) and BCG have also been developed to induce long-term immunity. Since Mtb mediates its virulence through multiple secreted proteins, these proteins have been targeted to produce attenuated but immunogenic vaccines. In this review, we discuss the characteristics and prospects of live attenuated vaccines generated by targeting the disruption of the genes encoding secretory mycobacterial proteins.
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Affiliation(s)
- Raja Veerapandian
- Center of Emphasis in Infectious Diseases, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
| | - Shrikanth S. Gadad
- Center of Emphasis in Cancer, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
| | - Chinnaswamy Jagannath
- Department of Pathology and Genomic Medicine, Houston Methodist Research Institute & Weill Cornell Medical College, Houston, TX 77030, USA
| | - Subramanian Dhandayuthapani
- Center of Emphasis in Infectious Diseases, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
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10
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Sao Emani C, Reiling N. The efflux pumps Rv1877 and Rv0191 play differential roles in the protection of Mycobacterium tuberculosis against chemical stress. Front Microbiol 2024; 15:1359188. [PMID: 38516013 PMCID: PMC10956863 DOI: 10.3389/fmicb.2024.1359188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 02/12/2024] [Indexed: 03/23/2024] Open
Abstract
Background It was previously shown that GlnA3sc enabled Streptomyces coelicolor to survive in excess polyamines. However, subsequent studies revealed that Rv1878, the corresponding Mycobacterium tuberculosis (M.tb) ortholog, was not essential for the detoxification of spermine (Spm), in M.tb. On the other hand, the multi-drug efflux pump Rv1877 was previously shown to enable export of a wide range of compounds, while Rv0191 was shown to be more specific to chloramphenicol. Rationale Therefore, we first wanted to determine if detoxification of Spm by efflux can be achieved by any efflux pump, or if that was dependent upon the function of the pump. Next, since Rv1878 was found not to be essential for the detoxification of Spm, we sought to follow-up on the investigation of the physiological role of Rv1878 along with Rv1877 and Rv0191. Approach To evaluate the specificity of efflux pumps in the mycobacterial tolerance to Spm, we generated unmarked ∆rv1877 and ∆rv0191 M.tb mutants and evaluated their susceptibility to Spm. To follow up on the investigation of any other physiological roles they may have, we characterized them along with the ∆rv1878 M.tb mutant. Results The ∆rv1877 mutant was sensitive to Spm stress, while the ∆rv0191 mutant was not. On the other hand, the ∆rv1878 mutant grew better than the wild-type during iron starvation yet was sensitive to cell wall stress. The proteins Rv1877 and Rv1878 seemed to play physiological roles during hypoxia and acidic stress. Lastly, the ∆rv0191 mutant was the only mutant that was sensitive to oxidative stress. Conclusion The multidrug MFS-type efflux pump Rv1877 is required for Spm detoxification, as opposed to Rv0191 which seems to play a more specific role. Moreover, Rv1878 seems to play a role in the regulation of iron homeostasis and the reconstitution of the cell wall of M.tb. On the other hand, the sensitivity of the ∆rv0191 mutant to oxidative stress, suggests that Rv0191 may be responsible for the transport of low molecular weight thiols.
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Affiliation(s)
- Carine Sao Emani
- Microbial Interface Biology, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Norbert Reiling
- Microbial Interface Biology, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Borstel, Germany
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11
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Sánchez‐Costa M, Gola S, Rodríguez‐Sáiz M, Barredo J, Hidalgo A, Berenguer J. From accurate genome sequence to biotechnological application: The thermophile Mycolicibacterium hassiacum as experimental model. Microb Biotechnol 2024; 17:e14290. [PMID: 37498289 PMCID: PMC10832570 DOI: 10.1111/1751-7915.14290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 07/28/2023] Open
Abstract
Mycobacteria constitute a large group of microorganisms belonging to the phylum Actinobacteria encompassing some of the most relevant pathogenic bacteria and many saprophytic isolates that share a unique and complex cell envelope. Also unique to this group is the extensive capability to use and synthesize sterols, a class of molecules that include active signalling compounds of pharmaceutical use. However, few mycobacterial species and strains have been established as laboratory models to date, Mycolicibacterium smegmatis mc2 155 being the most common one. In this work, we focus on the use of a thermophilic mycobacterium, Mycolicibacterium hassiacum, which grows optimally above 50°C, as an emerging experimental model valid to extend our general knowledge of mycobacterial biology as well as for application purposes. To that end, accurate genomic sequences are key for gene mining, the study of pathogenicity or lack thereof and the potential for gene transfer. The combination of long- and short-massive sequencing technologies is strictly necessary to remove biases caused by errors specific to long-reads technology. By doing so in M. hassiacum, we obtained from the curated genome clues regarding the genetic manipulation potential of this microorganism from the presence of insertion sequences, CRISPR-Cas, type VII ESX secretion systems, as well as lack of plasmids. Finally, as a proof of concept of the applicability of M. hassiacum as a laboratory and industrial model, we used this high-quality genome of M. hassiacum to successfully knockout a gene involved in the use of phytosterols as source of carbon and energy, using an improved gene cassette for thermostable selection and a transformation protocol at high temperature.
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Affiliation(s)
- Mercedes Sánchez‐Costa
- Department of Molecular Biology, Faculty of SciencesCentre for Molecular Biology (UAM‐CSIC)University Institute for Molecular BiologyMadridSpain
| | - Susanne Gola
- Department of Medical Technology and BiotechnologyErnst‐Abbe‐Hochschule Jena, University of Applied SciencesJenaGermany
| | | | - José‐Luis Barredo
- Department of BiotechnologyCuria, Parque Tecnológico de LeónLeónSpain
| | - Aurelio Hidalgo
- Department of Molecular Biology, Faculty of SciencesCentre for Molecular Biology (UAM‐CSIC)University Institute for Molecular BiologyMadridSpain
| | - José Berenguer
- Department of Molecular Biology, Faculty of SciencesCentre for Molecular Biology (UAM‐CSIC)University Institute for Molecular BiologyMadridSpain
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Sun H, Sheng G, Xu Y, Chu H, Cao T, Dai G, Tian N, Duan H, Sun Z. Efflux pump Rv1258c activates novel functions of the oxidative stress and via the VII secretion system ESX-3-mediated iron metabolic pathway in Mycobacterium tuberculosis. Microbes Infect 2024; 26:105239. [PMID: 37863312 DOI: 10.1016/j.micinf.2023.105239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 10/08/2023] [Accepted: 10/17/2023] [Indexed: 10/22/2023]
Abstract
Oxidative stress and iron metabolism are essential for Mycobacterium tuberculosis (M.tb) survival in host cells. The efflux pump Rv1258c belongs to the major facilitator superfamily (MFS) and can actively pump drugs to promote certain drug resistance in M.tb. In this study, we compared H37RvΔRv1258c with wild-type (WT) M.tb H37Rv. The qRT-PCR results suggested that Rv1258c is potentially involved in the iron metabolic pathway by regulating the expression of ESX-3, which is required for iron uptake. Protein-Protein Affinity Predictor (PPA-Pred2) and the artificial intelligence program AlphaFold 2 were used for prediction and showed that Rv1258c has direct interactions with PPE4 and EccD3 but weak interactions with EccB3. This was further determined via protein-protein interaction analysis of the yeast two-hybrid expression system. By comparing mutant H37RvΔRv1258c strains with WT strains, we discovered that the absence of Rv1258c led to elevated intracellular H+ potential and NAD+/NADH ratios in M.tb, thereby resulting in oxidative stress. We hypothesize that the efflux pump Rv1258c not only has the function of regulating drug resistance in M.tb but also has a novel function in activating oxidative stress and regulating ESX-3-associated iron metabolism in M.tb.
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Affiliation(s)
- Hong Sun
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Gang Sheng
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Yuhui Xu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Science, Beijing 100700, China
| | - Hongqian Chu
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Tingming Cao
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Guangming Dai
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Na Tian
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Huijuan Duan
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China
| | - Zhaogang Sun
- Translational Medicine Center, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China, Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China.
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Granados-Tristán AL, Hernández-Luna CE, González-Escalante LA, Camacho-Moll ME, Silva-Ramírez B, Bermúdez de León M, Peñuelas-Urquides K. ESX-3 secretion system in Mycobacterium: An overview. Biochimie 2024; 216:46-55. [PMID: 37879428 DOI: 10.1016/j.biochi.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 09/26/2023] [Accepted: 10/22/2023] [Indexed: 10/27/2023]
Abstract
Mycobacteria are microorganisms distributed in the environment worldwide, and some of them, such as Mycobacterium tuberculosis or M. leprae, are pathogenic. The hydrophobic mycobacterial cell envelope has low permeation and bacteria need to export products across their structure. Mycobacteria possess specialized protein secretion systems, such as the Early Secretory Antigenic Target 6 secretion (ESX) system. Five ESX loci have been described in M. tuberculosis, called ESX-1 to ESX-5. The ESX-3 secretion system has been associated with mycobacterial metabolism and growth. The locus of this system is highly conserved across mycobacterial species. Metallo-proteins regulate negative ESX-3 transcription in high conditions of iron and zinc. Moreover, this secretion system is part of an antioxidant regulatory pathway linked to Zinc. EccA3, EccB3, EccC3, EccD3, and EccE3 are components of the ESX-3 secretion machinery, whereas EsxG-EsxH, PE5-PPE4, and PE15-PPE20 are proteins secreted by this system. In addition, EspG3 and MycP3 are complementary proteins involved in transport and proteolysis respectively. This system is associated to mycobacterial virulence by releasing the bacteria from the phagosome and inhibiting endomembrane damage response. Furthermore, components of this system inhibit the host immune response by reducing the recognition of M. tuberculosis-infected cells. The components of the ESX-3 secretion system play a role in drug resistance and cell wall integrity. Moreover, the expression data of this system indicated that external and internal factors affect ESX-3 locus expression. This review provides an overview of new findings on the ESX-3 secretion system, its regulation, expression, and functions.
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Affiliation(s)
- Ana Laura Granados-Tristán
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico; Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
| | - Carlos Eduardo Hernández-Luna
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
| | - Laura Adiene González-Escalante
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - María Elena Camacho-Moll
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - Beatriz Silva-Ramírez
- Departamento de Inmunogenética, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - Mario Bermúdez de León
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - Katia Peñuelas-Urquides
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
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Karthik K, Subramanian S, Vinoli Priyadharshini M, Jawahar A, Anbazhagan S, Kathiravan RS, Thomas P, Babu RPA, Gopalan Tirumurugaan K, Raj GD. Whole genome sequencing and comparative genomics of Mycobacterium orygis isolated from different animal hosts to identify specific diagnostic markers. Front Cell Infect Microbiol 2023; 13:1302393. [PMID: 38188626 PMCID: PMC10770871 DOI: 10.3389/fcimb.2023.1302393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/22/2023] [Indexed: 01/09/2024] Open
Abstract
Introduction Mycobacterium orygis, a member of MTBC has been identified in higher numbers in the recent years from animals of South Asia. Comparative genomics of this important zoonotic pathogen is not available which can provide data on the molecular difference between other MTBC members. Hence, the present study was carried out to isolate, whole genome sequence M. orygis from different animal species (cattle, buffalo and deer) and to identify molecular marker for the differentiation of M. orygis from other MTBC members. Methods Isolation and whole genome sequencing of M. orygis was carried out for 9 samples (4 cattle, 4 deer and 1 buffalo) died due to tuberculosis. Comparative genomics employing 53 genomes (44 from database and 9 newly sequenced) was performed to identify SNPs, spoligotype, pangenome structure, and region of difference. Results M. orygis was isolated from water buffalo and sambar deer which is the first of its kind report worldwide. Comparative pangenomics of all M. orygis strains worldwide (n= 53) showed a closed pangenome structure which is also reported for the first time. Pairwise SNP between TANUVAS_2, TANUVAS_4, TANUVAS_5, TANUVAS_7 and NIRTAH144 was less than 15 indicating that the same M. orygis strain may be the cause for infection. Region of difference prediction showed absence of RD7, RD8, RD9, RD10, RD12, RD301, RD315 in all the M. orygis analyzed. SNPs in virulence gene, PE35 was found to be unique to M. orygis which can be used as marker for identification. Conclusion The present study is yet another supportive evidence that M. orygis is more prevalent among animals in South Asia and the zoonotic potential of this organism needs to be evaluated.
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Affiliation(s)
- Kumaragurubaran Karthik
- Department of Veterinary Microbiology, Veterinary College and Research Institute, Tamil Nadu Veterinary and Animal Sciences University, Udumalpet, India
| | - Saraswathi Subramanian
- Translational Research Platform for Veterinary Biologicals, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
| | - Michael Vinoli Priyadharshini
- Translational Research Platform for Veterinary Biologicals, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
| | - Ayyaru Jawahar
- Translational Research Platform for Veterinary Biologicals, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
| | - Subbaiyan Anbazhagan
- Indian Council of Medical Research (ICMR)-National Animal Resource Facility for Biomedical Research, Hyderabad, Telangana, India
| | - Ramaiyan Selvaraju Kathiravan
- Translational Research Platform for Veterinary Biologicals, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
| | - Prasad Thomas
- Division of Bacteriology and Mycology, Indian Council of Agricultural Research (ICAR)- India Veterinary Research Institute, Bareilly, Uttar Pradesh, India
| | - Ramasamy Parthiban Aravindh Babu
- Translational Research Platform for Veterinary Biologicals, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
| | - Krishnaswamy Gopalan Tirumurugaan
- Translational Research Platform for Veterinary Biologicals, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
| | - Gopal Dhinakar Raj
- Department of Animal Biotechnology, Madras Veterinary College, Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, India
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Belardinelli JM, Arora D, Avanzi C, Wheat WH, Bryant JM, Spencer JS, Blundell TL, Parkhill J, Floto RA, Jackson M. Clinically relevant mutations in the PhoR sensor kinase of host-adapted Mycobacterium abscessus isolates impact response to acidic pH and virulence. Microbiol Spectr 2023; 11:e0158823. [PMID: 37874174 PMCID: PMC10715180 DOI: 10.1128/spectrum.01588-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/14/2023] [Indexed: 10/25/2023] Open
Abstract
IMPORTANCE Difficult-to-treat pulmonary infections caused by nontuberculous mycobacteria of the Mycobacterium abscessus group have been steadily increasing in the USA and globally. Owing to the relatively recent recognition of M. abscessus as a human pathogen, basic and translational research to address critical gaps in diagnosis, treatment, and prevention of diseases caused by this microorganism has been lagging behind that of the better-known mycobacterial pathogen, Mycobacterium tuberculosis. To begin unraveling the molecular mechanisms of pathogenicity of M. abscessus, we here focus on the study of a two-component regulator known as PhoPR which we found to be under strong evolutionary pressure during human lung infection. We show that PhoPR is activated at acidic pH and serves to regulate a defined set of genes involved in host adaptation. Accordingly, clinical isolates from chronically infected human lungs tend to hyperactivate this regulator enabling M. abscessus to escape macrophage killing.
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Affiliation(s)
- Juan M Belardinelli
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Divya Arora
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
| | - Charlotte Avanzi
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - William H Wheat
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Josephine M Bryant
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
- University of Cambridge Centre for AI in Medicine , Cambridge, United Kingdom
| | - John S Spencer
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge , Cambridge, United Kingdom
| | - Julian Parkhill
- Wellcome Sanger Institute , Hinxton, United Kingdom
- Department of Veterinary Medicine, University of Cambridge , Cambridge, United Kingdom
| | - R Andres Floto
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
- University of Cambridge Centre for AI in Medicine , Cambridge, United Kingdom
- Cambridge Centre for Lung Infection, Papworth Hospital , Cambridge, United Kingdom
| | - Mary Jackson
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
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16
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Williams JT, Baker JJ, Zheng H, Dechow SJ, Fallon J, Murto M, Albrecht VJ, Gilliland HN, Olive AJ, Abramovitch RB. A genetic selection for Mycobacterium smegmatis mutants tolerant to killing by sodium citrate defines a combined role for cation homeostasis and osmotic stress in cell death. mSphere 2023; 8:e0035823. [PMID: 37681985 PMCID: PMC10597346 DOI: 10.1128/msphere.00358-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/23/2023] [Indexed: 09/09/2023] Open
Abstract
Mycobacteria can colonize environments where the availability of metal ions is limited. Biological or inorganic chelators play an important role in limiting metal availability, and we developed a model to examine Mycobacterium smegmatis survival in the presence of the chelator sodium citrate. We observed that instead of restricting M. smegmatis growth, concentrated sodium citrate killed M. smegmatis. RNAseq analysis during sodium citrate treatment revealed transcriptional signatures of metal starvation and hyperosmotic stress. Notably, metal starvation and hyperosmotic stress, individually, do not kill M. smegmatis under these conditions. A forward genetic transposon selection was conducted to examine why sodium citrate was lethal, and several sodium-citrate-tolerant mutants were isolated. Based on the identity of three tolerant mutants, mgtE, treZ, and fadD6, we propose a dual stress model of killing by sodium citrate, where sodium citrate chelate metals from the cell envelope and then osmotic stress in combination with a weakened cell envelope causes cell lysis. This sodium citrate tolerance screen identified mutants in several other genes with no known function, with most conserved in the pathogen M. tuberculosis. Therefore, this model will serve as a basis to define their functions, potentially in maintaining cell wall integrity, cation homeostasis, or osmotolerance. IMPORTANCE Bacteria require mechanisms to adapt to environments with differing metal availability. When Mycobacterium smegmatis is treated with high concentrations of the metal chelator sodium citrate, the bacteria are killed. To define the mechanisms underlying killing by sodium citrate, we conducted a genetic selection and observed tolerance to killing in mutants of the mgtE magnesium transporter. Further characterization studies support a model where killing by sodium citrate is driven by a weakened cell wall and osmotic stress, that in combination cause cell lysis.
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Affiliation(s)
- John T. Williams
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Jacob J. Baker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Huiqing Zheng
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Shelby J. Dechow
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Jared Fallon
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Megan Murto
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Veronica J. Albrecht
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Haleigh N. Gilliland
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Andrew J. Olive
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Robert B. Abramovitch
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
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Kumar G, Adhikrao PA. Targeting Mycobacterium tuberculosis iron-scavenging tools: a recent update on siderophores inhibitors. RSC Med Chem 2023; 14:1885-1913. [PMID: 37859726 PMCID: PMC10583813 DOI: 10.1039/d3md00201b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 08/22/2023] [Indexed: 10/21/2023] Open
Abstract
Among the various bacterial infections, tuberculosis (TB) remains a life-threatening infectious disease responsible as the most significant cause of mortality and morbidity worldwide. The co-infection of human immunodeficiency virus (HIV) in association with TB burdens the healthcare system substantially. Notably, M.tb possesses defence against most antitubercular antibiotic drugs, and the efficacy of existing frontline anti-TB drugs is waning. Also, new and recurring cases of TB from resistant bacteria such as multidrug-resistant TB (MDR), extensively drug-resistant TB (XDR), and totally drug-resistant TB (TDR) strains are increasing. Hence, TB begs the scientific community to explore the new therapeutic class of compounds with their novel mechanism. M.tb requires iron from host cells to sustain, grow, and carry out several biological processes. M.tb has developed strategic methods of acquiring iron from the surrounding environment. In this communication, we discuss an overview of M.tb iron-scavenging tools. Also, we have summarized recently identified MbtA and MbtI inhibitors, which prevent M.tb from scavenging iron. These iron-scavenging tool inhibitors have the potential to be developed as anti-TB agents/drugs.
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Affiliation(s)
- Gautam Kumar
- Department of Natural Products, Chemical Sciences, National Institute of Pharmaceutical Education and Research-Hyderabad (NIPER-Hyderabad) Balanagar Hyderabad 500037 India
| | - Patil Amruta Adhikrao
- Department of Natural Products, Chemical Sciences, National Institute of Pharmaceutical Education and Research-Hyderabad (NIPER-Hyderabad) Balanagar Hyderabad 500037 India
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Liu W, Cen H, Wu Z, Zhou H, Chen S, Yang X, Zhao G, Zhang G. Mycobacteriaceae Phenome Atlas (MPA): A Standardized Atlas for the Mycobacteriaceae Phenome Based on Heterogeneous Sources. PHENOMICS (CHAM, SWITZERLAND) 2023; 3:439-456. [PMID: 37881319 PMCID: PMC10593683 DOI: 10.1007/s43657-023-00101-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 02/23/2023] [Accepted: 03/03/2023] [Indexed: 10/27/2023]
Abstract
The bacterial family Mycobacteriaceae includes pathogenic and nonpathogenic bacteria, and systematic research on their genome and phenome can give comprehensive perspectives for exploring their disease mechanism. In this study, the phenotypes of Mycobacteriaceae were inferred from available phenomic data, and 82 microbial phenotypic traits were recruited as data elements of the microbial phenome. This Mycobacteriaceae phenome contains five categories and 20 subcategories of polyphasic phenotypes, and three categories and eight subcategories of functional phenotypes, all of which are complementary to the existing data standards of microbial phenotypes. The phenomic data of Mycobacteriaceae strains were compiled by literature mining, third-party database integration, and bioinformatics annotation. The phenotypes were searchable and comparable from the website of the Mycobacteriaceae Phenome Atlas (MPA, https://www.biosino.org/mpa/). A topological data analysis of MPA revealed the co-evolution between Mycobacterium tuberculosis and virulence factors, and uncovered potential pathogenicity-associated phenotypes. Two hundred and sixty potential pathogen-enriched pathways were found by Fisher's exact test. The application of MPA may provide novel insights into the pathogenicity mechanism and antimicrobial targets of Mycobacteriaceae. Supplementary Information The online version contains supplementary material available at 10.1007/s43657-023-00101-5.
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Affiliation(s)
- Wan Liu
- National Genomics Data Center & Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Hui Cen
- National Genomics Data Center & Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Zhile Wu
- National Genomics Data Center & Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
- Shanghai Southgene Technology Co., Ltd., Shanghai, 201210 China
| | - Haokui Zhou
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055 China
| | - Shuo Chen
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055 China
| | - Xilan Yang
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055 China
| | - Guoping Zhao
- National Genomics Data Center & Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024 China
| | - Guoqing Zhang
- National Genomics Data Center & Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
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Allué-Guardia A, Garcia-Vilanova A, Schami AM, Olmo-Fontánez AM, Hicks A, Peters J, Maselli DJ, Wewers MD, Wang Y, Torrelles JB. Exposure of Mycobacterium tuberculosis to human alveolar lining fluid shows temporal and strain-specific adaptation to the lung environment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.27.559381. [PMID: 37808780 PMCID: PMC10557635 DOI: 10.1101/2023.09.27.559381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Upon infection, Mycobacterium tuberculosis ( M.tb ) reaches the alveolar space and comes in close contact with human alveolar lining fluid (ALF) for an uncertain period of time prior to its encounter with alveolar cells. We showed that homeostatic ALF hydrolytic enzymes modify the M.tb cell envelope, driving M.tb -host cell interactions. Still, the contribution of ALF during M.tb infection is poorly understood. Here, we exposed 4 M.tb strains with different levels of virulence, transmissibility, and drug resistance (DR) to physiological concentrations of human ALF for 15-min and 12-h, and performed RNA sequencing. Gene expression analysis showed a temporal and strain-specific adaptation to human ALF. Differential expression (DE) of ALF-exposed vs. unexposed M.tb revealed a total of 397 DE genes associated with lipid metabolism, cell envelope and processes, intermediary metabolism and respiration, and regulatory proteins, among others. Most DE genes were detected at 12-h post-ALF exposure, with DR- M.tb strain W-7642 having the highest number of DE genes. Interestingly, genes from the KstR2 regulon, which controls the degradation of cholesterol C and D rings, were significantly upregulated in all strains post-ALF exposure. These results indicate that M.tb -ALF contact drives initial metabolic and physiologic changes in M.tb , with potential implications in infection outcome. IMPORTANCE Tuberculosis, caused by airborne pathogen Mycobacterium tuberculosis ( M.tb ), is one of the leading causes of mortality worldwide. Upon infection, M.tb reaches the alveoli and gets in contact with human alveolar lining fluid (ALF), where ALF hydrolases modify the M.tb cell envelope driving subsequent M.tb -host cell interactions. Still, the contributions of ALF during infection are poorly understood. We exposed 4 M.tb strains to ALF for 15-min and 12-h and performed RNA sequencing, demonstrating a temporal and strain-specific adaptation of M.tb to ALF. Interestingly, genes associated with cholesterol degradation were highly upregulated in all strains. This study shows for the first time that ALF drives global metabolic changes in M.tb during the initial stages of the infection, with potential implications in disease outcome. Biologically relevant networks and common and strain-specific bacterial determinants derived from this study could be further investigated as potential therapeutic candidates.
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Li X, Chen L, Wang Y, Guo X, He ZG. Zinc excess impairs Mycobacterium bovis growth through triggering a Zur-IdeR-iron homeostasis signal pathway. Microbiol Spectr 2023; 11:e0106923. [PMID: 37668384 PMCID: PMC10580935 DOI: 10.1128/spectrum.01069-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/15/2023] [Indexed: 09/06/2023] Open
Abstract
Zinc excess is toxic to bacteria and, thus, represents an important innate defense mechanism of host cells, especially against mycobacterial infections. However, the signaling pathway triggered by zinc excess and its relationship with iron homeostasis remain poorly understood in mycobacteria. Here, we characterize a novel Zur-IdeR-iron homeostasis signaling pathway that modulates the growth of Mycobacterium bovis under zinc toxicity. We found that the regulator Zur interacts with the iron-homeostasis regulator IdeR, enhancing the DNA-binding ability of IdeR. Excess zinc disrupts this interaction and represses ideR transcription through Zur, which promotes the expression of iron uptake genes and leads to the accumulation of intracellular iron in M. bovis. The elevated iron levels lower the bacterial survival ability under excess zinc stress. Consistently, deleting zur hinders intracellular iron accumulation of M. bovis and enhances bacterial growth under stress, while silencing ideR impairs the growth of the wild-type and zur-deleted strains under the same conditions. Interestingly, both Zur and IdeR are conserved in bacteria facing zinc toxicity. Overall, our work uncovers a novel antimicrobial signal pathway whereby zinc excess disrupts iron homeostasis, which may deepen our understanding of the crosstalk mechanism between iron and zinc homeostasis in bacteria.IMPORTANCEAs a catalytic and structural cofactor of proteins, zinc is essential for almost all living organisms. However, zinc excess is toxic and represents a vital innate immunity strategy of macrophages to combat intracellular pathogens, especially against mycobacterial pathogens such as Mycobacterium tuberculosis, the causative agent of tuberculosis. Here, we first characterize an antibacterial signaling pathway of zinc excess and its relationship with iron homeostasis in M. bovis. We found that excess zinc inhibits the transcription of ideR and its DNA-binding activity through Zur, which, in turn, promotes the expression of iron uptake genes, causes intracellular iron accumulation, and finally impairs the bacterial growth. This study reveals the existence of the Zur-IdeR-iron homeostasis pathway triggered by zinc excess in M. bovis, which will shed light on the crosstalk mechanisms between zinc and iron homeostasis in bacteria and the antimicrobial mechanisms of host-mediated zinc toxicity.
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Affiliation(s)
- Xiaohui Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Liu Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yuankun Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Xiao Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Zheng-Guo He
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
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21
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Krishnan V, Nath S, Nair P, Das B. Mycobacterium tuberculosis and its clever approaches to escape the deadly macrophage. World J Microbiol Biotechnol 2023; 39:300. [PMID: 37667129 DOI: 10.1007/s11274-023-03735-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 08/19/2023] [Indexed: 09/06/2023]
Abstract
Mycobacterium tuberculosis (Mt.b), a deadly disease causer, is a facultative parasite. This microorganism has developed several methods to defend itself, once internalized within specialised vacuoles in the macrophages. A wide array of receptors like the complement receptor mannose receptors, scavenger receptor assists the entry of the microbe within the phagocytic macrophages. However, Mt.b is clever enough to protect itself from the hostile environment of the macrophage thereby prevailing within it. The microbe can efficiently inhibit processes like phagosome-lysosome fusion, acidification of phagosomes, release of proinflammatory cytokines and stop crucial events like apoptosis. Additionally, it also adopts resistance to killing by reactive oxygen intermediates and reactive nitrogen intermediates. There are multiple genes both in host and the pathogen which are involved in this successful survival of Mt.b. The regulation of phagolysosome fusion is mediated by proteins such as Coronin, TlyA, SapM, PnkG, EsxH. The microbe has certain mechanisms to even acquire iron from the host cell, to withstand iron deprivation as a mode of host's defence mechanism. This review focuses on the various defensive adaptations acquired by Mt.b for fighting against the deprived conditions existing within the macrophages and their capability of proliferating successfully within it, thereby resulting in a diseased condition.
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Affiliation(s)
- Vinaya Krishnan
- Department of Biotechnology, Mount Carmel College Autonomous, Bengaluru, 560052, India
| | | | - Preetha Nair
- Department of Biotechnology, Mount Carmel College Autonomous, Bengaluru, 560052, India
| | - Bannhi Das
- Department of Biotechnology, Mount Carmel College Autonomous, Bengaluru, 560052, India.
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22
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de Miranda R, Cuthbert BJ, Klevorn T, Chao A, Mendoza J, Arbing M, Sieminski PJ, Papavinasasundaram K, Abdul-Hafiz S, Chan S, Sassetti CM, Ehrt S, Goulding CW. Differentiating the roles of Mycobacterium tuberculosis substrate binding proteins, FecB and FecB2, in iron uptake. PLoS Pathog 2023; 19:e1011650. [PMID: 37747938 PMCID: PMC10553834 DOI: 10.1371/journal.ppat.1011650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 10/05/2023] [Accepted: 08/31/2023] [Indexed: 09/27/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, poses a great threat to human health. With the emergence of drug resistant Mtb strains, new therapeutics are desperately needed. As iron is critical to the growth and survival of Mtb, mechanisms through which Mtb acquires host iron represent attractive therapeutic targets. Mtb scavenges host iron via Mtb siderophore-dependent and heme iron uptake pathways. While multiple studies describe the import of heme and ferric-siderophores and the export of apo-siderophores across the inner membrane, little is known about their transport across the periplasm and cell-wall environments. Mtb FecB and FecB2 are predicted periplasmic binding proteins implicated in host iron acquisition; however, their precise roles are not well understood. This study sought to differentiate the roles FecB and FecB2 play in Mtb iron acquisition. The crystallographic structures of Mtb FecB and FecB2 were determined to 2.0 Å and 2.2 Å resolution, respectively, and show distinct ligand binding pockets. In vitro ligand binding experiments for FecB and FecB2 were performed with heme and bacterial siderophores from Mtb and other species, revealing that both FecB and FecB2 bind heme, while only FecB binds the Mtb sideophore ferric-carboxymycobactin (Fe-cMB). Subsequent structure-guided mutagenesis of FecB identified a single glutamate residue-Glu339-that significantly contributes to Fe-cMB binding. A role for FecB in the Mtb siderophore-mediated iron acquisition pathway was corroborated by Mycobacterium smegmatis and Mtb pull-down assays, which revealed interactions between FecB and members of the mycobacterial siderophore export and import machinery. Similarly, pull-down assays with FecB2 confirms its role in heme uptake revealing interactions with a potential inner membrane heme importer. Due to ligand preference and protein partners, our data suggest that Mtb FecB plays a role in siderophore-dependent iron and heme acquisition pathways; in addition, we confirm that Mtb FecB2 is involved in heme uptake.
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Affiliation(s)
- Rodger de Miranda
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Bonnie J. Cuthbert
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Thaís Klevorn
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Alex Chao
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Jessica Mendoza
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Mark Arbing
- UCLA-DOE Institute, UCLA, Los Angeles, Calofornia, United States of America
| | - Paul J. Sieminski
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Kadamba Papavinasasundaram
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Sumer Abdul-Hafiz
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Sum Chan
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Christopher M. Sassetti
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Celia W. Goulding
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, Califiornia, United States of America
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23
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Li B, He S, Tan Z, Li A, Fan J, Zhao L, Zhang Z, Chu H. Impaired ESX-3 Induces Bedaquiline Persistence in Mycobacterium abscessus Growing Under Iron-Limited Conditions. SMALL METHODS 2023; 7:e2300183. [PMID: 37291735 DOI: 10.1002/smtd.202300183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 05/15/2023] [Indexed: 06/10/2023]
Abstract
ESX-3 is a secretion pathway which is essential for mycobactin-mediated iron acquisition under iron-limited conditions. Although present in all Mycobacterium sp., ESX-3 remains to be elucidated in Mycobacterium abscessus. In the study reported here, impaired ESX-3 seriously restricts the growth of M. abscesses under iron-limited conditions; growth is salvaged by functional ESX-3 or iron supplementation. Notably, impaired ESX-3 does not kill M. abscesses when environmental iron is insufficient but induces persistence to bedaquiline, a diarylquinoline class antibiotic used to treat multidrug-resistant mycobacteria. One potential mechanism contributing to persistence is the iron deficiency due to impaired ESX-3 suppressing succinate dehydrogenase activity, which dysregulates the tricarboxylic acid cycle and inactivates bedaquiline. Experiments conducted here also demonstrate that the regulator, MtrA, can bind ESX-3 and promote the survival of M. abscessus. As such, this study suggests that a novel pathway involving MtrA, ESX-3, iron metabolism, and the TCA cycle contributes to bedaquiline persistence in M. abscesses growing under iron-limited conditions.
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Affiliation(s)
- Bing Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Siyuan He
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Zhili Tan
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Anqi Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Junsheng Fan
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Lan Zhao
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Zhemin Zhang
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Haiqing Chu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
- Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
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24
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Nelson SJ, Williams JT, Buglino JA, Nambi S, Lojek LJ, Glickman MS, Ioerger TR, Sassetti CM. The Rip1 intramembrane protease contributes to iron and zinc homeostasis in Mycobacterium tuberculosis. mSphere 2023; 8:e0038922. [PMID: 37318217 PMCID: PMC10449499 DOI: 10.1128/msphere.00389-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 04/28/2023] [Indexed: 06/16/2023] Open
Abstract
Mycobacterium tuberculosis is exposed to a variety of stresses during a chronic infection, as the immune system simultaneously produces bactericidal compounds and starves the pathogen of essential nutrients. The intramembrane protease, Rip1, plays an important role in the adaptation to these stresses, at least partially by the cleavage of membrane-bound transcriptional regulators. Although Rip1 is known to be critical for surviving copper intoxication and nitric oxide exposure, these stresses do not fully account for the regulatory protein's essentiality during infection. In this work, we demonstrate that Rip1 is also necessary for growth in low-iron and low-zinc conditions, similar to those imposed by the immune system. Using a newly generated library of sigma factor mutants, we show that the known regulatory target of Rip1, SigL, shares this defect. Transcriptional profiling under iron-limiting conditions supported the coordinated activity of Rip1 and SigL and demonstrated that the loss of these proteins produces an exaggerated iron starvation response. These observations demonstrate that Rip1 coordinates several aspects of metal homeostasis and suggest that a Rip1- and SigL-dependent pathway is necessary to thrive in the iron-deficient environments encountered during infection. IMPORTANCE Metal homeostasis represents a critical point of interaction between the mammalian immune system and potential pathogens. While the host attempts to intoxicate microbes with high concentrations of copper or starve the invader of iron and zinc, successful pathogens have acquired mechanisms to overcome these defenses. Our work identifies a regulatory pathway consisting of the Rip1 intramembrane protease and the sigma factor, SigL, that is essential for the important human pathogen, Mycobacterium tuberculosis, to grow in low-iron or low-zinc conditions such as those encountered during infection. In conjunction with Rip1's known role in resisting copper toxicity, our work implicates this protein as a critical integration point that coordinates the multiple metal homeostatic systems required for this pathogen to survive in host tissue.
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Affiliation(s)
- Samantha J. Nelson
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - John T. Williams
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - John A. Buglino
- Immunology Program, Sloan Kettering Institute, New York City, New York, USA
| | - Subhalaxmi Nambi
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Lisa J. Lojek
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | | | - Thomas R. Ioerger
- Department of Computer Science and Engineering, Texas A&M University, College Station, Texas, USA
| | - Christopher M. Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
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25
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Italia A, Shaik MM, Peri F. Emerging Extracellular Molecular Targets for Innovative Pharmacological Approaches to Resistant Mtb Infection. Biomolecules 2023; 13:999. [PMID: 37371579 PMCID: PMC10296423 DOI: 10.3390/biom13060999] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Emerging pharmacological strategies that target major virulence factors of antibiotic-resistant Mycobacterium tuberculosis (Mtb) are presented and discussed. This review is divided into three parts corresponding to structures and functions important for Mtb pathogenicity: the cell wall, the lipoarabinomannan, and the secretory proteins. Within the cell wall, we further focus on three biopolymeric sub-components: mycolic acids, arabinogalactan, and peptidoglycan. We present a comprehensive overview of drugs and drug candidates that target cell walls, envelopes, and secretory systems. An understanding at a molecular level of Mtb pathogenesis is provided, and potential future directions in therapeutic strategies are suggested to access new drugs to combat the growing global threat of antibiotic-resistant Mtb infection.
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Affiliation(s)
| | | | - Francesco Peri
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milano, Italy; (A.I.); (M.M.S.)
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26
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Famelis N, Geibel S, van Tol D. Mycobacterial type VII secretion systems. Biol Chem 2023; 0:hsz-2022-0350. [PMID: 37276364 DOI: 10.1515/hsz-2022-0350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 05/22/2023] [Indexed: 06/07/2023]
Abstract
Mycobacteria, such as the pathogen M. tuberculosis, utilize up to five paralogous type VII secretion systems to transport proteins across their cell envelope. Since these proteins associate in pairs that depend on each other for transport to a different extent, the secretion pathway to the bacterial surface remained challenging to address. Structural characterization of the inner-membrane embedded secretion machineries along with recent advances on the substrates' co-dependencies for transport allow for the first time more detailed and testable models for secretion.
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Affiliation(s)
- Nikolaos Famelis
- Institute for Molecular Infection Biology, Julius Maximilian University of Würzburg, D-97080 Würzburg, Germany
| | - Sebastian Geibel
- Leiden Institute of Chemistry, Leiden University, NL-2333 CC Leiden, Netherlands
| | - Daan van Tol
- Leiden Institute of Chemistry, Leiden University, NL-2333 CC Leiden, Netherlands
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27
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Negrete-Paz AM, Vázquez-Marrufo G, Gutiérrez-Moraga A, Vázquez-Garcidueñas MS. Pangenome Reconstruction of Mycobacterium tuberculosis as a Guide to Reveal Genomic Features Associated with Strain Clinical Phenotype. Microorganisms 2023; 11:1495. [PMID: 37374997 DOI: 10.3390/microorganisms11061495] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Tuberculosis (TB) is one of the leading causes of human deaths worldwide caused by infectious diseases. TB infection by Mycobacterium tuberculosis can occur in the lungs, causing pulmonary tuberculosis (PTB), or in any other organ of the body, resulting in extrapulmonary tuberculosis (EPTB). There is no consensus on the genetic determinants of this pathogen that may contribute to EPTB. In this study, we constructed the M. tuberculosis pangenome and used it as a tool to seek genomic signatures associated with the clinical presentation of TB based on its accessory genome differences. The analysis carried out in the present study includes the raw reads of 490 M. tuberculosis genomes (PTB n = 245, EPTB n = 245) retrieved from public databases that were assembled, as well as ten genomes from Mexican strains (PTB n = 5, EPTB n = 5) that were sequenced and assembled. All genomes were annotated and then used to construct the pangenome with Roary and Panaroo. The pangenome obtained using Roary consisted of 2231 core genes and 3729 accessory genes. On the other hand, the pangenome resulting from Panaroo consisted of 2130 core genes and 5598 accessory genes. Associations between the distribution of accessory genes and the PTB/EPTB phenotypes were examined using the Scoary and Pyseer tools. Both tools found a significant association between the hspR, plcD, Rv2550c, pe_pgrs5, pe_pgrs25, and pe_pgrs57 genes and the PTB genotype. In contrast, the deletion of the aceA, esxR, plcA, and ppe50 genes was significantly associated with the EPTB phenotype. Rv1759c and Rv3740 were found to be associated with the PTB phenotype according to Scoary; however, these associations were not observed when using Pyseer. The robustness of the constructed pangenome and the gene-phenotype associations is supported by several factors, including the analysis of a large number of genomes, the inclusion of the same number of PTB/EPTB genomes, and the reproducibility of results thanks to the different bioinformatic tools used. Such characteristics surpass most of previous M. tuberculosis pangenomes. Thus, it can be inferred that the deletion of these genes can lead to changes in the processes involved in stress response and fatty acid metabolism, conferring phenotypic advantages associated with pulmonary or extrapulmonary presentation of TB. This study represents the first attempt to use the pangenome to seek gene-phenotype associations in M. tuberculosis.
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Affiliation(s)
- Andrea Monserrat Negrete-Paz
- División de Estudios de Posgrado, Facultad de Ciencias Médicas y Biológicas "Dr. Ignacio Chávez", Universidad Michoacana de San Nicolás de Hidalgo, Morelia 58020, Michoacán, Mexico
- Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Tarímbaro 58893, Michoacán, Mexico
| | - Gerardo Vázquez-Marrufo
- Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Tarímbaro 58893, Michoacán, Mexico
| | - Ana Gutiérrez-Moraga
- Instituto de Ciencias Biomédicas, Vicerrectoría de Investigación y Doctorados, Universidad Autónoma de Chile, Santiago 7500912, Chile
| | - Ma Soledad Vázquez-Garcidueñas
- División de Estudios de Posgrado, Facultad de Ciencias Médicas y Biológicas "Dr. Ignacio Chávez", Universidad Michoacana de San Nicolás de Hidalgo, Morelia 58020, Michoacán, Mexico
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28
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Parmar S, Tocheva EI. The cell envelope of Mycobacterium abscessus and its role in pathogenesis. PLoS Pathog 2023; 19:e1011318. [PMID: 37200238 DOI: 10.1371/journal.ppat.1011318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023] Open
Abstract
Mycobacterium abscessus is a nontuberculosis mycobacterium (NTM) that has shown an exponential rise in its ability to cause disease. Due to its ubiquitous presence in the environment, M. abscessus is widely implicated in secondary exacerbations of many nosocomial infections and genetic respiratory disorders, such as cystic fibrosis (CF). Contrary to other rapidly growing NTMs, the cell envelope of M. abscessus harbors several prominent features and undergoes modifications that are responsible for its pathogenesis. Compositional changes of the mycobacterial outer membrane (MOM) significantly decrease the presence of glycopeptidolipids (GPLs) and enable the transition from a colonizing, smooth morphotype into a virulent, rough morphotype. The GPLs are transported to the MOM by the Mycobacterial membrane proteins Large (MmpL), which further act as drug efflux pumps and confer antibiotic resistance. Lastly, M. abscessus possesses 2 type VII secretion systems (T7SS): ESX-3 and ESX-4, both of which have recently been implicated in host-pathogen interactions and virulence. This review summarizes the current knowledge of M. abscessus pathogenesis and highlights the clinically relevant association between the structure and functions of its cell envelope.
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Affiliation(s)
- Shweta Parmar
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Elitza I Tocheva
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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29
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Leddy O, White FM, Bryson BD. Immunopeptidomics reveals determinants of Mycobacterium tuberculosis antigen presentation on MHC class I. eLife 2023; 12:e84070. [PMID: 37073954 PMCID: PMC10159623 DOI: 10.7554/elife.84070] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 04/17/2023] [Indexed: 04/20/2023] Open
Abstract
CD8+ T cell recognition of Mycobacterium tuberculosis (Mtb)-specific peptides presented on major histocompatibility complex class I (MHC-I) contributes to immunity to tuberculosis (TB), but the principles that govern presentation of Mtb antigens on MHC-I are incompletely understood. In this study, mass spectrometry (MS) analysis of the MHC-I repertoire of Mtb-infected primary human macrophages reveals that substrates of Mtb's type VII secretion systems (T7SS) are overrepresented among Mtb-derived peptides presented on MHC-I. Quantitative, targeted MS shows that ESX-1 activity is required for presentation of Mtb peptides derived from both ESX-1 substrates and ESX-5 substrates on MHC-I, consistent with a model in which proteins secreted by multiple T7SSs access a cytosolic antigen processing pathway via ESX-1-mediated phagosome permeabilization. Chemical inhibition of proteasome activity, lysosomal acidification, or cysteine cathepsin activity did not block presentation of Mtb antigens on MHC-I, suggesting involvement of other proteolytic pathways or redundancy among multiple pathways. Our study identifies Mtb antigens presented on MHC-I that could serve as targets for TB vaccines, and reveals how the activity of multiple T7SSs interacts to contribute to presentation of Mtb antigens on MHC-I.
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Affiliation(s)
- Owen Leddy
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Ragon Institute of Massachusetts General Hospital, Harvard, and MITCambridgeUnited States
- Koch Institute for Integrative Cancer ResearchCambridgeUnited States
| | - Forest M White
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Koch Institute for Integrative Cancer ResearchCambridgeUnited States
- Center for Precision Cancer MedicineCambridgeUnited States
| | - Bryan D Bryson
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Ragon Institute of Massachusetts General Hospital, Harvard, and MITCambridgeUnited States
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Sun S, Wang M, Xiang J, Shao Y, Li L, Sedjoah RCAA, Wu G, Zhou J, Xin Z. BON domain-containing protein-mediated co-selection of antibiotic and heavy metal resistance in bacteria. Int J Biol Macromol 2023; 238:124062. [PMID: 36933600 DOI: 10.1016/j.ijbiomac.2023.124062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/12/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
The widespread antibiotic resistance of bacteria has become one of the most severe threats to public health. However, the mechanisms that allow microbial acquisition of resistance are still poorly understood. In the present study, a novel BON domain-containing protein was heterologously expressed in Escherichia coli. It functions as an efflux pump-like to confer resistance to various antibiotics, especially for ceftazidime, with a >32-fold increase in minimum inhibitory concentration (MIC). The fluorescence spectroscopy experiment indicated that BON protein could interact with several metal ions, such as copper and silver, which has been associated with the induced co-regulation of antibiotic and heavy metal resistance in bacteria. Furthermore, the BON protein was demonstrated to spontaneously self-assemble into a trimer and generate a central pore-like architecture for antibiotic transporting. A WXG motif as a molecular switch is essential for forming the transmembrane oligomeric pores and controls the interaction between BON protein and cell membrane. Based on these findings, a mechanism termed "one-in, one-out", was proposed for the first time. The present study provides new insights into the structure and function of BON protein and a previously unidentified antibiotic resistance mechanism, filling the knowledge gap in understanding BON protein-mediated intrinsic antibiotic resistance.
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Affiliation(s)
- Shengwei Sun
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Mengxi Wang
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Jiahui Xiang
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Yuting Shao
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Longxiang Li
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Rita-Cindy Aye-Ayire Sedjoah
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Guojun Wu
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Jingjie Zhou
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Zhihong Xin
- Key Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China.
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D'Souza C, Kishore U, Tsolaki AG. The PE-PPE Family of Mycobacterium tuberculosis: Proteins in Disguise. Immunobiology 2023; 228:152321. [PMID: 36805109 DOI: 10.1016/j.imbio.2022.152321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 12/31/2022]
Abstract
Mycobacterium tuberculosis has thrived in parallel with humans for millennia, and despite our efforts, M. tuberculosis continues to plague us, currently infecting a third of the world's population. The success of M. tuberculosis has recently been attributed, in part, to the PE-PPE family; a unique collection of 168 proteins fundamentally involved in the pathogenesis of M. tuberculosis. The PE-PPE family proteins have been at the forefront of intense research efforts since their discovery in 1998 and whilst our knowledge and understanding has significantly advanced over the last two decades, many important questions remain to be elucidated. This review consolidates and examines the vast body of existing literature regarding the PE-PPE family proteins, with respect to the latest developments in elucidating their evolution, structure, subcellular localisation, function, and immunogenicity. This review also highlights significant inconsistencies and contradictions within the field. Additionally, possible explanations for these knowledge gaps are explored. Lastly, this review poses many important questions, which need to be addressed to complete our understanding of the PE-PPE family, as well as highlighting the challenges associated with studying this enigmatic family of proteins. Further research into the PE-PPE family, together with technological advancements in genomics and proteomics, will undoubtedly improve our understanding of the pathogenesis of M. tuberculosis, as well as identify key targets/candidates for the development of novel drugs, diagnostics, and vaccines.
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Affiliation(s)
- Christopher D'Souza
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, United Kingdom
| | - Uday Kishore
- Department of Veterinary Medicine, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Anthony G Tsolaki
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, United Kingdom.
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Abstract
Mycobacterium abscessus is an emerging pathogen that critically depends on iron for growth and pathogenesis. The acquisition of iron in Mycobacterium tuberculosis is governed by siderophores called mycobactins, synthesized by the mbt gene cluster, but the role of this gene cluster in the adaption of M. abscessus to iron limitation is not characterized. We identified an M. abscessus Tn_mutant with interruption of the mbtE gene (MAB_2248c), a central component of mycobactin biosynthesis. We tested this isolate growth characteristic, dependency on supplements, and transcriptomic response, comparing it to the response of wild-type (WT) bacteria in iron-limiting conditions. We also compare the structure of the mbt gene cluster across several mycobacteria. The Tn_mbtE mutant had a substantial, but not absolute, growth defect, which was more substantial in iron-limited media. Supplementation with mycobactin-J, hemin, blood, and surprisingly, albumin, salvaged the poor growth. Similarly, secreted mature (carboxy)-mycobactins from WT bacteria rescued the Tn_mbtE mutant during iron deprivation. The transcriptomic response of the Tn_mbtE mutant involved the upregulation of genes known to be implicated in iron homeostasis and was comparable to that of WT bacteria grown in iron-limiting conditions. Interestingly, the response was not identical to the response of M. tuberculosis to iron limitation. The mbt gene cluster and mycobactins play important roles in the physiology of M. abscessus. (Carboxy)-mycobactin is secreted from WT bacteria and can serve as "public good." The role of several iron-homeostasis related genes (like ideR) may differ between M. abscessus and Mtb. IMPORTANCE Mycobacterium abscessus is an emerging human pathogen belonging to the nontuberculous mycobacteria (NTM) family, causing severe pulmonary disease in compromised individuals. How this bacterium acquires iron is poorly understood. Here, we provide the first characterization of the role(s) the mbtE gene required for the biosynthesis of siderophore mycobactin in M. abscessus. We show that the gene mbtE is required for growth during iron deprivation and can be compensated by several supplements, including, surprisingly, albumin. We also show the transcriptomic response of the mbtE-mutant is comparable to the response of the parental strain to iron starvation and seems different from the response of M. tuberculosis. These results indicate the importance of studying mycobactin in M. abscessus and NTM strains. Understanding this pathway is central to understanding the acquisition of iron within hosts and its role in pathogenesis, which in turn may facilitate the development of antimycobacterial therapeutics.
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The ESX-1 Substrate PPE68 Has a Key Function in ESX-1-Mediated Secretion in Mycobacterium marinum. mBio 2022; 13:e0281922. [PMID: 36409073 PMCID: PMC9765416 DOI: 10.1128/mbio.02819-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mycobacteria use specialized type VII secretion systems (T7SSs) to secrete proteins across their diderm cell envelope. One of the T7SS subtypes, named ESX-1, is a major virulence determinant in pathogenic species such as Mycobacterium tuberculosis and the fish pathogen Mycobacterium marinum. ESX-1 secretes a variety of substrates, called Esx, PE, PPE, and Esp proteins, at least some of which are folded heterodimers. Investigation into the functions of these substrates is problematic, because of the intricate network of codependent secretion between several ESX-1 substrates. Here, we describe the ESX-1 substrate PPE68 as essential for secretion of the highly immunogenic substrates EsxA and EspE via the ESX-1 system in M. marinum. While secreted PPE68 is processed on the cell surface, the majority of cell-associated PPE68 of M. marinum and M. tuberculosis is present in a cytosolic complex with its PE partner and the EspG1 chaperone. Interfering with the binding of EspG1 to PPE68 blocked its export and the secretion of EsxA and EspE. In contrast, esxA was not required for the secretion of PPE68, revealing a hierarchy in codependent secretion. Remarkably, the final 10 residues of PPE68, a negatively charged domain, seem essential for EspE secretion, but not for the secretion of EsxA and of PPE68 itself. This indicates that distinctive domains of PPE68 are involved in secretion of the different ESX-1 substrates. Based on these findings, we propose a mechanistic model for the central role of PPE68 in ESX-1-mediated secretion and substrate codependence. IMPORTANCE Pathogenic mycobacteria, such Mycobacterium tuberculosis and Mycobacterium marinum, use a type VII secretion system (T7SS) subtype, called ESX-1, to mediate intracellular survival via phagosomal rupture and subsequent translocation of the mycobacterium to the host cytosol. Identifying the ESX-1 substrate that is responsible for this process is problematic because of the intricate network of codependent secretion between ESX-1 substrates. Here, we show the central role of the ESX-1 substrate PPE68 for the secretion of ESX-1 substrates in Mycobacterium marinum. Unravelling the mechanism of codependent secretion will aid the functional understanding of T7SSs and will allow the analysis of the individual roles of ESX-1 substrates in the virulence caused by the significant human pathogen Mycobacterium tuberculosis.
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Boradia V, Frando A, Grundner C. The Mycobacterium tuberculosis PE15/PPE20 complex transports calcium across the outer membrane. PLoS Biol 2022; 20:e3001906. [PMID: 36441815 PMCID: PMC9731449 DOI: 10.1371/journal.pbio.3001906] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/08/2022] [Accepted: 11/04/2022] [Indexed: 11/29/2022] Open
Abstract
The mechanisms by which nutrients traverse the Mycobacterium tuberculosis (Mtb) outer membrane remain mostly unknown and, in the absence of classical porins, likely involve specialized transport systems. Calcium ions (Ca2+) are an important nutrient and serve as a second messenger in eukaryotes, but whether bacteria have similar Ca2+ signaling systems is not well understood. To understand the basis for Ca2+ transport and signaling in Mtb, we determined Mtb's transcriptional response to Ca2+. Overall, only few genes changed expression, suggesting a limited role of Ca2+ as a transcriptional regulator. However, 2 of the most strongly down-regulated genes were the pe15 and ppe20 genes that code for members of a large family of proteins that localize to the outer membrane and comprise many intrinsically disordered proteins. PE15 and PPE20 formed a complex and PPE20 directly bound Ca2+. Ca2+-associated phenotypes such as increased ATP consumption and biofilm formation were reversed in a pe15/ppe20 knockout (KO) strain, suggesting a direct role in Ca2+ homeostasis. To test whether the PE15/PPE20 complex has a role in Ca2+ transport across the outer membrane, we created a fluorescence resonance energy transfer (FRET)-based Ca2+ reporter strain. A pe15/ppe20 KO in the FRET background showed a specific and selective loss of Ca2+ influx that was dependent on the presence of an intact outer cell wall. These data show that PE15/PPE20 form a Ca2+-binding protein complex that selectively imports Ca2+, show a distinct transport function for an intrinsically disordered protein, and support the emerging idea of a general family-wide role of PE/PPE proteins as idiosyncratic transporters across the outer membrane.
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Affiliation(s)
- Vishant Boradia
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
| | - Andrew Frando
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
| | - Christoph Grundner
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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ppe51 Variants Enable Growth of Mycobacterium tuberculosis at Acidic pH by Selectively Promoting Glycerol Uptake. J Bacteriol 2022; 204:e0021222. [PMID: 36226966 PMCID: PMC9664963 DOI: 10.1128/jb.00212-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In defined media supplemented with single carbon sources, Mycobacterium tuberculosis (Mtb) exhibits carbon source specific growth restriction. When supplied with glycerol as the sole carbon source at pH 5.7, Mtb establishes a metabolically active state of nonreplicating persistence known as acid growth arrest. We hypothesized that acid growth arrest on glycerol is not a metabolic restriction, but rather an adaptive response. To test this hypothesis, we selected for and identified several Mtb mutants that could grow under these restrictive conditions. All mutations were mapped to the ppe51 gene and resulted in variants with 3 different amino acid substitutions- S211R, E215K, and A228D. Expression of the ppe51 variants in Mtb promoted growth at acidic pH showing that the mutant alleles are sufficient to cause the dominant gain-of-function, Enhanced Acid Growth (EAG) phenotype. Testing growth on other single carbon sources showed the PPE51 variants specifically enhanced growth on glycerol, suggesting PPE51 plays a role in glycerol uptake. Using radiolabeled glycerol, enhanced glycerol uptake was observed in Mtb expressing the PPE51 (S211R) variant, with glycerol overaccumulation in triacylglycerol. Notably, the EAG phenotype is deleterious for growth in macrophages, where the mutants have selectively faster replication and reduced survival in activated macrophages compared to resting macrophages. Recombinant PPE51 protein exhibited differential thermostability in the wild type (WT) or S211R variants in the presence of glycerol, supporting the model that EAG substitutions alter PPE51-glycerol interactions. Together, these findings support that PPE51 variants selectively promote glycerol uptake and that slowed growth at acidic pH is an important adaptive mechanism required for macrophage pathogenesis. IMPORTANCE It is puzzling why Mycobacterium tuberculosis (Mtb) cannot grow on glycerol at acidic pH, as it has a carbon source and oxygen, everything it needs to grow. In this study, we found that Mtb limits uptake of glycerol at acidic pH to restrict its growth and that mutations in ppe51 promote uptake of glycerol at acidic pH and enable growth. That is, Mtb can grow well at acidic pH on glycerol, but has adapted instead to stop growth. Notably, ppe51 variants exhibit enhanced replication and reduced survival in activated macrophages, supporting a role for pH-dependent slowed growth during macrophage pathogenesis.
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The Antibacterial Type VII Secretion System of Bacillus subtilis: Structure and Interactions of the Pseudokinase YukC/EssB. mBio 2022; 13:e0013422. [PMID: 36154281 PMCID: PMC9600267 DOI: 10.1128/mbio.00134-22] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Type VIIb secretion systems (T7SSb) were recently proposed to mediate different aspects of Firmicutes physiology, including bacterial pathogenicity and competition. However, their architecture and mechanism of action remain largely obscure. Here, we present a detailed analysis of the T7SSb-mediated bacterial competition in Bacillus subtilis, using the effector YxiD as a model for the LXG secreted toxins. By systematically investigating protein-protein interactions, we reveal that the membrane subunit YukC contacts all T7SSb components, including the WXG100 substrate YukE and the LXG effector YxiD. YukC’s crystal structure shows unique features, suggesting an intrinsic flexibility that is required for T7SSb antibacterial activity. Overall, our results shed light on the role and molecular organization of the T7SSb and demonstrate the potential of B. subtilis as a model system for extensive structure-function studies of these secretion machineries.
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Park HT, Lee SM, Ko S, Kim S, Park HE, Shin MK, Kim D, Yoo HS. Delineating transcriptional crosstalk between Mycobacterium avium subsp. paratuberculosis and human THP-1 cells at the early stage of infection via dual RNA-seq analysis. Vet Res 2022; 53:71. [PMID: 36100945 PMCID: PMC9469519 DOI: 10.1186/s13567-022-01089-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/13/2022] [Indexed: 12/02/2022] Open
Abstract
Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne’s disease, a chronic debilitating disease in ruminants. To control this disease, it is crucial to understand immune evasion and the mechanism of persistence by analyzing the early phase interplays of the intracellular pathogens and their hosts. In the present study, host–pathogen interactions at the transcriptomic level were investigated in an in vitro macrophage infection model. When differentiated human THP-1 cells were infected with MAP, the expression of various genes associated with stress responses and metabolism was altered in both host and MAP at 3 h post-infection. MAP upregulates stress-responsive global gene regulators, such as two-component systems and sigma factors, in response to oxidative and cell wall stress. Downstream genes involved in type VII secretion systems, cell wall synthesis (polyketide biosynthesis proteins), and iron uptake were changed in response to the intracellular environment of macrophages. On the host side, upregulation of inflammatory cytokine genes was observed along with pattern recognition receptor genes. Notably, alterations in gene sets involved in arginine metabolism were observed in both the host and MAP, along with significant downregulation of NOS2 expression. These observations suggest that the utilization of metabolites such as arginine by intracellular MAP might affect host NO production. Our dual RNA-seq data can provide novel insights by capturing the global transcriptome with higher resolution, especially in MAP, thus enabling a more systematic understanding of host–pathogen interactions.
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Affiliation(s)
- Hong-Tae Park
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul, 08826, Korea
| | - Sang-Mok Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Korea
| | - Seyoung Ko
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Korea
| | - Suji Kim
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul, 08826, Korea
| | - Hyun-Eui Park
- Department of Microbiology, College of Medicine, Research Institute of Life Science, Gyeongsang National University, Jinju, 52828, Korea
| | - Min-Kyoung Shin
- Department of Microbiology, College of Medicine, Research Institute of Life Science, Gyeongsang National University, Jinju, 52828, Korea
| | - Donghyuk Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Korea.
| | - Han Sang Yoo
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul, 08826, Korea.
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Bythrow GV, Farhat MF, Levendosky K, Mohandas P, Germain GA, Yoo B, Quadri LEN. Mycobacterium abscessus Mutants with a Compromised Functional Link between the Type VII ESX-3 System and an Iron Uptake Mechanism Reliant on an Unusual Mycobactin Siderophore. Pathogens 2022; 11:pathogens11090953. [PMID: 36145386 PMCID: PMC9505556 DOI: 10.3390/pathogens11090953] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/12/2022] [Accepted: 08/18/2022] [Indexed: 11/28/2022] Open
Abstract
The opportunistic pathogen Mycobacterium abscessus subsp. abscessus (Mab) has become an emerging public health threat due to the increasing number of Mab-associated chronic pulmonary disease cases. Treatment requires multiple drug courses and is often combined with surgical resection. Cure rates are only ~50% due to treatment failure and comorbidities. Deeper understanding of the biology of Mab is required to illuminate potential avenues for the development of better therapeutics against Mab infections. The ESX-3 type VII protein secretion system of Mab has an important role in host inflammatory and pathological responses during infection. In this work, we demonstrate a functional link between ESX-3 and an iron uptake system based on an unusual mycobactin-type siderophore (designated MBT Ab) and exploit this link to implement a large screen for transposon mutants with an impaired ESX-3. Most mutants we identified carry insertions in genes encoding predicted ESX-3 secretion machinery components or potential ESX-3 substrates. The mutants overproduce MBT Ab, a trait consistent with an iron uptake defect. Our characterization of MBT Ab revealed structural features reminiscent of nocardial mycobactin-like compounds with cytotoxicity. This finding raises the possibility that MBT Ab may play roles in pathogenesis unlinked to iron homeostasis. The mutants generated herein will facilitate research to better understand the role of ESX-3 and its interplay with the siderophore system.
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Affiliation(s)
- Glennon V. Bythrow
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Manal F. Farhat
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Keith Levendosky
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Poornima Mohandas
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Gabrielle A. Germain
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Barney Yoo
- Department of Chemistry, Hunter College, City University of New York, 695 Park Avenue, New York, NY 10065, USA
| | - Luis E. N. Quadri
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- Biochemistry Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- Correspondence:
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Lagune M, Le Moigne V, Johansen MD, Vásquez Sotomayor F, Daher W, Petit C, Cosentino G, Paulowski L, Gutsmann T, Wilmanns M, Maurer FP, Herrmann JL, Girard-Misguich F, Kremer L. The ESX-4 substrates, EsxU and EsxT, modulate Mycobacterium abscessus fitness. PLoS Pathog 2022; 18:e1010771. [PMID: 35960766 PMCID: PMC9401124 DOI: 10.1371/journal.ppat.1010771] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 08/24/2022] [Accepted: 07/27/2022] [Indexed: 11/19/2022] Open
Abstract
ESX type VII secretion systems are complex secretion machineries spanning across the mycobacterial membrane and play an important role in pathogenicity, nutrient uptake and conjugation. We previously reported the role of ESX-4 in modulating Mycobacterium abscessus intracellular survival. The loss of EccB4 was associated with limited secretion of two effector proteins belonging to the WXG-100 family, EsxU and EsxT, and encoded by the esx-4 locus. This prompted us to investigate the function of M. abscessus EsxU and EsxT in vitro and in vivo. Herein, we show that EsxU and EsxT are substrates of ESX-4 and form a stable 1:1 heterodimer that permeabilizes artificial membranes. While expression of esxU and esxT was up-regulated in M. abscessus-infected macrophages, their absence in an esxUT deletion mutant prevented phagosomal membrane disruption while maintaining M. abscessus in an unacidified phagosome. Unexpectedly, the esxUT deletion was associated with a hyper-virulent phenotype, characterised by increased bacterial loads and mortality in mouse and zebrafish infection models. Collectively, these results demonstrate that the presence of EsxU and EsxT dampens survival and persistence of M. abscessus during infection.
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Affiliation(s)
- Marion Lagune
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - Vincent Le Moigne
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - Matt D. Johansen
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
| | - Flor Vásquez Sotomayor
- National and WHO Supranational Reference Center for Mycobacteria, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Wassim Daher
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
- INSERM, IRIM, Montpellier, France
| | - Cécile Petit
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Gina Cosentino
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - Laura Paulowski
- National and WHO Supranational Reference Center for Mycobacteria, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Thomas Gutsmann
- Research Center Borstel, Leibniz Lung Center, Division of Biophysics, Borstel, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
- * E-mail: (MW); (FPM); (J-LH); (FG-M); (LK)
| | - Florian P. Maurer
- National and WHO Supranational Reference Center for Mycobacteria, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
- Institute of Medical Microbiology, Virology and Hospital Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail: (MW); (FPM); (J-LH); (FG-M); (LK)
| | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
- APHP, GHU Paris-Saclay, Hôpital Raymond Poincaré, Service de Microbiologie, Garches, France
- * E-mail: (MW); (FPM); (J-LH); (FG-M); (LK)
| | - Fabienne Girard-Misguich
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
- * E-mail: (MW); (FPM); (J-LH); (FG-M); (LK)
| | - Laurent Kremer
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
- INSERM, IRIM, Montpellier, France
- * E-mail: (MW); (FPM); (J-LH); (FG-M); (LK)
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Bar-Oz M, Meir M, Barkan D. Virulence-Associated Secretion in Mycobacterium abscessus. Front Immunol 2022; 13:938895. [PMID: 35880173 PMCID: PMC9308005 DOI: 10.3389/fimmu.2022.938895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Non-tuberculous mycobacteria (NTM) are a heterogeneous group of originally environmental organi3sms, increasingly recognized as pathogens with rising prevalence worldwide. Knowledge of NTM’s mechanisms of virulence is lacking, as molecular research of these bacteria is challenging, sometimes more than that of M. tuberculosis (Mtb), and far less resources are allocated to their investigation. While some of the virulence mechanisms are common to several mycobacteria including Mtb, others NTM species-specific. Among NTMs, Mycobacterium abscessus (Mabs) causes some of the most severe and difficult to treat infections, especially chronic pulmonary infections. Mabs survives and proliferates intracellularly by circumventing host defenses, using multiple mechanisms, many of which remain poorly characterized. Some of these immune-evasion mechanisms are also found in Mtb, including phagosome pore formation, inhibition of phagosome maturation, cytokine response interference and apoptosis delay. While much is known of the role of Mtb-secreted effector molecules in mediating the manipulation of the host response, far less is known of the secreted effector molecules in Mabs. In this review, we briefly summarize the knowledge of secreted effectors in Mtb (such as ESX secretion, SecA2, TAT and others), and draw the parallel pathways in Mabs. We also describe pathways that are unique to Mabs, differentiating it from Mtb. This review will assist researchers interested in virulence-associated secretion in Mabs by providing the knowledge base and framework for their studies.
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Affiliation(s)
- Michal Bar-Oz
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Michal Meir
- The Ruth Rappaport Children’s Hospital, Rambam Medical Center, Haifa, Israel
| | - Daniel Barkan
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
- *Correspondence: Daniel Barkan,
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41
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Secretory proteins of
Mycobacterium tuberculosis
and their roles in modulation of host immune responses: focus on therapeutic targets. FEBS J 2022; 289:4146-4171. [DOI: 10.1111/febs.16369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 01/04/2022] [Accepted: 01/21/2022] [Indexed: 12/01/2022]
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Gauthier DT, Doss JH, LaGatta M, Gupta T, Karls RK, Quinn FD. Genomic Degeneration and Reduction in the Fish Pathogen Mycobacterium shottsii. Microbiol Spectr 2022; 10:e0115821. [PMID: 35579461 PMCID: PMC9241763 DOI: 10.1128/spectrum.01158-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 04/26/2022] [Indexed: 01/17/2023] Open
Abstract
Mycobacterium shottsii is a dysgonic, nonpigmented mycobacterium originally isolated from diseased striped bass (Morone saxatilis) in the Chesapeake Bay, USA. Genomic analysis reveals that M. shottsii is a Mycobacterium ulcerans/Mycobacterium marinum clade (MuMC) member, but unlike the superficially similar M. pseudoshottsii, also isolated from striped bass, it is not an M. ulcerans ecovar, instead belonging to a transitional group of strains basal to proposed "Aronson" and "M" lineages. Although phylogenetically distinct from the human pathogen M. ulcerans, the M. shottsii genome shows parallel but nonhomologous genomic degeneration, including massive accumulation of pseudogenes accompanied by proliferation of unique insertion sequences (ISMysh01, ISMysh03), large-scale deletions, and genomic reorganization relative to typical M. marinum strains. Coupled with its observed ecological characteristics and loss of chromogenicity, the genomic structure of M. shottsii is suggestive of evolution toward a state of obligate pathogenicity, as observed for other Mycobacterium spp., including M. ulcerans, M. tuberculosis, and M. leprae. IMPORTANCE Morone saxatilis (striped bass) is an ecologically and economically important finfish species on the United States east coast. Mycobacterium shottsii and Mycobacterium pseudoshottsii were originally described in the early 2000s as novel species from outbreaks of visceral and dermal mycobacteriosis in this species. Biochemical and genetic characterization place these species within the Mycobacterium ulcerans/M. marinum clade (MuMC), and M. pseudoshottsii has been proposed as an ecovar of M. ulcerans. Here, we describe the complete genome of M. shottsii, demonstrating that it is clearly not an M. ulcerans ecovar; however, it has undergone parallel genomic modification suggestive of a transition to obligate pathogenicity. As in M. ulcerans, the M. shottsii genome demonstrates widespread pseudogene formation driven by proliferation of insertion sequences, as well as genomic reorganization. This work clarifies the phylogenetic position of M. shottsii relative to other MuMC members and provides insight into processes shaping its genomic structure.
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Affiliation(s)
- D. T. Gauthier
- Department of Biological Sciences, Old Dominion University, Norfolk, Virginia, USA
| | - J. H. Doss
- Department of Biological Sciences, Old Dominion University, Norfolk, Virginia, USA
| | - M. LaGatta
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
- Pathens Incorporated, Athens, Georgia, USA
| | - T. Gupta
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
| | - R. K. Karls
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
- Pathens Incorporated, Athens, Georgia, USA
| | - F. D. Quinn
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
- Pathens Incorporated, Athens, Georgia, USA
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43
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Pepperell CS. Evolution of Tuberculosis Pathogenesis. Annu Rev Microbiol 2022; 76:661-680. [PMID: 35709500 DOI: 10.1146/annurev-micro-121321-093031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mycobacterium tuberculosis is a globally distributed, lethal pathogen of humans. The virulence armamentarium of M. tuberculosis appears to have been developed on a scaffold of antiphagocytic defenses found among diverse, mostly free-living species of Mycobacterium. Pathoadaptation was further aided by the modularity, flexibility, and interactivity characterizing mycobacterial effectors and their regulators. During emergence of M. tuberculosis, novel genetic material was acquired, created, and integrated with existing tools. The major mutational mechanisms underlying these adaptations are discussed in this review, with examples. During its evolution, M. tuberculosis lost the ability and/or opportunity to engage in lateral gene transfer, but despite this it has retained the adaptability that characterizes mycobacteria. M. tuberculosis exemplifies the evolutionary genomic mechanisms underlying adoption of the pathogenic niche, and studies of its evolution have uncovered a rich array of discoveries about how new pathogens are made. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Caitlin S Pepperell
- Division of Infectious Diseases, Department of Medicine, and Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA;
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44
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Horetski M, Gorlova A, Płocińska R, Brzostek A, Faletrov Y, Dziadek J, Shkumatov V. Synthesis, Optical Properties, Preliminary Antimycobacterial Evaluation and Docking Studies of Trifluoroacetylated 3‐Pyrrolyl Boron‐Dipyrromethene. ChemistrySelect 2022. [DOI: 10.1002/slct.202200506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Matvey Horetski
- Department of Macromolecular Compounds Belarusian State University 14 Leningradskaya Street. Minsk 220030 Belarus
| | - Anna Gorlova
- Department of Natural Sciences Novosibirsk State University 1 Pirogova Street. Novosibirsk 630090 Russia
| | - Renata Płocińska
- The Institute of Medical Biology Polish Academy of Sciences 106 Lodowa Street. Lodz 93-232 Poland
| | - Anna Brzostek
- The Institute of Medical Biology Polish Academy of Sciences 106 Lodowa Street. Lodz 93-232 Poland
| | - Yaroslav Faletrov
- Department of Macromolecular Compounds Belarusian State University 14 Leningradskaya Street. Minsk 220030 Belarus
| | - Jarosław Dziadek
- The Institute of Medical Biology Polish Academy of Sciences 106 Lodowa Street. Lodz 93-232 Poland
| | - Vladimir Shkumatov
- Department of Macromolecular Compounds Belarusian State University 14 Leningradskaya Street. Minsk 220030 Belarus
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45
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Kriel NL, Newton-Foot M, Bennion OT, Aldridge BB, Mehaffy C, Belisle JT, Walzl G, Warren RM, Sampson SL, Gey van Pittius NC. Localization of EccA 3 at the growing pole in Mycobacterium smegmatis. BMC Microbiol 2022; 22:140. [PMID: 35590245 PMCID: PMC9118679 DOI: 10.1186/s12866-022-02554-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/09/2022] [Indexed: 11/30/2022] Open
Abstract
Background Bacteria require specialized secretion systems for the export of molecules into the extracellular space to modify their environment and scavenge for nutrients. The ESX-3 secretion system is required by mycobacteria for iron homeostasis. The ESX-3 operon encodes for one cytoplasmic component (EccA3) and five membrane components (EccB3 – EccE3 and MycP3). In this study we sought to identify the sub-cellular location of EccA3 of the ESX-3 secretion system in mycobacteria. Results Fluorescently tagged EccA3 localized to a single pole in the majority of Mycobacterium smegmatis cells and time-lapse fluorescent microscopy identified this pole as the growing pole. Deletion of ESX-3 did not prevent polar localization of fluorescently tagged EccA3, suggesting that EccA3 unipolar localization is independent of other ESX-3 components. Affinity purification - mass spectrometry was used to identify EccA3 associated proteins which may contribute to the localization of EccA3 at the growing pole. EccA3 co-purified with fatty acid metabolism proteins (FAS, FadA3, KasA and KasB), mycolic acid synthesis proteins (UmaA, CmaA1), cell division proteins (FtsE and FtsZ), and cell shape and cell cycle proteins (MurS, CwsA and Wag31). Secretion system related proteins Ffh, SecA1, EccA1, and EspI were also identified. Conclusions Time-lapse microscopy demonstrated that EccA3 is located at the growing pole in M. smegmatis. The co-purification of EccA3 with proteins known to be required for polar growth, mycolic acid synthesis, the Sec secretion system (SecA1), and the signal recognition particle pathway (Ffh) also suggests that EccA3 is located at the site of active cell growth. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-022-02554-6.
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Affiliation(s)
- Nastassja L Kriel
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
| | - Mae Newton-Foot
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Owen T Bennion
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Bree B Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Carolina Mehaffy
- Mycobacteria Research Laboratories, Department of Microbiology Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523, USA
| | - John T Belisle
- Mycobacteria Research Laboratories, Department of Microbiology Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Gerhard Walzl
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Robin M Warren
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Samantha L Sampson
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Nico C Gey van Pittius
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
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46
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Rodriguez GM, Sharma N, Biswas A, Sharma N. The Iron Response of Mycobacterium tuberculosis and Its Implications for Tuberculosis Pathogenesis and Novel Therapeutics. Front Cell Infect Microbiol 2022; 12:876667. [PMID: 35646739 PMCID: PMC9132128 DOI: 10.3389/fcimb.2022.876667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 03/25/2022] [Indexed: 12/16/2022] Open
Abstract
Most pathogenic bacteria require iron for growth. However, this metal is not freely available in the mammalian host. Due to its poor solubility and propensity to catalyze the generation of reactive oxygen species, host iron is kept in solution bound to specialized iron binding proteins. Access to iron is an important factor in the outcome of bacterial infections; iron limitation frequently induces virulence and drives pathogenic interactions with host cells. Here, we review the response of Mycobacterium tuberculosis to changes in iron availability, the relevance of this response to TB pathogenesis, and its potential for the design of new therapeutic interventions.
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47
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Zhang L, Kent JE, Whitaker M, Young DC, Herrmann D, Aleshin AE, Ko YH, Cingolani G, Saad JS, Moody DB, Marassi FM, Ehrt S, Niederweis M. A periplasmic cinched protein is required for siderophore secretion and virulence of Mycobacterium tuberculosis. Nat Commun 2022; 13:2255. [PMID: 35474308 PMCID: PMC9042941 DOI: 10.1038/s41467-022-29873-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 03/31/2022] [Indexed: 11/16/2022] Open
Abstract
Iron is essential for growth of Mycobacterium tuberculosis, the causative agent of tuberculosis. To acquire iron from the host, M. tuberculosis uses the siderophores called mycobactins and carboxymycobactins. Here, we show that the rv0455c gene is essential for M. tuberculosis to grow in low-iron medium and that secretion of both mycobactins and carboxymycobactins is drastically reduced in the rv0455c deletion mutant. Both water-soluble and membrane-anchored Rv0455c are functional in siderophore secretion, supporting an intracellular role. Lack of Rv0455c results in siderophore toxicity, a phenotype observed for other siderophore secretion mutants, and severely impairs replication of M. tuberculosis in mice, demonstrating the importance of Rv0455c and siderophore secretion during disease. The crystal structure of a Rv0455c homolog reveals a novel protein fold consisting of a helical bundle with a 'cinch' formed by an essential intramolecular disulfide bond. These findings advance our understanding of the distinct M. tuberculosis siderophore secretion system.
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Affiliation(s)
- Lei Zhang
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - James E Kent
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Meredith Whitaker
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - David C Young
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Dominik Herrmann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Alexander E Aleshin
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Ying-Hui Ko
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - D Branch Moody
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Francesca M Marassi
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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48
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Chung ES, Johnson WC, Aldridge BB. Types and functions of heterogeneity in mycobacteria. Nat Rev Microbiol 2022; 20:529-541. [PMID: 35365812 DOI: 10.1038/s41579-022-00721-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2022] [Indexed: 12/24/2022]
Abstract
The remarkable ability of Mycobacterium tuberculosis to survive attacks from the host immune response and drug treatment is due to the resilience of a few bacilli rather than a result of survival of the entire population. Maintenance of mycobacterial subpopulations with distinct phenotypic characteristics is key for survival in the face of dynamic and variable stressors encountered during infection. Mycobacterial populations develop a wide range of phenotypes through an innate asymmetric growth pattern and adaptation to fluctuating microenvironments during infection that point to heterogeneity being a vital survival strategy. In this Review, we describe different types of mycobacterial heterogeneity and discuss how heterogeneity is generated and regulated in response to environmental cues. We discuss how this heterogeneity may have a key role in recording memory of their environment at both the single-cell level and the population level to give mycobacterial populations plasticity to withstand complex stressors.
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Affiliation(s)
- Eun Seon Chung
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - William C Johnson
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.,Tufts University School of Graduate Biomedical Sciences, Boston, MA, USA
| | - Bree B Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA. .,Tufts University School of Graduate Biomedical Sciences, Boston, MA, USA. .,Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Tufts University, Boston, MA, USA. .,Department of Biomedical Engineering, Tufts University School of Engineering, Medford, MA, USA.
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49
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Ferrell KC, Johansen MD, Triccas JA, Counoupas C. Virulence Mechanisms of Mycobacterium abscessus: Current Knowledge and Implications for Vaccine Design. Front Microbiol 2022; 13:842017. [PMID: 35308378 PMCID: PMC8928063 DOI: 10.3389/fmicb.2022.842017] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/08/2022] [Indexed: 12/22/2022] Open
Abstract
Mycobacterium abscessus is a member of the non-tuberculous mycobacteria (NTM) group, responsible for chronic infections in individuals with cystic fibrosis (CF) or those otherwise immunocompromised. While viewed traditionally as an opportunistic pathogen, increasing research into M. abscessus in recent years has highlighted its continued evolution into a true pathogen. This is demonstrated through an extensive collection of virulence factors (VFs) possessed by this organism which facilitate survival within the host, particularly in the harsh environment of the CF lung. These include VFs resembling those of other Mycobacteria, and non-mycobacterial VFs, both of which make a notable contribution in shaping M. abscessus interaction with the host. Mycobacterium abscessus continued acquisition of VFs is cause for concern and highlights the need for novel vaccination strategies to combat this pathogen. An effective M. abscessus vaccine must be suitably designed for target populations (i.e., individuals with CF) and incorporate current knowledge on immune correlates of protection against M. abscessus infection. Vaccination strategies must also build upon lessons learned from ongoing efforts to develop novel vaccines for other pathogens, particularly Mycobacterium tuberculosis (M. tb); decades of research into M. tb has provided insight into unconventional and innovative vaccine approaches that may be applied to M. abscessus. Continued research into M. abscessus pathogenesis will be critical for the future development of safe and effective vaccines and therapeutics to reduce global incidence of this emerging pathogen.
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Affiliation(s)
- Kia C. Ferrell
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
- Tuberculosis Research Program, Centenary Institute, Sydney, NSW, Australia
- *Correspondence: Kia C. Ferrell,
| | - Matt D. Johansen
- Centre for Inflammation, Centenary Institute, University of Technology, Sydney, NSW, Australia
- Faculty of Science, School of Life Sciences, University of Technology, Sydney, NSW, Australia
| | - James A. Triccas
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
- Sydney Institute for Infectious Diseases and the Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Claudio Counoupas
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
- Tuberculosis Research Program, Centenary Institute, Sydney, NSW, Australia
- Sydney Institute for Infectious Diseases and the Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
- Claudio Counoupas,
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50
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Multiple genetic paths including massive gene amplification allow Mycobacterium tuberculosis to overcome loss of ESX-3 secretion system substrates. Proc Natl Acad Sci U S A 2022; 119:2112608119. [PMID: 35193958 PMCID: PMC8872769 DOI: 10.1073/pnas.2112608119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2021] [Indexed: 01/18/2023] Open
Abstract
The Mycobacterium tuberculosis (Mtb) ESX-3 type VII secretion system plays a critical role in iron acquisition. Infection of mice with highly attenuated Mtb deletion mutants lacking esxG or esxH, genes encoding key ESX-3 substrates, unexpectedly yielded suppressor mutants with restored capacity to grow in vivo and in vitro in the absence of iron supplementation. Whole-genome sequencing identified two mechanisms of suppression, the disruption of a transcriptional repressor that regulates expression of an ESX-3 paralogous region encoding EsxR and EsxS, and a massive 38- to 60-fold gene amplification of this same region. These data are significant because they reveal a previously unrecognized iron acquisition regulon and inform mechanisms of Mtb chromosome evolution. Mycobacterium tuberculosis (Mtb) possesses five type VII secretion systems (T7SS), virulence determinants that include the secretion apparatus and associated secretion substrates. Mtb strains deleted for the genes encoding substrates of the ESX-3 T7SS, esxG or esxH, require iron supplementation for in vitro growth and are highly attenuated in vivo. In a subset of infected mice, suppressor mutants of esxG or esxH deletions were isolated, which enabled growth to high titers or restored virulence. Suppression was conferred by mechanisms that cause overexpression of an ESX-3 paralogous region that lacks genes for the secretion apparatus but encodes EsxR and EsxS, apparent ESX-3 orphan substrates that functionally compensate for the lack of EsxG or EsxH. The mechanisms include the disruption of a transcriptional repressor and a massive 38- to 60-fold gene amplification. These data identify an iron acquisition regulon, provide insight into T7SS, and reveal a mechanism of Mtb chromosome evolution involving “accordion-type” amplification.
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