1
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Jowsey WJ, Cook GM, McNeil MB. Antibiotic resistance in Mycobacterium tuberculosis alters tolerance to cell wall-targeting inhibitors. JAC Antimicrob Resist 2024; 6:dlae086. [PMID: 38836195 PMCID: PMC11148391 DOI: 10.1093/jacamr/dlae086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 05/11/2024] [Indexed: 06/06/2024] Open
Abstract
Background A limited ability to eliminate drug-resistant strains of Mycobacterium tuberculosis is a major contributor to the morbidity of TB. Complicating this problem, little is known about how drug resistance-conferring mutations alter the ability of M. tuberculosis to tolerate antibiotic killing. Here, we investigated if drug-resistant strains of M. tuberculosis have an altered ability to tolerate killing by cell wall-targeting inhibitors. Methods Bacterial killing and MIC assays were used to test for antibiotic tolerance and synergy against a panel of drug-resistant M. tuberculosis strains. Results Our results demonstrate that vancomycin and thioacetazone exhibit increased killing of diverse drug-resistant strains. Mutations in mmaA4 and mmpL3 increased vancomycin killing, which was consistent with vancomycin synergizing with thioacetazone and MmpL3-targeting inhibitors. In contrast, mutations in the mce1 operon conferred tolerance to vancomycin. Conclusions Overall, this work demonstrates how drug-resistant strains experience perturbations in cell-wall production that alters their tolerance to killing by cell wall-targeting inhibitors.
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Affiliation(s)
- William J Jowsey
- 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
| | - Matthew B McNeil
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
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2
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Alexander LT, Durairaj J, Kryshtafovych A, Abriata LA, Bayo Y, Bhabha G, Breyton C, Caulton SG, Chen J, Degroux S, Ekiert DC, Erlandsen BS, Freddolino PL, Gilzer D, Greening C, Grimes JM, Grinter R, Gurusaran M, Hartmann MD, Hitchman CJ, Keown JR, Kropp A, Kursula P, Lovering AL, Lemaitre B, Lia A, Liu S, Logotheti M, Lu S, Markússon S, Miller MD, Minasov G, Niemann HH, Opazo F, Phillips GN, Davies OR, Rommelaere S, Rosas‐Lemus M, Roversi P, Satchell K, Smith N, Wilson MA, Wu K, Xia X, Xiao H, Zhang W, Zhou ZH, Fidelis K, Topf M, Moult J, Schwede T. Protein target highlights in CASP15: Analysis of models by structure providers. Proteins 2023; 91:1571-1599. [PMID: 37493353 PMCID: PMC10792529 DOI: 10.1002/prot.26545] [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: 06/12/2023] [Accepted: 06/15/2023] [Indexed: 07/27/2023]
Abstract
We present an in-depth analysis of selected CASP15 targets, focusing on their biological and functional significance. The authors of the structures identify and discuss key protein features and evaluate how effectively these aspects were captured in the submitted predictions. While the overall ability to predict three-dimensional protein structures continues to impress, reproducing uncommon features not previously observed in experimental structures is still a challenge. Furthermore, instances with conformational flexibility and large multimeric complexes highlight the need for novel scoring strategies to better emphasize biologically relevant structural regions. Looking ahead, closer integration of computational and experimental techniques will play a key role in determining the next challenges to be unraveled in the field of structural molecular biology.
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Affiliation(s)
- Leila T. Alexander
- BiozentrumUniversity of BaselBaselSwitzerland
- Computational Structural BiologySIB Swiss Institute of BioinformaticsBaselSwitzerland
| | - Janani Durairaj
- BiozentrumUniversity of BaselBaselSwitzerland
- Computational Structural BiologySIB Swiss Institute of BioinformaticsBaselSwitzerland
| | | | - Luciano A. Abriata
- School of Life SciencesÉcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Yusupha Bayo
- Department of BiosciencesUniversity of MilanoMilanItaly
- IBBA‐CNR Unit of MilanoInstitute of Agricultural Biology and BiotechnologyMilanItaly
| | - Gira Bhabha
- Department of Cell BiologyNew York University School of MedicineNew YorkNew YorkUSA
| | | | | | - James Chen
- Department of Cell BiologyNew York University School of MedicineNew YorkNew YorkUSA
| | | | - Damian C. Ekiert
- Department of Cell BiologyNew York University School of MedicineNew YorkNew YorkUSA
- Department of MicrobiologyNew York University School of MedicineNew YorkNew YorkUSA
| | - Benedikte S. Erlandsen
- Wellcome Centre for Cell BiologyInstitute of Cell Biology, University of EdinburghEdinburghUK
| | - Peter L. Freddolino
- Department of Biological Chemistry, Computational Medicine and BioinformaticsUniversity of MichiganAnn ArborMichiganUSA
| | - Dominic Gilzer
- Department of ChemistryBielefeld UniversityBielefeldGermany
| | - Chris Greening
- Department of Microbiology, Biomedicine Discovery InstituteMonash UniversityClaytonVictoriaAustralia
- Securing Antarctica's Environmental FutureMonash UniversityClaytonVictoriaAustralia
- Centre to Impact AMRMonash UniversityClaytonVictoriaAustralia
- ARC Research Hub for Carbon Utilisation and RecyclingMonash UniversityClaytonVictoriaAustralia
| | - Jonathan M. Grimes
- Division of Structural Biology, Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Rhys Grinter
- Department of Microbiology, Biomedicine Discovery InstituteMonash UniversityClaytonVictoriaAustralia
- Centre for Electron Microscopy of Membrane ProteinsMonash Institute of Pharmaceutical SciencesParkvilleVictoriaAustralia
| | - Manickam Gurusaran
- Wellcome Centre for Cell BiologyInstitute of Cell Biology, University of EdinburghEdinburghUK
| | - Marcus D. Hartmann
- Max Planck Institute for BiologyTübingenGermany
- Interfaculty Institute of Biochemistry, University of TübingenTübingenGermany
| | - Charlie J. Hitchman
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLeicesterUK
| | - Jeremy R. Keown
- Division of Structural Biology, Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Ashleigh Kropp
- Department of Microbiology, Biomedicine Discovery InstituteMonash UniversityClaytonVictoriaAustralia
| | - Petri Kursula
- Department of BiomedicineUniversity of BergenBergenNorway
- Faculty of Biochemistry and Molecular Medicine & Biocenter OuluUniversity of OuluOuluFinland
| | | | - Bruno Lemaitre
- School of Life SciencesÉcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Andrea Lia
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLeicesterUK
- ISPA‐CNR Unit of LecceInstitute of Sciences of Food ProductionLecceItaly
| | - Shiheng Liu
- Department of Microbiology, Immunology, and Molecular GeneticsUniversity of CaliforniaLos AngelesCaliforniaUSA
- California NanoSystems InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Maria Logotheti
- Max Planck Institute for BiologyTübingenGermany
- Interfaculty Institute of Biochemistry, University of TübingenTübingenGermany
- Present address:
Institute of BiochemistryUniversity of GreifswaldGreifswaldGermany
| | - Shuze Lu
- Lanzhou University School of Life SciencesLanzhouChina
| | | | | | - George Minasov
- Department of Microbiology‐ImmunologyNorthwestern Feinberg School of MedicineChicagoIllinoisUSA
| | | | - Felipe Opazo
- NanoTag Biotechnologies GmbHGöttingenGermany
- Institute of Neuro‐ and Sensory PhysiologyUniversity of Göttingen Medical CenterGöttingenGermany
- Center for Biostructural Imaging of Neurodegeneration (BIN)University of Göttingen Medical CenterGöttingenGermany
| | - George N. Phillips
- Department of BiosciencesRice UniversityHoustonTexasUSA
- Department of ChemistryRice UniversityHoustonTexasUSA
| | - Owen R. Davies
- Wellcome Centre for Cell BiologyInstitute of Cell Biology, University of EdinburghEdinburghUK
| | - Samuel Rommelaere
- School of Life SciencesÉcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Monica Rosas‐Lemus
- Department of Microbiology‐ImmunologyNorthwestern Feinberg School of MedicineChicagoIllinoisUSA
- Present address:
Department of Molecular Genetics and MicrobiologyUniversity of New MexicoAlbuquerqueNew MexicoUSA
| | - Pietro Roversi
- IBBA‐CNR Unit of MilanoInstitute of Agricultural Biology and BiotechnologyMilanItaly
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLeicesterUK
| | - Karla Satchell
- Department of Microbiology‐ImmunologyNorthwestern Feinberg School of MedicineChicagoIllinoisUSA
| | - Nathan Smith
- Department of Biochemistry and the Redox Biology CenterUniversity of NebraskaLincolnNebraskaUSA
| | - Mark A. Wilson
- Department of Biochemistry and the Redox Biology CenterUniversity of NebraskaLincolnNebraskaUSA
| | - Kuan‐Lin Wu
- Department of ChemistryRice UniversityHoustonTexasUSA
| | - Xian Xia
- Department of Microbiology, Immunology, and Molecular GeneticsUniversity of CaliforniaLos AngelesCaliforniaUSA
- California NanoSystems InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Han Xiao
- Department of BiosciencesRice UniversityHoustonTexasUSA
- Department of ChemistryRice UniversityHoustonTexasUSA
- Department of BioengineeringRice UniversityHoustonTexasUSA
| | - Wenhua Zhang
- Lanzhou University School of Life SciencesLanzhouChina
| | - Z. Hong Zhou
- Department of Microbiology, Immunology, and Molecular GeneticsUniversity of CaliforniaLos AngelesCaliforniaUSA
- California NanoSystems InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA
| | | | - Maya Topf
- University Medical Center Hamburg‐Eppendorf (UKE)HamburgGermany
- Centre for Structural Systems BiologyLeibniz‐Institut für Virologie (LIV)HamburgGermany
| | - John Moult
- Department of Cell Biology and Molecular Genetics, Institute for Bioscience and Biotechnology ResearchUniversity of MarylandRockvilleMarylandUSA
| | - Torsten Schwede
- BiozentrumUniversity of BaselBaselSwitzerland
- Computational Structural BiologySIB Swiss Institute of BioinformaticsBaselSwitzerland
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3
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Maity D, Singh D, Bandhu A. Mce1R of Mycobacterium tuberculosis prefers long-chain fatty acids as specific ligands: a computational study. Mol Divers 2023; 27:2523-2543. [PMID: 36385433 DOI: 10.1007/s11030-022-10566-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 11/04/2022] [Indexed: 11/17/2022]
Abstract
The mce1 operon of Mycobacterium tuberculosis, which codes the Mce1 transporter, facilitates the transport of fatty acids. Fatty acids are one of the major sources for carbon and energy for the pathogen during its intracellular survival and pathogenicity. The mce1 operon is transcriptionally regulated by Mce1R, a VanR-type regulator, which could bind specific ligands and control the expression of the mce1 operon accordingly. This work reports computational identification of Mce1R-specific ligands. Initially by employing cavity similarity search algorithm by the ProBis server, the cavities of the proteins similar to that of Mce1R and the bound ligands were identified from which fatty acids were selected as the potential ligands. From the earlier-generated monomeric structure, the dimeric structure of Mce1R was then modeled by the GalaxyHomomer server and validated computationally to use in molecular docking and molecular dynamics simulation analysis. The fatty acid ligands were found to dock within the cavity of Mce1R and the docked complexes were subjected to molecular dynamics simulation to explore their stabilities and other dynamic properties. The data suggest that Mce1R preferably binds to long-chain fatty acids and undergoes distinct structural changes upon binding.
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Affiliation(s)
- Dipanwita Maity
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Dheeraj Singh
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Amitava Bandhu
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India.
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4
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Chen J, Fruhauf A, Fan C, Ponce J, Ueberheide B, Bhabha G, Ekiert DC. Structure of an endogenous mycobacterial MCE lipid transporter. Nature 2023; 620:445-452. [PMID: 37495693 DOI: 10.1038/s41586-023-06366-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 06/22/2023] [Indexed: 07/28/2023]
Abstract
To replicate inside macrophages and cause tuberculosis, Mycobacterium tuberculosis must scavenge a variety of nutrients from the host1,2. The mammalian cell entry (MCE) proteins are important virulence factors in M. tuberculosis1,3, where they are encoded by large gene clusters and have been implicated in the transport of fatty acids4-7 and cholesterol1,4,8 across the impermeable mycobacterial cell envelope. Very little is known about how cargos are transported across this barrier, and it remains unclear how the approximately ten proteins encoded by a mycobacterial mce gene cluster assemble to transport cargo across the cell envelope. Here we report the cryo-electron microscopy (cryo-EM) structure of the endogenous Mce1 lipid-import machine of Mycobacterium smegmatis-a non-pathogenic relative of M. tuberculosis. The structure reveals how the proteins of the Mce1 system assemble to form an elongated ABC transporter complex that is long enough to span the cell envelope. The Mce1 complex is dominated by a curved, needle-like domain that appears to be unrelated to previously described protein structures, and creates a protected hydrophobic pathway for lipid transport across the periplasm. Our structural data revealed the presence of a subunit of the Mce1 complex, which we identified using a combination of cryo-EM and AlphaFold2, and name LucB. Our data lead to a structural model for Mce1-mediated lipid import across the mycobacterial cell envelope.
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Affiliation(s)
- James Chen
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Alice Fruhauf
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Catherine Fan
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Jackeline Ponce
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University School of Medicine, New York, NY, USA
| | - Beatrix Ueberheide
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University School of Medicine, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Gira Bhabha
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA.
| | - Damian C Ekiert
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA.
- Department of Microbiology, New York University School of Medicine, New York, NY, USA.
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5
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Renau-Mínguez C, Herrero-Abadía P, Ruiz-Rodriguez P, Sentandreu V, Torrents E, Chiner-Oms Á, Torres-Puente M, Comas I, Julián E, Coscolla M. Genomic analysis of Mycobacterium brumae sustains its nonpathogenic and immunogenic phenotype. Front Microbiol 2023; 13:982679. [PMID: 36687580 PMCID: PMC9850167 DOI: 10.3389/fmicb.2022.982679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 12/06/2022] [Indexed: 01/07/2023] Open
Abstract
Mycobacterium brumae is a rapid-growing, non-pathogenic Mycobacterium species, originally isolated from environmental and human samples in Barcelona, Spain. Mycobacterium brumae is not pathogenic and it's in vitro phenotype and immunogenic properties have been well characterized. However, the knowledge of its underlying genetic composition is still incomplete. In this study, we first describe the 4 Mb genome of the M. brumae type strain ATCC 51384T assembling PacBio reads, and second, we assess the low intraspecies variability by comparing the type strain with Illumina reads from three additional strains. Mycobacterium brumae genome is composed of a circular chromosome with a high GC content of 69.2% and containing 3,791 CDSs, 97 pseudogenes, one prophage and no CRISPR loci. Mycobacterium brumae has shown no pathogenic potential in in vivo experiments, and our genomic analysis confirms its phylogenetic position with other non-pathogenic and rapid growing mycobacteria. Accordingly, we determined the absence of virulence-related genes, such as ESX-1 locus and most PE/PPE genes, among others. Although the immunogenic potential of M. brumae was proved to be as high as Mycobacterium bovis BCG, the only mycobacteria licensed to treat cancer, the genomic content of M. tuberculosis T cell and B cell antigens in M. brumae genome is considerably lower than those antigens present in M. bovis BCG genome. Overall, this work provides relevant genomic data on one of the species of the mycobacterial genus with high therapeutic potential.
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Affiliation(s)
| | - Paula Herrero-Abadía
- Genetics and Microbiology Department, Faculty of Biosciences, Autonomous University of Barcelona, Barcelona, Spain
| | | | - Vicente Sentandreu
- Genomics Unit, Central Service for Experimental Research (SCSIE), University of Valencia, Burjassot, Spain
| | - Eduard Torrents
- Bacterial Infections and Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- Microbiology Section, Department of Genetics, Microbiology, and Statistics, Biology Faculty, Universitat de Barcelona, Barcelona, Spain
| | | | | | - Iñaki Comas
- Instituto de Biomedicina de Valencia (IBV), CSIC, Valencia, Spain
| | - Esther Julián
- Genetics and Microbiology Department, Faculty of Biosciences, Autonomous University of Barcelona, Barcelona, Spain
| | - Mireia Coscolla
- I2SysBio, University of Valencia-FISABIO Joint Unit, Paterna, Spain
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6
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Nishimura N, Tomiyasu N, Torigoe S, Mizuno S, Fukano H, Ishikawa E, Katano H, Hoshino Y, Matsuo K, Takahashi M, Izumi Y, Bamba T, Akashi K, Yamasaki S. Mycobacterial mycolic acids trigger inhibitory receptor Clec12A to suppress host immune responses. Tuberculosis (Edinb) 2023; 138:102294. [PMID: 36542980 DOI: 10.1016/j.tube.2022.102294] [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: 10/18/2022] [Revised: 12/05/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022]
Abstract
Mycobacteria often cause chronic infection. To establish persistence in the host, mycobacteria need to evade host immune responses. However, the molecular mechanisms underlying the evasion strategy are not fully understood. Here, we demonstrate that mycobacterial cell wall lipids trigger an inhibitory receptor to suppress host immune responses. Mycolic acids are major cell wall components and are essential for survival of mycobacteria. By screening inhibitory receptors that react with mycobacterial lipids, we found that mycolic acids from various mycobacterial species bind to mouse Clec12A, and more potently to human Clec12A. Clec12A is a conserved inhibitory C-type lectin receptor containing immunoreceptor tyrosine-based inhibitory motif (ITIM). Innate immune responses, such as MCP-1 production, and PPD-specific recall T cell responses were augmented in Clec12A-deficient mice after infection. In contrast, human Clec12A transgenic mice were susceptible to infection with M. tuberculosis. These results suggest that mycobacteria dampen host immune responses by hijacking an inhibitory host receptor through their specific and essential lipids, mycolic acids. The blockade of this interaction might provide a therapeutic option for the treatment or prevention of mycobacterial infection.
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Affiliation(s)
- Naoya Nishimura
- Department of Molecular Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, 565-0871, Japan; Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Noriyuki Tomiyasu
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Shota Torigoe
- Laboratory of Molecular Immunology, Immunology Frontier Research Center, Osaka University, Suita, 565-0871, Japan; Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, 189-0002, Japan; Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, 162-8640, Japan
| | - Satoru Mizuno
- Research and Development Department, Japan BCG Laboratory, Tokyo, 204-0022, Japan
| | - Hanako Fukano
- Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, 189-0002, Japan
| | - Eri Ishikawa
- Department of Molecular Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, 565-0871, Japan; Laboratory of Molecular Immunology, Immunology Frontier Research Center, Osaka University, Suita, 565-0871, Japan
| | - Harutaka Katano
- Department of Pathology, National Institute of Infectious Disease, Tokyo, 162-8640, Japan
| | - Yoshihiko Hoshino
- Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, 189-0002, Japan
| | - Kazuhiro Matsuo
- Research and Development Department, Japan BCG Laboratory, Tokyo, 204-0022, Japan
| | - Masatomo Takahashi
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8582, Japan; Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582, Japan
| | - Yoshihiro Izumi
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8582, Japan; Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582, Japan.
| | - Takeshi Bamba
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8582, Japan; Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582, Japan
| | - Koichi Akashi
- Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Sho Yamasaki
- Department of Molecular Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, 565-0871, Japan; Laboratory of Molecular Immunology, Immunology Frontier Research Center, Osaka University, Suita, 565-0871, Japan; Center for Infectious Disease Education and Research, Osaka University (CiDER), Suita, 565-0871, Japan; Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba, 260-8673, Japan; Division of Molecular Design, Research Center for Systems Immunology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582, Japan.
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7
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Vieni C, Coudray N, Isom GL, Bhabha G, Ekiert DC. Role of Ring6 in the function of the E. coli MCE protein LetB. J Mol Biol 2022; 434:167463. [PMID: 35077766 PMCID: PMC9112829 DOI: 10.1016/j.jmb.2022.167463] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/15/2022] [Accepted: 01/18/2022] [Indexed: 10/19/2022]
Abstract
LetB is a tunnel-forming protein found in the cell envelope of some double-membraned bacteria, and is thought to be important for the transport of lipids between the inner and outer membranes. In Escherichia coli the LetB tunnel is formed from a stack of seven rings (Ring1 - Ring7), in which each ring is composed of a homo-hexameric assembly of MCE domains. The primary sequence of each MCE domain of the LetB protein is substantially divergent from the others, making each MCE ring unique in nature. The role of each MCE domain and how it contributes to the function of LetB is not well understood. Here we probed the importance of each MCE ring for the function of LetB, using a combination of bacterial growth assays and cryo-EM. Surprisingly, we find that ΔRing3 and ΔRing6 mutants, in which Ring3 and Ring6 have been deleted, confer increased resistance to membrane perturbing agents. Specific mutations in the pore-lining loops of Ring6 similarly confer increased resistance. A cryo-EM structure of the ΔRing6 mutant shows that despite the absence of Ring6, which leads to a shorter assembly, the overall architecture is maintained, highlighting the modular nature of MCE proteins. Previous work has shown that Ring6 is dynamic and in its closed state, may restrict the passage of substrate through the tunnel. Our work suggests that removal of Ring6 may relieve this restriction. The deletion of Ring6 combined with mutations in the pore-lining loops leads to a model for the tunnel gating mechanism of LetB. Together, these results provide insight into the functional roles of individual MCE domains and pore-lining loops in the LetB protein.
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8
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Mycobacterial MCE proteins as transporters that control lipid homeostasis of the cell wall. Tuberculosis (Edinb) 2021; 132:102162. [PMID: 34952299 DOI: 10.1016/j.tube.2021.102162] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/30/2021] [Accepted: 12/10/2021] [Indexed: 01/05/2023]
Abstract
Mammalian cell entry (mce) genes are not only present in genomes of pathogenic mycobacteria, including Mycobacterium tuberculosis (the causative agent of tuberculosis), but also in saprophytic and opportunistic mycobacterial species. MCE are conserved cell-wall proteins encoded by mce operons, which maintain an identical structure in all mycobacteria: two yrbE genes (A and B) followed by six mce genes (A, B, C, D, E and F). Although these proteins are known to participate in the virulence of pathogenic mycobacteria, the presence of the operons in nonpathogenic mycobacteria and other bacteria indicates that they play another role apart from host cell invasion. In this respect, more recent studies suggest that they are functionally similar to ABC transporters and form part of lipid transporters in Actinobacteria. To date, most reviews on mce operons in the literature discuss their role in virulence. However, according to data from transcriptional studies, mce genes, particularly the mce1 and mce4 operons, modify their expression according to the carbon source and upon hypoxia, starvation, surface stress and oxidative stress; which suggests a role of MCE proteins in the response of Mycobacteria to external stressors. In addition to these data, this review also summarizes the studies demonstrating the role of MCE proteins as lipid transporters as well as the relevance of their transport function in the interaction of pathogenic Mycobacteria with the hosts. Altogether, the evidence to date would indicate that MCE proteins participate in the response to the stress conditions that mycobacteria encounter during infection, by participating in the cell wall remodelling and possibly contributing to lipid homeostasis.
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9
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ATP disrupts lipid-binding equilibrium to drive retrograde transport critical for bacterial outer membrane asymmetry. Proc Natl Acad Sci U S A 2021; 118:2110055118. [PMID: 34873038 DOI: 10.1073/pnas.2110055118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2021] [Indexed: 12/15/2022] Open
Abstract
The hallmark of the gram-negative bacterial envelope is the presence of the outer membrane (OM). The OM is asymmetric, comprising lipopolysaccharides (LPS) in the outer leaflet and phospholipids (PLs) in the inner leaflet; this critical feature confers permeability barrier function against external insults, including antibiotics. To maintain OM lipid asymmetry, the OmpC-Mla system is believed to remove aberrantly localized PLs from the OM and transport them to the inner membrane (IM). Key to the system in driving lipid trafficking is the MlaFEDB ATP-binding cassette transporter complex in the IM, but mechanistic details, including transport directionality, remain enigmatic. Here, we develop a sensitive point-to-point in vitro lipid transfer assay that allows direct tracking of [14C]-labeled PLs between the periplasmic chaperone MlaC and MlaFEDB reconstituted into nanodiscs. We reveal that MlaC spontaneously transfers PLs to the IM transporter in an MlaD-dependent manner that can be further enhanced by coupled ATP hydrolysis. In addition, we show that MlaD is important for modulating productive coupling between ATP hydrolysis and such retrograde PL transfer. We further demonstrate that spontaneous PL transfer also occurs from MlaFEDB to MlaC, but such anterograde movement is instead abolished by ATP hydrolysis. Our work uncovers a model where PLs reversibly partition between two lipid-binding sites in MlaC and MlaFEDB, and ATP binding and/or hydrolysis shift this equilibrium to ultimately drive retrograde PL transport by the OmpC-Mla system. These mechanistic insights will inform future efforts toward discovering new antibiotics against gram-negative pathogens.
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10
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Dokic A, Peterson E, Arrieta-Ortiz ML, Pan M, Di Maio A, Baliga N, Bhatt A. Mycobacterium abscessus biofilms produce an extracellular matrix and have a distinct mycolic acid profile. Cell Surf 2021; 7:100051. [PMID: 33912773 PMCID: PMC8066798 DOI: 10.1016/j.tcsw.2021.100051] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/25/2021] [Accepted: 03/26/2021] [Indexed: 02/06/2023] Open
Abstract
A non-tuberculous mycobacterium, Mycobacterium abscessus is an emerging opportunistic pathogen associated with difficult to treat pulmonary infections, particularly in patients suffering from cystic fibrosis. It is capable of forming biofilms in vitro that result in an increase of already high levels of antibiotic resistance in this bacterium. Evidence that M. abscessus forms biofilm-like microcolonies in patient lungs and on medical devices further implicated the need to investigate this biofilm in detail. Therefore, in this study we characterized the M. abscessus pellicular biofilm, formed on a liquid-air interface, by studying its molecular composition, and its transcriptional profile in comparison to planktonic cells. Using scanning electron micrographs and fluorescence microscopy, we showed that M. abscessus biofilms produce an extracellular matrix composed of lipids, proteins, carbohydrates and extracellular DNA. Transcriptomic analysis of biofilms revealed an upregulation of pathways involved in the glyoxylate shunt, redox metabolism and mycolic acid biosynthesis. Genes involved in elongation and desaturation of mycolic acids were highly upregulated in biofilms and, mirroring those findings, biochemical analysis of mycolates revealed molecular changes and an increase in mycolic acid chain length. Together these results give us an insight into the complex structure of M. abscessus biofilms, the understanding of which may be adapted for clinical use in treatment of biofilm infections, including strategies for dispersing the extracellular matrix, allowing antibiotics to gain access to bacteria within the biofilm.
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Affiliation(s)
- Anja Dokic
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | | | | | - Min Pan
- Institute for Systems Biology, Seattle, WA 98109 USA
| | - Alessandro Di Maio
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Nitin Baliga
- Institute for Systems Biology, Seattle, WA 98109 USA
| | - Apoorva Bhatt
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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11
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Asthana P, Singh D, Pedersen JS, Hynönen MJ, Sulu R, Murthy AV, Laitaoja M, Jänis J, Riley LW, Venkatesan R. Structural insights into the substrate-binding proteins Mce1A and Mce4A from Mycobacterium tuberculosis. IUCRJ 2021; 8:757-774. [PMID: 34584737 PMCID: PMC8420772 DOI: 10.1107/s2052252521006199] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/15/2021] [Indexed: 05/28/2023]
Abstract
Mycobacterium tuberculosis (Mtb), which is responsible for more than a million deaths annually, uses lipids as the source of carbon and energy for its survival in the latent phase of infection. Mtb cannot synthesize all of the lipid molecules required for its growth and pathogenicity. Therefore, it relies on transporters such as the mammalian cell entry (Mce) complexes to import lipids from the host across the cell wall. Despite their importance for the survival and pathogenicity of Mtb, information on the structural properties of these proteins is not yet available. Each of the four Mce complexes in Mtb (Mce1-4) comprises six substrate-binding proteins (SBPs; MceA-F), each of which contains four conserved domains (N-terminal transmembrane, MCE, helical and C-terminal unstructured tail domains). Here, the properties of the various domains of Mtb Mce1A and Mce4A, which are involved in the import of mycolic/fatty acids and cholesterol, respectively, are reported. In the crystal structure of the MCE domain of Mce4A (MtMce4A39-140) a domain-swapped conformation is observed, whereas solution studies, including small-angle X-ray scattering (SAXS), indicate that all Mce1A and Mce4A domains are predominantly monomeric. Further, structural comparisons show interesting differences from the bacterial homologs MlaD, PqiB and LetB, which form homohexamers when assembled as functional transporter complexes. These data, and the fact that there are six SBPs in each Mtb mce operon, suggest that the MceA-F SBPs from Mce1-4 may form heterohexamers. Also, interestingly, the purification and SAXS analysis showed that the helical domains interact with the detergent micelle, suggesting that when assembled the helical domains of MceA-F may form a hydrophobic pore for lipid transport, as observed in EcPqiB. Overall, these data highlight the unique structural properties of the Mtb Mce SBPs.
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Affiliation(s)
- Pooja Asthana
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Dhirendra Singh
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Mikko J. Hynönen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Ramita Sulu
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Abhinandan V. Murthy
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Mikko Laitaoja
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Janne Jänis
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Lee W. Riley
- School of Public Health, University of California, Berkeley, California, USA
| | - Rajaram Venkatesan
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
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12
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Jackson M, Stevens CM, Zhang L, Zgurskaya HI, Niederweis M. Transporters Involved in the Biogenesis and Functionalization of the Mycobacterial Cell Envelope. Chem Rev 2021; 121:5124-5157. [PMID: 33170669 PMCID: PMC8107195 DOI: 10.1021/acs.chemrev.0c00869] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The biology of mycobacteria is dominated by a complex cell envelope of unique composition and structure and of exceptionally low permeability. This cell envelope is the basis of many of the pathogenic features of mycobacteria and the site of susceptibility and resistance to many antibiotics and host defense mechanisms. This review is focused on the transporters that assemble and functionalize this complex structure. It highlights both the progress and the limits of our understanding of how (lipo)polysaccharides, (glyco)lipids, and other bacterial secretion products are translocated across the different layers of the cell envelope to their final extra-cytoplasmic location. It further describes some of the unique strategies evolved by mycobacteria to import nutrients and other products through this highly impermeable barrier.
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Affiliation(s)
- Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Casey M. Stevens
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Lei Zhang
- Department of Microbiology, University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294, USA
| | - Helen I. Zgurskaya
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294, USA
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13
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TREM2 is a receptor for non-glycosylated mycolic acids of mycobacteria that limits anti-mycobacterial macrophage activation. Nat Commun 2021; 12:2299. [PMID: 33863908 PMCID: PMC8052348 DOI: 10.1038/s41467-021-22620-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 03/17/2021] [Indexed: 01/10/2023] Open
Abstract
Mycobacterial cell-wall glycolipids elicit an anti-mycobacterial immune response via FcRγ-associated C-type lectin receptors, including Mincle, and caspase-recruitment domain family member 9 (CARD9). Additionally, mycobacteria harbor immuno-evasive cell-wall lipids associated with virulence and latency; however, a mechanism of action is unclear. Here, we show that the DAP12-associated triggering receptor expressed on myeloid cells 2 (TREM2) recognizes mycobacterial cell-wall mycolic acid (MA)-containing lipids and suggest a mechanism by which mycobacteria control host immunity via TREM2. Macrophages respond to glycosylated MA-containing lipids in a Mincle/FcRγ/CARD9-dependent manner to produce inflammatory cytokines and recruit inducible nitric oxide synthase (iNOS)-positive mycobactericidal macrophages. Conversely, macrophages respond to non-glycosylated MAs in a TREM2/DAP12-dependent but CARD9-independent manner to recruit iNOS-negative mycobacterium-permissive macrophages. Furthermore, TREM2 deletion enhances Mincle-induced macrophage activation in vitro and inflammation in vivo and accelerates the elimination of mycobacterial infection, suggesting that TREM2-DAP12 signaling counteracts Mincle-FcRγ-CARD9-mediated anti-mycobacterial immunity. Mycobacteria, therefore, harness TREM2 for immune evasion. Mycobacterial cell wall lipids can drive immunoevasion, but underlying mechanisms are incompletely understood. Here the authors show TREM2 is a pattern recognition receptor that binds non-glycosylated mycolic acid-containing lipids and inhibits Mincle-induced anti-mycobacterial macrophage responses.
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14
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Abrahams KA, Besra GS. Synthesis and recycling of the mycobacterial cell envelope. Curr Opin Microbiol 2021; 60:58-65. [PMID: 33610125 PMCID: PMC8035080 DOI: 10.1016/j.mib.2021.01.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/14/2021] [Accepted: 01/27/2021] [Indexed: 02/07/2023]
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of the disease tuberculosis, is a recognised global health concern. The efficacy of the current treatment regime is under threat due to the emergence of antibiotic resistance, directing an urgent requirement for the discovery of new anti-tubercular agents and drug targets. The mycobacterial cell wall is a well-validated drug target for Mtb and is composed of three adaptive macromolecular structures, peptidoglycan, arabinogalactan and mycolic acids, an array of complex lipids and carbohydrates. The majority of the enzymes involved in cell wall synthesis have been established, whilst studies directed towards the mechanisms of remodelling and recycling have been neglected. This review briefly describes mycobacterial cell wall synthesis, and focuses on aspects of remodelling and recycling, thus highlighting opportunities for future research.
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Affiliation(s)
- Katherine A Abrahams
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Gurdyal S Besra
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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15
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Abstract
The mycomembrane layer of the mycobacterial cell envelope is a barrier to environmental, immune, and antibiotic insults. There is considerable evidence of mycomembrane plasticity during infection and in response to host-mimicking stresses. The mycomembrane layer of the mycobacterial cell envelope is a barrier to environmental, immune, and antibiotic insults. There is considerable evidence of mycomembrane plasticity during infection and in response to host-mimicking stresses. Since mycobacteria are resource and energy limited under these conditions, it is likely that remodeling has distinct requirements from those of the well-characterized biosynthetic program that operates during unrestricted growth. Unexpectedly, we found that mycomembrane remodeling in nutrient-starved, nonreplicating mycobacteria includes synthesis in addition to turnover. Mycomembrane synthesis under these conditions occurs along the cell periphery, in contrast to the polar assembly of actively growing cells, and both liberates and relies on the nonmammalian disaccharide trehalose. In the absence of trehalose recycling, de novo trehalose synthesis fuels mycomembrane remodeling. However, mycobacteria experience ATP depletion, enhanced respiration, and redox stress, hallmarks of futile cycling and the collateral dysfunction elicited by some bactericidal antibiotics. Inefficient energy metabolism compromises the survival of trehalose recycling mutants in macrophages. Our data suggest that trehalose recycling alleviates the energetic burden of mycomembrane remodeling under stress. Cell envelope recycling pathways are emerging targets for sensitizing resource-limited bacterial pathogens to host and antibiotic pressure.
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16
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Molecular Cloning, Purification and Characterization of Mce1R of Mycobacterium tuberculosis. Mol Biotechnol 2021; 63:200-220. [PMID: 33423211 DOI: 10.1007/s12033-020-00293-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2020] [Indexed: 10/22/2022]
Abstract
The mce1 operon of Mycobacterium tuberculosis, important for lipid metabolism/transport, host cell invasion, modulation of host immune response and pathogenicity, is under the transcriptional control of Mce1R. Hence characterizing Mce1R is an important step for novel anti-tuberculosis drug discovery. The present study reports functional and in silico characterization of Mce1R. In this work, we have computationally modeled the structure of Mce1R and have validated the structure by computational and experimental methods. Mce1R has been shown to harbor the canonical VanR-like structure with a flexible N-terminal 'arm', carrying conserved positively charged residues, most likely involved in the operator DNA binding. The mce1R gene has been cloned, expressed, purified and its DNA-binding activity has been measured in vitro. The Kd value for Mce1R-operator DNA interaction has been determined to be 0.35 ± 0.02 µM which implies that Mce1R binds to DNA with moderate affinity compared to the other FCD family of regulators. So far, this is the first report for measuring the DNA-binding affinity of any VanR-type protein. Despite significant sequence similarity at the N-terminal domain, the wHTH motif of Mce1R exhibits poor conservancy of amino acid residues, critical for DNA-binding, thus results in moderate DNA-binding affinity. The N-terminal DNA-binding domain is structurally dynamic while the C-terminal domain showed significant stability and such profile of structural dynamics is most likely to be preserved in the structural orthologs of Mce1R. In addition to this, a cavity has been detected in the C-terminal domain of Mce1R which contains a few conserved residues. Comparison with other FCD family of regulators suggests that most of the conserved residues might be critical for binding to specific ligand. The max pKd value and drug score for the cavity are estimated to be 9.04 and 109 respectively suggesting that the cavity represents a suitable target site for novel anti-tuberculosis drug discovery approaches.
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17
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Isom GL, Coudray N, MacRae MR, McManus CT, Ekiert DC, Bhabha G. LetB Structure Reveals a Tunnel for Lipid Transport across the Bacterial Envelope. Cell 2021; 181:653-664.e19. [PMID: 32359438 DOI: 10.1016/j.cell.2020.03.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/22/2019] [Accepted: 03/11/2020] [Indexed: 01/20/2023]
Abstract
Gram-negative bacteria are surrounded by an outer membrane composed of phospholipids and lipopolysaccharide, which acts as a barrier and contributes to antibiotic resistance. The systems that mediate phospholipid trafficking across the periplasm, such as MCE (Mammalian Cell Entry) transporters, have not been well characterized. Our ~3.5 Å cryo-EM structure of the E. coli MCE protein LetB reveals an ~0.6 megadalton complex that consists of seven stacked rings, with a central hydrophobic tunnel sufficiently long to span the periplasm. Lipids bind inside the tunnel, suggesting that it functions as a pathway for lipid transport. Cryo-EM structures in the open and closed states reveal a dynamic tunnel lining, with implications for gating or substrate translocation. Our results support a model in which LetB establishes a physical link between the two membranes and creates a hydrophobic pathway for the translocation of lipids across the periplasm.
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Affiliation(s)
- Georgia L Isom
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Nicolas Coudray
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA; Applied Bioinformatics Laboratories, New York University School of Medicine, New York, NY, USA
| | - Mark R MacRae
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Collin T McManus
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Damian C Ekiert
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA; Department of Microbiology, New York University School of Medicine, New York, NY, USA.
| | - Gira Bhabha
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA.
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18
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Fang H, Xu JB, Nie Y, Wu XL. Pan-genomic analysis reveals that the evolution of Dietzia species depends on their living habitats. Environ Microbiol 2020; 23:861-877. [PMID: 32715552 DOI: 10.1111/1462-2920.15176] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/20/2020] [Accepted: 07/23/2020] [Indexed: 12/14/2022]
Abstract
The bacterial genus Dietzia is widely distributed in various environments. The genomes of 26 diverse strains of Dietzia, including almost all the type strains, were analysed in this study. This analysis revealed a lipid metabolism gene richness, which could explain the ability of Dietzia to live in oil related environments. The pan-genome consists of 83,976 genes assigned into 10,327 gene families, 792 of which are shared by all the genomes of Dietzia. Mathematical extrapolation of the data suggests that the Dietzia pan-genome is open. Both gene duplication and gene loss contributed to the open pan-genome, while horizontal gene transfer was limited. Dietzia strains primarily gained their diverse metabolic capacity through more ancient gene duplications. Phylogenetic analysis of Dietzia isolated from aquatic and terrestrial environments showed two distinct clades from the same ancestor. The genome sizes of Dietzia strains from aquatic environments were significantly larger than those from terrestrial environments, which was mainly due to the occurrence of more gene loss events during the evolutionary progress of the strains from terrestrial environments. The evolutionary history of Dietzia was tightly coupled to environmental conditions, and iron concentrations should be one of the key factors shaping the genomes of the Dietzia lineages.
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Affiliation(s)
- Hui Fang
- College of Engineering, Peking University, Beijing, 100871, China
| | - Jin-Bo Xu
- College of Engineering, Peking University, Beijing, 100871, China
| | - Yong Nie
- College of Engineering, Peking University, Beijing, 100871, China
| | - Xiao-Lei Wu
- College of Engineering, Peking University, Beijing, 100871, China.,Institute of Ocean Research, Peking University, Beijing, 100871, China
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19
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Petrilli JD, Müller I, Araújo LE, Cardoso TM, Carvalho LP, Barros BC, Teixeira M, Arruda S, Riley LW, Queiroz A. Differential Host Pro-Inflammatory Response to Mycobacterial Cell Wall Lipids Regulated by the Mce1 Operon. Front Immunol 2020; 11:1848. [PMID: 32973761 PMCID: PMC7461851 DOI: 10.3389/fimmu.2020.01848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 07/09/2020] [Indexed: 11/17/2022] Open
Abstract
The cell wall of wild-type (WT) Mycobacterium tuberculosis (Mtb), an etiologic agent of tuberculosis (TB) and a Mtb strain disrupted in a 13-gene operon mce1 (Δmce1) varies by more than 400 lipid species. Here, we examined Mtb lipid-induced response in murine macrophage, as well as in human T-cell subpopulations in order to gain an insight into how changes in cell wall lipid composition may modulate host immune response. Relative to WT Mtb cell wall lipids, the non-polar lipid extracts from Δmce1 enhanced the mRNA expression of lipid-sense nuclear receptors TR4 and PPAR-γ and dampened the macrophage expression of genes encoding TNF-α, IL-6, and IL-1β. Relative to untreated control, WT lipid-pre-stimulated macrophages from healthy individuals induced a higher level of CD4−CD8− double negative T-cells (DN T-cells) producing TNF-α. Conversely, compared to WT, stimulation with Δmce1 lipids induced higher mean fluorescence intensity (MFI) in IL-10-producing DN T cells. Mononuclear cells from TB patients stimulated with WT Mtb lipids induced an increased production of TNF-α by CD8+ lymphocytes. Taken together, these observations suggest that changes in mce1 operon expression during a course of infection may serve as a strategy by Mtb to evade the host pro-inflammatory responses.
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Affiliation(s)
- Jéssica D Petrilli
- Laboratorio Avançado de Saúde Pública, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Igor Müller
- Laboratorio Avançado de Saúde Pública, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Luana E Araújo
- Laboratorio Avançado de Saúde Pública, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Thiago M Cardoso
- Laboratório de Pesquisa Clínica, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Lucas P Carvalho
- Laboratório de Pesquisa Clínica, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Bruna C Barros
- Laboratorio Avançado de Saúde Pública, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Maurício Teixeira
- Laboratório de Pesquisa Clínica, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Sérgio Arruda
- Laboratorio Avançado de Saúde Pública, Instituto Gonçalo Moniz, Salvador, Brazil
| | - Lee W Riley
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, CA, United States
| | - Adriano Queiroz
- Laboratorio Avançado de Saúde Pública, Instituto Gonçalo Moniz, Salvador, Brazil
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20
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Luo X, Pan J, Meng Q, Huang J, Wang W, Zhang N, Wang G. High-Throughput Screen for Cell Wall Synthesis Network Module in Mycobacterium tuberculosis Based on Integrated Bioinformatics Strategy. Front Bioeng Biotechnol 2020; 8:607. [PMID: 32695753 PMCID: PMC7338375 DOI: 10.3389/fbioe.2020.00607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 05/18/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Mycobacterium tuberculosis is one of the deadliest pathogens in humans. Co-infection of M. tuberculosis with HIV and the emergence of multi-drug-resistant tuberculosis (TB) constitute a serious global threat. However, no effective anti-TB drugs are available, with the exception of first-line drugs such as isoniazid. The cell wall of M. tuberculosis, which is primarily responsible for the lack of effective anti-TB drugs and the escape of the bacteria from host immunity, is an important drug target. The core components of the cell wall of M. tuberculosis are peptidoglycan, arabinogalactan, and mycotic acid. However, the functional genome and metabolic regulation pathways for the M. tuberculosis cell wall are still unknown. In this study, we used the biclustering algorithm integrated into cMonkey, sequence alignment, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and other bioinformatics methods to scan the whole genome of M. tuberculosis as well as to identify and statistically analyze the genes related to the synthesis of the M. tuberculosis cell wall. METHOD We performed high-throughput genome-wide screening for M. tuberculosis using Biocarta, KEGG, National Cancer Institute Pathway Interaction Database (NCI-PID), HumanCyc, and Reactome. We then used the Database of Origin and Registration (DOOR) established in our laboratory to classify the collection of operons for M. tuberculosis cell wall synthetic genes. We used the cMonkey double clustering algorithm to perform clustering analysis on the gene expression profile of M. tuberculosis for cell wall synthesis. Finally, we visualized the results using Cytoscape. RESULT AND CONCLUSION Through bioinformatics and statistical analyses, we identified 893 M. tuberculosis H37Rv cell wall synthesis genes, distributed in 20 pathways, involved in 46 different functions related to cell wall synthesis, and clustered in 386 modules. We identified important pivotal genes and proteins in the cell wall synthesis pathway such as murA, a class of operons containing genes involved in cell wall synthesis such as ID6951, and a class of operons indispensable for the survival of the bacteria. In addition, we found 41 co-regulatory modules for cell wall synthesis and five co-expression networks of molecular complexes involved in peptidoglycan biosynthesis, membrane transporter synthesis, and other cell wall processes.
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Affiliation(s)
- Xizi Luo
- Department of Pathogenobiology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Jiahui Pan
- Department of Pathogenobiology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Qingyu Meng
- Department of Pathogenobiology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Juanjuan Huang
- Department of Pathogenobiology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Wenfang Wang
- Department of Pathogenobiology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Nan Zhang
- College of Mathematics, Jilin University, Changchun, China
| | - Guoqing Wang
- Department of Pathogenobiology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
- *Correspondence: Guoqing Wang,
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21
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Techniques to Understand Mycobacterial Lipids and Use of Lipid-Based Nanoformulations for Tuberculosis Management. Nanobiomedicine (Rij) 2020. [DOI: 10.1007/978-981-32-9898-9_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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22
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Microenvironment of Mycobacterium smegmatis Culture to Induce Cholesterol Consumption Does Cell Wall Remodeling and Enables the Formation of Granuloma-Like Structures. BIOMED RESEARCH INTERNATIONAL 2019; 2019:1871239. [PMID: 31119154 PMCID: PMC6500705 DOI: 10.1155/2019/1871239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/11/2019] [Accepted: 03/17/2019] [Indexed: 11/22/2022]
Abstract
Pathogenic species of mycobacteria are known to use the host cholesterol during lung infection as an alternative source of carbon and energy. Mycobacteria culture in minimal medium (MM) has been used as an in vitro experimental model to study the consumption of exogenous cholesterol. Once in MM, different species of mycobacteria start to consume the cholesterol and initiate transcriptional and metabolic adaptations, upregulating the enzymes of the methylcitrate cycle (MCC) and accumulating a variety of primary metabolites that are known to be important substrates for cell wall biosynthesis. We hypothesized that stressful pressure of cultures in MM is able to induce critical adaptation for the bacteria which win the infection. To identify important modifications in the biosynthesis of the cell wall, we cultured the fast-growing and nonpathogenic Mycobacterium smegmatis in MM supplemented with or without glycerol and/or cholesterol. Different from the culture in complete medium Middlebrook 7H9 broth, the bacteria when cultured in MM decreased growth and changed in the accumulation of cell wall molecules. However, the supplementation of MM with glycerol and/or cholesterol recovered the accumulation of phosphatidylinositol mannosides (PIMs) and other phospholipids but maintained growth deceleration. The biosynthesis of lipomannan (LM) and of lipoarabinomannan (LAM) was significantly modulated after culture in MM, independently of glycerol and/or cholesterol supplementation, where LM size was decreased (LM13-25KDa) and LAM increased (LAM37-100KDa), when compared these molecules after bacteria culture in complete medium (LM17-25KDa and LAM37-50KDa). These changes modified the cell surface hydrophobicity and susceptibility against H2O2. The infection of J774 macrophages with M. smegmatis, after culture in MM, induced the formation of granuloma-like structures, while supplementation with cholesterol induced the highest rate of formation of these structures. Taken together, our results identify critical changes in mycobacterial cell wall molecules after culture in MM that induces cholesterol accumulation, helping the mycobacteria to increase their capacity to form granuloma-like structures.
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Chakraborty P, Kumar A. The extracellular matrix of mycobacterial biofilms: could we shorten the treatment of mycobacterial infections? MICROBIAL CELL 2019; 6:105-122. [PMID: 30740456 PMCID: PMC6364259 DOI: 10.15698/mic2019.02.667] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A number of non-tuberculous mycobacterium species are opportunistic pathogens and ubiquitously form biofilms. These infections are often recalcitrant to treatment and require therapy with multiple drugs for long duration. The biofilm resident bacteria also display phenotypic drug tolerance and thus it has been hypothesized that the drug unresponsiveness in vivo could be due to formation of biofilms inside the host. We have discussed the biofilms of several pathogenic non-tuberculous mycobacterium (NTM) species in context to the in vivo pathologies. Besides pathogenic NTMs, Mycobacterium smegmatis is often used as a model organism for understanding mycobacterial physiology and has been studied extensively for understanding the mycobacterial biofilms. A number of components of the mycobacterial cell wall such as glycopeptidolipids, short chain mycolic acids, monomeromycolyl diacylglycerol, etc. have been shown to play an important role in formation of pellicle biofilms. It shall be noted that these components impart a hydrophobic character to the mycobacterial cell surface that facilitates cell to cell interaction. However, these components are not necessarily the constituents of the extracellular matrix of mycobacterial biofilms. In the end, we have described the biofilms of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis. Three models of Mtb biofilm formation have been proposed to study the factors regulating biofilm formation, the physiology of the resident bacteria, and the nature of the biomaterial that holds these bacterial masses together. These models include pellicle biofilms formed at the liquid-air interface of cultures, leukocyte lysate-induced biofilms, and thiol reductive stressinduced biofilms. All the three models offer their own advantages in the study of Mtb biofilms. Interestingly, lipids (mainly keto-mycolic acids) are proposed to be the primary component of extracellular polymeric substance (EPS) in the pellicle biofilm, whereas the leukocyte lysate-induced and thiol reductive stress-induced biofilms possess polysaccharides as the primary component of EPS. Both models also contain extracellular DNA in the EPS. Interestingly, thiol reductive stressinduced Mtb biofilms are held together by cellulose and yet unidentified structural proteins. We believe that a better understanding of the EPS of Mtb biofilms and the physiology of the resident bacteria will facilitate the development of shorter regimen for TB treatment.
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Affiliation(s)
- Poushali Chakraborty
- Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh, India 160036
| | - Ashwani Kumar
- Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh, India 160036.,CSIR-Academy of Scientific & Innovative Research (AcSIR), Council of Scientific & Industrial Research, New Delhi-110001
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Advani J, Verma R, Chatterjee O, Devasahayam Arokia Balaya R, Najar MA, Ravishankara N, Suresh S, Pachori PK, Gupta UD, Pinto SM, Chauhan DS, Tripathy SP, Gowda H, Prasad TK. Rise of Clinical Microbial Proteogenomics: A Multiomics Approach to Nontuberculous Mycobacterium—The Case ofMycobacterium abscessusUC22. ACTA ACUST UNITED AC 2019; 23:1-16. [DOI: 10.1089/omi.2018.0116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Jayshree Advani
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Manipal Academy of Higher Education, Manipal, India
| | - Renu Verma
- Institute of Bioinformatics, International Technology Park, Bangalore, India
| | - Oishi Chatterjee
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, India
| | - Rex Devasahayam Arokia Balaya
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Mohd Altaf Najar
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Namitha Ravishankara
- Department of Biotechnology, M.S. Ramaiah Institute of Technology, Bangalore, India
| | - Sneha Suresh
- Department of Biotechnology, M.S. Ramaiah Institute of Technology, Bangalore, India
| | - Praveen Kumar Pachori
- Department of Microbiology and Molecular Biology, ICMR-National JALMA Institute for Leprosy & Other Mycobacterial Diseases, Agra, India
| | - Umesh D. Gupta
- Department of Microbiology and Molecular Biology, ICMR-National JALMA Institute for Leprosy & Other Mycobacterial Diseases, Agra, India
| | - Sneha M. Pinto
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Devendra S. Chauhan
- Department of Microbiology and Molecular Biology, ICMR-National JALMA Institute for Leprosy & Other Mycobacterial Diseases, Agra, India
| | - Srikanth Prasad Tripathy
- Department of Microbiology and Molecular Biology, ICMR-National JALMA Institute for Leprosy & Other Mycobacterial Diseases, Agra, India
| | - Harsha Gowda
- Institute of Bioinformatics, International Technology Park, Bangalore, India
| | - T.S. Keshava Prasad
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
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25
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Yan S, Zhen J, Li Y, Zhang C, Stojkoska A, Lambert N, Li Q, Li P, Xie J. Mce-associated protein Rv0177 alters the cell wall structure of Mycobacterium smegmatis and promotes macrophage apoptosis via regulating the cytokines. Int Immunopharmacol 2019; 66:205-214. [DOI: 10.1016/j.intimp.2018.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 10/26/2018] [Accepted: 11/09/2018] [Indexed: 10/27/2022]
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Ghazaei C. Mycobacterium tuberculosis and lipids: Insights into molecular mechanisms from persistence to virulence. JOURNAL OF RESEARCH IN MEDICAL SCIENCES 2018; 23:63. [PMID: 30181745 PMCID: PMC6091133 DOI: 10.4103/jrms.jrms_904_17] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 04/08/2018] [Accepted: 03/10/2018] [Indexed: 11/04/2022]
Abstract
Mycobacterium tuberculosis is a causative agent of tuberculosis that causes deaths across the world. The pathogen apart from causing disease manifestations can also enter into a phase of latency to re-emerge later. Among the various factors associated with the virulence of pathogen, the lipids composing the cell wall of the bacillus have drawn much interest among. The unique composition of the cell wall composed of mycolic acid, glycolipids such as diacyltrehaloses, polyacyltrehalose, lipomannan, lipoarabinomannan (LAM), mannose-capped-LAM, sulfolipids, and trehalose-6,6'-dimycolate, all have been implicated in providing the pathogen an advantage in the host. The pathogen also alters its metabolism of fatty acids to survive the conditions in the host that is reflected in an altered cell wall composition in terms of lipids. In addition, the lipid profile of the cell wall has been shown to modulate the immune responses launched by the host, especially in the suppression, or production of inflammatory factors, cytokines, and phagocytic cells, such as dendritic cells and macrophages. Apart from M. tuberculosis, the paper also briefly looks at the role of Mycobacterium bovis and its role in tuberculosis in humans along with its lipid profile of its cell wall. This review aims to summarize the various lipids of the cell wall of M. tuberculosis along with their roles in enabling the pathogen to maintain its virulence to infect further humans and its persistence inside the host.
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Affiliation(s)
- Ciamak Ghazaei
- Department of Microbiology, University of Mohaghegh Ardabili, Ardabil, Iran
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Yousuf S, Angara RK, Roy A, Gupta SK, Misra R, Ranjan A. Mce2R/Rv0586 of Mycobacterium tuberculosis is the functional homologue of FadR E. coli. MICROBIOLOGY-SGM 2018; 164:1133-1145. [PMID: 29993358 DOI: 10.1099/mic.0.000686] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lipid metabolism is critical to Mycobacterium tuberculosis survival and infection. Unlike Escherichia coli, which has a single FadR, the M. tuberculosis genome encodes five proteins of the FadR sub-family. While the role of E. coli FadR as a regulator of fatty acid metabolism is well known, the definitive functions of M. tuberculosis FadR proteins are still under investigation. An interesting question about the M. tuberculosis FadRs remains open: which one of these proteins is the functional homologue of E. coli FadR? To address this, we have applied two different approaches. The first one was the bioinformatics approach and the second one was the classical molecular genetic approach involving complementation studies. Surprisingly, the results of these two approaches did not agree. Among the five M. tuberculosis FadRs, Rv0494 shared the highest sequence similarity with FadRE. coli and Rv0586 was the second best match. However, only Rv0586, but not Rv0494, could complement E. coli ∆fadR, indicating that Rv0586 is the M. tuberculosis functional homologue of FadRE. coli. Further studies showed that both regulators, Rv0494 and Rv0586, show similar responsiveness to LCFA, and have conserved critical residues for DNA binding. However, analysis of the operator site indicated that the inter-palindromic distance required for DNA binding differs for the two regulators. The differences in the binding site selection helped in the success of Rv0586 binding to fadB upstream over Rv0494 and may have played a critical role in complementing E. coli ∆fadR. Further, for the first time, we report the lipid-responsive nature of Rv0586.
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Affiliation(s)
- Suhail Yousuf
- 1Computational and Functional Genomics Group, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500039, India
- 2Graduate studies, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Rajendra Kumar Angara
- 1Computational and Functional Genomics Group, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500039, India
- 2Graduate studies, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Ajit Roy
- 1Computational and Functional Genomics Group, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500039, India
- 2Graduate studies, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Shailesh Kumar Gupta
- 1Computational and Functional Genomics Group, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500039, India
- 2Graduate studies, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Rohan Misra
- 1Computational and Functional Genomics Group, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500039, India
- 2Graduate studies, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Akash Ranjan
- 1Computational and Functional Genomics Group, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500039, India
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28
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Wilburn KM, Fieweger RA, VanderVen BC. Cholesterol and fatty acids grease the wheels of Mycobacterium tuberculosis pathogenesis. Pathog Dis 2018; 76:4931720. [PMID: 29718271 PMCID: PMC6251666 DOI: 10.1093/femspd/fty021] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 03/06/2018] [Indexed: 01/23/2023] Open
Abstract
Tuberculosis is a distinctive disease in which the causative agent, Mycobacterium tuberculosis, can persist in humans for decades by avoiding clearance from host immunity. During infection, M. tuberculosis maintains viability by extracting and utilizing essential nutrients from the host, and this is a prerequisite for all of the pathogenic activities that are deployed by the bacterium. In particular, M. tuberculosis preferentially acquires and metabolizes host-derived lipids (fatty acids and cholesterol), and the bacterium utilizes these substrates to cause and maintain disease. In this review, we discuss our current understanding of lipid utilization by M. tuberculosis, and we describe how these pathways promote pathogenesis to fuel metabolic processes in the bacillus. Finally, we highlight weaknesses in these pathways that potentially can be targeted for drug discovery.
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Affiliation(s)
- Kaley M Wilburn
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14850, USA
| | - Rachael A Fieweger
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14850, USA
| | - Brian C VanderVen
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14850, USA
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29
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Aguilar-Ayala DA, Tilleman L, Van Nieuwerburgh F, Deforce D, Palomino JC, Vandamme P, Gonzalez-Y-Merchand JA, Martin A. The transcriptome of Mycobacterium tuberculosis in a lipid-rich dormancy model through RNAseq analysis. Sci Rep 2017; 7:17665. [PMID: 29247215 PMCID: PMC5732278 DOI: 10.1038/s41598-017-17751-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/29/2017] [Indexed: 12/23/2022] Open
Abstract
Tuberculosis (TB) is currently the number one killer among infectious diseases worldwide. Lipids are abundant molecules during the infectious cycle of Mycobacterium tuberculosis (Mtb) and studies better mimicking its actual metabolic state during pathogenesis are needed. Though most studies have focused on the mycobacterial lipid metabolism under standard culture conditions, little is known about the transcriptome of Mtb in a lipid environment. Here we determined the transcriptome of Mtb H37Rv in a lipid-rich environment (cholesterol and fatty acid) under aerobic and hypoxic conditions, using RNAseq. Lipids significantly induced the expression of 368 genes. A main core lipid response was observed involving efflux systems, iron caption and sulfur reduction. In co-expression with ncRNAs and other genes discussed below, may act coordinately to prepare the machinery conferring drug tolerance and increasing a persistent population. Our findings could be useful to tag relevant pathways for the development of new drugs, vaccines and new strategies to control TB.
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Affiliation(s)
- Diana A Aguilar-Ayala
- Laboratory of Microbiology, Faculty of Science, Ghent University, Gent, Belgium.
- Laboratory of Molecular Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico.
| | - Laurentijn Tilleman
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Gent, Belgium
| | - Filip Van Nieuwerburgh
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Gent, Belgium
| | - Dieter Deforce
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Gent, Belgium
| | | | - Peter Vandamme
- Laboratory of Microbiology, Faculty of Science, Ghent University, Gent, Belgium
| | - Jorge A Gonzalez-Y-Merchand
- Laboratory of Molecular Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Anandi Martin
- Laboratory of Microbiology, Faculty of Science, Ghent University, Gent, Belgium
- Pôle of Medical Microbiology, Institute of Experimental and Clinical Research, Université Catholique de, Louvain, Brussels, Belgium
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30
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Boot M, van Winden VJC, Sparrius M, van de Weerd R, Speer A, Ummels R, Rustad T, Sherman DR, Bitter W. Cell envelope stress in mycobacteria is regulated by the novel signal transduction ATPase IniR in response to trehalose. PLoS Genet 2017; 13:e1007131. [PMID: 29281637 PMCID: PMC5760070 DOI: 10.1371/journal.pgen.1007131] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 01/09/2018] [Accepted: 11/28/2017] [Indexed: 12/20/2022] Open
Abstract
The cell envelope of mycobacteria is a highly unique and complex structure that is functionally equivalent to that of Gram-negative bacteria to protect the bacterial cell. Defects in the integrity or assembly of this cell envelope must be sensed to allow the induction of stress response systems. The promoter that is specifically and most strongly induced upon exposure to ethambutol and isoniazid, first line drugs that affect cell envelope biogenesis, is the iniBAC promoter. In this study, we set out to identify the regulator of the iniBAC operon in Mycobacterium marinum using an unbiased transposon mutagenesis screen in a constitutively iniBAC-expressing mutant background. We obtained multiple mutants in the mce1 locus as well as mutants in an uncharacterized putative transcriptional regulator (MMAR_0612). This latter gene was shown to function as the iniBAC regulator, as overexpression resulted in constitutive iniBAC induction, whereas a knockout mutant was unable to respond to the presence of ethambutol and isoniazid. Experiments with the M. tuberculosis homologue (Rv0339c) showed identical results. RNAseq experiments showed that this regulatory gene was exclusively involved in the regulation of the iniBAC operon. We therefore propose to name this dedicated regulator iniBAC Regulator (IniR). IniR belongs to the family of signal transduction ATPases with numerous domains, including a putative sugar-binding domain. Upon testing different sugars, we identified trehalose as an activator and metabolic cue for iniBAC activation, which could also explain the effect of the mce1 mutations. In conclusion, cell envelope stress in mycobacteria is regulated by IniR in a cascade that includes trehalose.
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Affiliation(s)
- Maikel Boot
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
| | - Vincent J. C. van Winden
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
| | - Marion Sparrius
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
| | - Robert van de Weerd
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
| | - Alexander Speer
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
| | - Roy Ummels
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
| | - Tige Rustad
- Center for Infectious Disease, Seattle, Washington, United States of America
| | - David R. Sherman
- Center for Infectious Disease, Seattle, Washington, United States of America
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, the Netherlands
- Department of Molecular Microbiology, VU University, Amsterdam, the Netherlands
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31
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Isom GL, Davies NJ, Chong ZS, Bryant JA, Jamshad M, Sharif M, Cunningham AF, Knowles TJ, Chng SS, Cole JA, Henderson IR. MCE domain proteins: conserved inner membrane lipid-binding proteins required for outer membrane homeostasis. Sci Rep 2017; 7:8608. [PMID: 28819315 PMCID: PMC5561183 DOI: 10.1038/s41598-017-09111-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/20/2017] [Indexed: 01/12/2023] Open
Abstract
Bacterial proteins with MCE domains were first described as being important for Mammalian Cell Entry. More recent evidence suggests they are components of lipid ABC transporters. In Escherichia coli, the single-domain protein MlaD is known to be part of an inner membrane transporter that is important for maintenance of outer membrane lipid asymmetry. Here we describe two multi MCE domain-containing proteins in Escherichia coli, PqiB and YebT, the latter of which is an orthologue of MAM-7 that was previously reported to be an outer membrane protein. We show that all three MCE domain-containing proteins localise to the inner membrane. Bioinformatic analyses revealed that MCE domains are widely distributed across bacterial phyla but multi MCE domain-containing proteins evolved in Proteobacteria from single-domain proteins. Mutants defective in mlaD, pqiAB and yebST were shown to have distinct but partially overlapping phenotypes, but the primary functions of PqiB and YebT differ from MlaD. Complementing our previous findings that all three proteins bind phospholipids, results presented here indicate that multi-domain proteins evolved in Proteobacteria for specific functions in maintaining cell envelope homeostasis.
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Affiliation(s)
- Georgia L Isom
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Nathaniel J Davies
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Zhi-Soon Chong
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Jack A Bryant
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Mohammed Jamshad
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Maria Sharif
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Adam F Cunningham
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Timothy J Knowles
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Jeffrey A Cole
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ian R Henderson
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom.
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Abstract
All bacteria utilize pathways to export proteins from the cytoplasm to the bacterial cell envelope or extracellular space. Many exported proteins function in essential physiological processes or in virulence. Consequently, the responsible protein export pathways are commonly essential and/or are important for pathogenesis. The general Sec protein export pathway is conserved and essential in all bacteria, and it is responsible for most protein export. The energy for Sec export is provided by the SecA ATPase. Mycobacteria and some Gram-positive bacteria have two SecA paralogs: SecA1 and SecA2. SecA1 is essential and works with the canonical Sec pathway to perform the bulk of protein export. The nonessential SecA2 exports a smaller subset of proteins and is required for the virulence of pathogens such as Mycobacterium tuberculosis. In this article, we review our current understanding of the mechanism of the SecA1 and SecA2 export pathways and discuss some of their better-studied exported substrates. We focus on proteins with established functions in M. tuberculosis pathogenesis and proteins that suggest potential roles for SecA1 and SecA2 in M. tuberculosis dormancy.
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Nazarova EV, Montague CR, La T, Wilburn KM, Sukumar N, Lee W, Caldwell S, Russell DG, VanderVen BC. Rv3723/LucA coordinates fatty acid and cholesterol uptake in Mycobacterium tuberculosis. eLife 2017; 6:e26969. [PMID: 28708968 PMCID: PMC5487216 DOI: 10.7554/elife.26969] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 06/07/2017] [Indexed: 01/05/2023] Open
Abstract
Pathogenic bacteria have evolved highly specialized systems to extract essential nutrients from their hosts. Mycobacterium tuberculosis (Mtb) scavenges lipids (cholesterol and fatty acids) to maintain infections in mammals but mechanisms and proteins responsible for the import of fatty acids in Mtb were previously unknown. Here, we identify and determine that the previously uncharacterized protein Rv3723/LucA, functions to integrate cholesterol and fatty acid uptake in Mtb. Rv3723/LucA interacts with subunits of the Mce1 and Mce4 complexes to coordinate the activities of these nutrient transporters by maintaining their stability. We also demonstrate that Mce1 functions as a fatty acid transporter in Mtb and determine that facilitating cholesterol and fatty acid import via Rv3723/LucA is required for full bacterial virulence in vivo. These data establish that fatty acid and cholesterol assimilation are inexorably linked in Mtb and reveals a key function for Rv3723/LucA in in coordinating thetransport of both these substrates.
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Affiliation(s)
- Evgeniya V Nazarova
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Christine R Montague
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Thuy La
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Kaley M Wilburn
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Neelima Sukumar
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Wonsik Lee
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Shannon Caldwell
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - David G Russell
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
| | - Brian C VanderVen
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, United States
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34
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Ekiert DC, Bhabha G, Isom GL, Greenan G, Ovchinnikov S, Henderson IR, Cox JS, Vale RD. Architectures of Lipid Transport Systems for the Bacterial Outer Membrane. Cell 2017; 169:273-285.e17. [PMID: 28388411 PMCID: PMC5467742 DOI: 10.1016/j.cell.2017.03.019] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/07/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
Abstract
How phospholipids are trafficked between the bacterial inner and outer membranes through the hydrophilic space of the periplasm is not known. We report that members of the mammalian cell entry (MCE) protein family form hexameric assemblies with a central channel capable of mediating lipid transport. The E. coli MCE protein, MlaD, forms a ring associated with an ABC transporter complex in the inner membrane. A soluble lipid-binding protein, MlaC, ferries lipids between MlaD and an outer membrane protein complex. In contrast, EM structures of two other E. coli MCE proteins show that YebT forms an elongated tube consisting of seven stacked MCE rings, and PqiB adopts a syringe-like architecture. Both YebT and PqiB create channels of sufficient length to span the periplasmic space. This work reveals diverse architectures of highly conserved protein-based channels implicated in the transport of lipids between the membranes of bacteria and some eukaryotic organelles.
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Affiliation(s)
- Damian C Ekiert
- Department of Cellular and Molecular Pharmacology and the Howard Hughes Medical Institute, The University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94158, USA; Department of Microbiology and Immunology, The University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94158, USA.
| | - Gira Bhabha
- Department of Cellular and Molecular Pharmacology and the Howard Hughes Medical Institute, The University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94158, USA
| | - Georgia L Isom
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | - Garrett Greenan
- Department of Cellular and Molecular Pharmacology and the Howard Hughes Medical Institute, The University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94158, USA
| | - Sergey Ovchinnikov
- Institute for Protein Design, University of Washington, Seattle, WA 98195, USA
| | - Ian R Henderson
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | - Jeffery S Cox
- Department of Microbiology and Immunology, The University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94158, USA
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology and the Howard Hughes Medical Institute, The University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94158, USA
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35
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Queiroz A, Riley LW. Bacterial immunostat: Mycobacterium tuberculosis lipids and their role in the host immune response. Rev Soc Bras Med Trop 2017; 50:9-18. [DOI: 10.1590/0037-8682-0230-2016] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/22/2016] [Indexed: 11/22/2022] Open
Affiliation(s)
- Adriano Queiroz
- University of California, USA; Fundação Oswaldo Cruz, Brazil
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Aguilar-Ayala DA, Palomino JC, Vandamme P, Martin A, Gonzalez-Y-Merchand JA. "Genetic regulation of Mycobacterium tuberculosis in a lipid-rich environment". INFECTION GENETICS AND EVOLUTION 2016; 55:392-402. [PMID: 27771519 DOI: 10.1016/j.meegid.2016.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 10/15/2016] [Accepted: 10/18/2016] [Indexed: 01/19/2023]
Abstract
Tuberculosis (TB) remains as one of the leading causes of morbidity and mortality among infectious diseases worldwide. Although lipids (mainly fatty acids and cholesterol) have been reported to play an important role during active and latent infection of M. tuberculosis, there are other molecular aspects of bacterial response to those substrates that are not fully understood, involving gene regulation background. This review highlights recent insights on pathogen gene expression: regulation during its active growth, during survival in presence of lipids and under variable hostile host microenvironments. We also propose several application options of this knowledge that may contribute for improved TB control.
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Affiliation(s)
- Diana A Aguilar-Ayala
- Departamento de Microbiologia, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Prolongacion de Carpio y Plan de Ayala S/N, Mexico City, Mexico; Department of Biochemistry and Microbiology, Faculty of Sciences, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Juan Carlos Palomino
- Department of Biochemistry and Microbiology, Faculty of Sciences, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Peter Vandamme
- Department of Biochemistry and Microbiology, Faculty of Sciences, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Anandi Martin
- Department of Biochemistry and Microbiology, Faculty of Sciences, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium.
| | - Jorge A Gonzalez-Y-Merchand
- Departamento de Microbiologia, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Prolongacion de Carpio y Plan de Ayala S/N, Mexico City, Mexico; Red Multidisciplinaria de Investigación en Tuberculosis, Mexico.
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Transcriptional Profiling of Mycobacterium tuberculosis Exposed to In Vitro Lysosomal Stress. Infect Immun 2016; 84:2505-23. [PMID: 27324481 DOI: 10.1128/iai.00072-16] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 06/10/2016] [Indexed: 12/27/2022] Open
Abstract
Increasing experimental evidence supports the idea that Mycobacterium tuberculosis has evolved strategies to survive within lysosomes of activated macrophages. To further our knowledge of M. tuberculosis response to the hostile lysosomal environment, we profiled the global transcriptional activity of M. tuberculosis when exposed to the lysosomal soluble fraction (SF) prepared from activated macrophages. Transcriptome sequencing (RNA-seq) analysis was performed using various incubation conditions, ranging from noninhibitory to cidal based on the mycobacterial replication or killing profile. Under inhibitory conditions that led to the absence of apparent mycobacterial replication, M. tuberculosis expressed a unique transcriptome with modulation of genes involved in general stress response, metabolic reprogramming, respiration, oxidative stress, dormancy response, and virulence. The transcription pattern also indicates characteristic cell wall remodeling with the possible outcomes of increased infectivity, intrinsic resistance to antibiotics, and subversion of the host immune system. Among the lysosome-specific responses, we identified the glgE-mediated 1,4 α-glucan synthesis pathway and a defined group of VapBC toxin/anti-toxin systems, both of which represent toxicity mechanisms that potentially can be exploited for killing intracellular mycobacteria. A meta-analysis including previously reported transcriptomic studies in macrophage infection and in vitro stress models was conducted to identify overlapping and nonoverlapping pathways. Finally, the Tap efflux pump-encoding gene Rv1258c was selected for validation. An M. tuberculosis ΔRv1258c mutant was constructed and displayed increased susceptibility to killing by lysosomal SF and the antimicrobial peptide LL-37, as well as attenuated survival in primary murine macrophages and human macrophage cell line THP-1.
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Ndlandla FL, Ejoh V, Stoltz AC, Naicker B, Cromarty AD, van Wyngaardt S, Khati M, Rotherham LS, Lemmer Y, Niebuhr J, Baumeister CR, Al Dulayymi JR, Swai H, Baird MS, Verschoor JA. Standardization of natural mycolic acid antigen composition and production for use in biomarker antibody detection to diagnose active tuberculosis. J Immunol Methods 2016; 435:50-9. [PMID: 27247168 DOI: 10.1016/j.jim.2016.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/21/2016] [Accepted: 05/24/2016] [Indexed: 10/21/2022]
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, is characterized by the abundance of species specific, antigenic cell wall lipids called mycolic acids. These wax-like molecules all share an identical, amphiphilic mycolic motif, but have different functional groups in a long hydrophobic hydrocarbon mero-chain that divide them into three main classes: alpha-, keto- and methoxy-mycolic acids. Whereas alpha-mycolic acids constitutively maintain an abundance of around 50%, the ratio of methoxy- to keto-mycolic acid types may vary depending on, among other things, the growth stage of M. tuberculosis. In human patients, antibodies to mycolic acids have shown potential as diagnostic serum biomarkers for active TB. Variations in mycolic acid composition affect the antigenic properties and can potentially compromise the precision of detection of anti-mycolic acids antibodies in patient sera to natural mixtures. We demonstrate this here with combinations of synthetic mycolic acid antigens, tested against TB patient and control sera. Combinations of methoxy- and α-mycolic acids are more antigenic than combinations of keto- and α-mycolic acids, showing the former to give a more sensitive test for TB biomarker antibodies. Natural mixtures of mycolic acids isolated from mature cultures of M. tuberculosis H37Rv give the same sensitivity as that with synthetic methoxy- and α-mycolic acids in combination, in a surface plasmon resonance inhibition biosensor test. To ensure that the antigenic activity of isolates of natural mycolic acids is reproducible, we cultured M. tuberculosis H37Rv on Middlebrook 7H10 solid agar plates to stationary growth phase in a standardized, optimal way. The proportions of mycolic acid classes in various batches of the isolates prepared from these cultures were compared to a commercially available natural mycolic acid isolate. LC-MS/MS and NMR data for quantitation of mycolic acids class compositions show that the variation in batches is small, suggesting that the quality of the results for anti-mycolic acid antibody detection in the TB patients should not be affected by different batches of natural mycolic acid antigens if prepared in a standard way.
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Affiliation(s)
- F L Ndlandla
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa; Department of Biochemistry, University of Pretoria, South Africa
| | - V Ejoh
- Department of Biochemistry, University of Pretoria, South Africa
| | - A C Stoltz
- Division of Infectious Diseases, Faculty of Health Sciences, University of Pretoria, South Africa
| | - B Naicker
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa; Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - A D Cromarty
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - S van Wyngaardt
- Department of Biochemistry, University of Pretoria, South Africa
| | - M Khati
- Biosciences, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - L S Rotherham
- Biosciences, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Y Lemmer
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - J Niebuhr
- Department of Biochemistry, University of Pretoria, South Africa
| | - C R Baumeister
- Department of Biochemistry, University of Pretoria, South Africa
| | | | - H Swai
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - M S Baird
- School of Chemistry, Bangor University, Wales, UK
| | - J A Verschoor
- Department of Biochemistry, University of Pretoria, South Africa
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Zandhaghighi M, Ghazvini K, Meshkat Z, Rezaee SA, Derakhshan M, Soleimanpour S, Hadizadeh F. Screening of the antimycobacterial activity of novel lipophilic agents by the modified broth based method. J Clin Tuberc Other Mycobact Dis 2016; 3:1-5. [PMID: 31723679 PMCID: PMC6850257 DOI: 10.1016/j.jctube.2016.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 12/29/2015] [Accepted: 01/25/2016] [Indexed: 10/29/2022] Open
Abstract
Most of the introduced susceptibility methods of Mycobacterium tuberculosis have some disadvantages for screening. Therefore, the selection of susceptibility assay for evaluating candidate agents must be determined case by case. In this study, we evaluated the validity of a modified broth dilution-based assay in comparison to the gold standard proportional method for microbial sensitivity test of new lipophilic compounds candidate as antitubercular agents. The in-vitro susceptibilities of 114 M. tuberculosis strains were separately tested against isoniazid and two lipophilic antitubercular agents (derivative of dihydropyridines) by employing the standard proportional method and a modified broth dilution-based assay. The results for isoniazid testing showed 100% concordance for sensitivity, specificity and reproducibility. In the case of microbial sensitivity test of lipophilic compounds, comparison of the results obtained from these two methods indicates a significant superiority of the modified method over the standard method. Considering the other advantages of this modified method, we concluded that this modified broth dilution-based assay could be utilized effectively for the susceptibility testing of new lipophilic compounds candidate as antitubercular agents.
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Affiliation(s)
- Mehdi Zandhaghighi
- Antimicrobial Resistance Research Center & Department of Medical Bacteriology and Virology, Bu-Ali Research Institute & Ghaem University Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Kiarash Ghazvini
- Antimicrobial Resistance Research Center & Department of Medical Bacteriology and Virology, Bu-Ali Research Institute & Ghaem University Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zahra Meshkat
- Antimicrobial Resistance Research Center & Department of Medical Bacteriology and Virology, Bu-Ali Research Institute & Ghaem University Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Seyed Abdolrahim Rezaee
- Antimicrobial Resistance Research Center & Department of Medical Bacteriology and Virology, Bu-Ali Research Institute & Ghaem University Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad Derakhshan
- Antimicrobial Resistance Research Center & Department of Medical Bacteriology and Virology, Bu-Ali Research Institute & Ghaem University Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Saman Soleimanpour
- Antimicrobial Resistance Research Center & Department of Medical Bacteriology and Virology, Bu-Ali Research Institute & Ghaem University Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Farzin Hadizadeh
- Biotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
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Perkowski EF, Miller BK, McCann JR, Sullivan JT, Malik S, Allen IC, Godfrey V, Hayden JD, Braunstein M. An orphaned Mce-associated membrane protein of Mycobacterium tuberculosis is a virulence factor that stabilizes Mce transporters. Mol Microbiol 2016; 100:90-107. [PMID: 26712165 DOI: 10.1111/mmi.13303] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2015] [Indexed: 12/17/2022]
Abstract
Mycobacterium tuberculosis proteins that are exported out of the bacterial cytoplasm are ideally positioned to be virulence factors; however, the functions of individual exported proteins remain largely unknown. Previous studies identified Rv0199 as an exported membrane protein of unknown function. Here, we characterized the role of Rv0199 in M. tuberculosis virulence using an aerosol model of murine infection. Rv0199 appears to be a member of a Mce-associated membrane (Mam) protein family leading us to rename it OmamA, for orphaned Mam protein A. Consistent with a role in Mce transport, we showed OmamA is required for cholesterol import, which is a Mce4-dependent process. We further demonstrated a function for OmamA in stabilizing protein components of the Mce1 transporter complex. These results indicate a function of OmamA in multiple Mce transporters and one that may be analogous to the role of VirB8 in stabilizing Type IV secretion systems, as structural similarities between Mam proteins and VirB8 proteins are predicted by the Phyre 2 program. In this study, we provide functional information about OmamA and shed light on the function of Mam family proteins in Mce transporters.
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Affiliation(s)
| | - Brittany K Miller
- Department of Microbiology and Immunology, University of North Carolina
| | - Jessica R McCann
- Department of Microbiology and Immunology, University of North Carolina
| | | | - Seidu Malik
- Department of Microbiology and Immunology, University of North Carolina
| | - Irving Coy Allen
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine
| | - Virginia Godfrey
- Department of Pathology and Laboratory Medicine, University of North Carolina
| | - Jennifer D Hayden
- Department of Microbiology and Immunology, University of North Carolina
| | - Miriam Braunstein
- Department of Microbiology and Immunology, University of North Carolina
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41
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Queiroz A, Medina-Cleghorn D, Marjanovic O, Nomura DK, Riley LW. Comparative metabolic profiling of mce1 operon mutant vs wild-type Mycobacterium tuberculosis strains. Pathog Dis 2015; 73:ftv066. [PMID: 26319139 DOI: 10.1093/femspd/ftv066] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2015] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium tuberculosis disrupted in a 13-gene operon (mce1) accumulates free mycolic acids (FM) in its cell wall and causes accelerated death in mice. Here, to more comprehensively analyze differences in their cell wall lipid composition, we used an untargeted metabolomics approach to compare the lipid profiles of wild-type and mce1 operon mutant strains. By liquid chromatography-mass spectrometry, we identified >400 distinct lipids significantly altered in the mce1 mutant compared to wild type. These lipids included decreased levels of saccharolipids and glycerophospholipids, and increased levels of alpha-, methoxy- and keto mycolic acids (MA), and hydroxyphthioceranic acid. The mutant showed reduced expression of mmpL8, mmpL10, stf0, pks2 and papA2 genes involved in transport and metabolism of lipids recognized to induce proinflammatory response; these lipids were found to be decreased in the mutant. In contrast, the transcripts of mmpL3, fasI, kasA, kasB, acpM and RV3451 involved in MA transport and metabolism increased; MA inhibits inflammatory response in macrophages. Since the mce1 operon is known to be regulated in intracellular M. tuberculosis, we speculate that the differences we observed in cell wall lipid metabolism and composition may affect host response to M. tuberculosis infection and determine the clinical outcome of such an infection.
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Affiliation(s)
- Adriano Queiroz
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, CA 94720, USA
| | - Daniel Medina-Cleghorn
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA
| | - Olivera Marjanovic
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, CA 94720, USA
| | - Daniel K Nomura
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA
| | - Lee W Riley
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, CA 94720, USA
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42
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Feltcher ME, Gunawardena HP, Zulauf KE, Malik S, Griffin JE, Sassetti CM, Chen X, Braunstein M. Label-free Quantitative Proteomics Reveals a Role for the Mycobacterium tuberculosis SecA2 Pathway in Exporting Solute Binding Proteins and Mce Transporters to the Cell Wall. Mol Cell Proteomics 2015; 14:1501-16. [PMID: 25813378 DOI: 10.1074/mcp.m114.044685] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Indexed: 01/18/2023] Open
Abstract
Mycobacterium tuberculosis is an example of a bacterial pathogen with a specialized SecA2-dependent protein export system that contributes to its virulence. Our understanding of the mechanistic basis of SecA2-dependent export and the role(s) of the SecA2 pathway in M. tuberculosis pathogenesis has been hindered by our limited knowledge of the proteins exported by the pathway. Here, we set out to identify M. tuberculosis proteins that use the SecA2 pathway for their export from the bacterial cytoplasm to the cell wall. Using label-free quantitative proteomics involving spectral counting, we compared the cell wall and cytoplasmic proteomes of wild type M. tuberculosis to that of a ΔsecA2 mutant. This work revealed a role for the M. tuberculosis SecA2 pathway in the cell wall localization of solute binding proteins that work with ABC transporters to import solutes. Another discovery was a profound effect of SecA2 on the cell wall localization of the Mce1 and Mce4 lipid transporters, which contribute to M. tuberculosis virulence. In addition to the effects on solute binding proteins and Mce transporter export, our label-free quantitative analysis revealed an unexpected relationship between SecA2 and the hypoxia-induced DosR regulon, which is associated with M. tuberculosis latency. Nearly half of the transcriptionally controlled DosR regulon of cytoplasmic proteins were detected at higher levels in the ΔsecA2 mutant versus wild type M. tuberculosis. By increasing the list of M. tuberculosis proteins known to be affected by the SecA2 pathway, this study expands our appreciation of the types of proteins exported by this pathway and guides our understanding of the mechanism of SecA2-dependent protein export in mycobacteria. At the same time, the newly identified SecA2-dependent proteins are helpful for understanding the significance of this pathway to M. tuberculosis virulence and physiology.
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Affiliation(s)
| | - Harsha P Gunawardena
- §Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, North Carolina, 27599
| | | | - Seidu Malik
- From the ‡Department of Microbiology and Immunology
| | - Jennifer E Griffin
- ¶Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Christopher M Sassetti
- ¶Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655; ‖Howard Hughes Medical Institute, Chevy Chase, Maryland, 20815
| | - Xian Chen
- §Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, North Carolina, 27599;
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Li W, Fan X, Long Q, Xie L, Xie J. Mycobacterium tuberculosis effectors involved in host-pathogen interaction revealed by a multiple scales integrative pipeline. INFECTION GENETICS AND EVOLUTION 2015; 32:1-11. [PMID: 25709069 DOI: 10.1016/j.meegid.2015.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 02/02/2015] [Accepted: 02/14/2015] [Indexed: 01/04/2023]
Abstract
BACKGROUND Mycobacterium tuberculosis (Mtb) has evolved multiple strategies to counter host immunity. Proteins are one important player in the host-pathogen interaction. A comprehensive list of such proteins will benefit our understanding of pathogenesis of Mtb. METHODS A genome-scale dataset was created from different sources of published data: global gene expression studies in disease models; genome-wide insertional mutagenesis defining gene essentiality under different conditions; genes lost in clinical isolates; subcellular localization analysis and non-homology analysis. Using data mining and meta-analysis, expressed proteins critical for intracellular survival of Mtb are first identified, followed by subcellular localization analysis, finally filtering a series of subtractive channel of analysis to find out promising drug target candidates. RESULTS The analysis found 54 potential candidates essential for the intracellular survival of the pathogen and non-homologous to host or gut flora, and might be promising drug targets. CONCLUSION Based on our meta-analysis and bioinformatics analysis, 54 hits were found from Mtb around 4000 open reading frames. These hits can be good candidates for further experimental investigation.
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Affiliation(s)
- Wu Li
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Xiangyu Fan
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China; School of Biological Science and Technology, University of Jinan, Shandong 250022, China
| | - Quanxin Long
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China; The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases of the Ministry of Education, Chongqing Medical University, 1 Medical Road, Yuzhong District, Chongqing 400016, China
| | - Longxiang Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Jianping Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China.
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Shanmuganathan R, Subramaniam ID. Clinical manifestation and risk factors of tuberculosis infection in Malaysia: case study of a community clinic. Glob J Health Sci 2015; 7:110-20. [PMID: 25946947 PMCID: PMC4802090 DOI: 10.5539/gjhs.v7n4p110] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 12/01/2014] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION The main aim of this study was to describe the clinical manifestation of tuberculosis infection cases in Malaysia and to determine the individual risk factors for their occurrence. METHODOLOGY The study adopted a quantitative research approach with use of descriptive statistical approach. The study setting was a community clinic which treats walk in patients who are mainly living and working in the surrounding areas. The study was conducted for a period of one year. All tuberculosis patients who sought treatment in the clinic during the time were included in this study. The total number of cases was 40. Data was collected from the medical records of the tuberculosis patients. The risk factors selected for investigation were demographic characteristics of age and sex, personal habits such as smoking, drug use and alcohol and presence of diseases such as human immunodeficiency virus positive (HIV+), diabetes mellitus, cancer, cyanotic heart disease, renal failure and steroid use. RESULTS Patients in the age group ranging from 41 to 50 years had the highest incidence of the infection. Smoking appears to be the most important risk factor for contracting followed by drug abuse, HIV+ infection and diabetes mellitus. CONCLUSIONS People with diseases such as diabetes mellitus and HIV that are high risk factors for TB should be screened for TB so that early detection and intervention is possible. Educational programs should be carried out to create awareness among the at risk groups.
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Thirunavukkarasu S, de Silva K, Plain KM, J Whittington R. Role of host- and pathogen-associated lipids in directing the immune response in mycobacterial infections, with emphasis on Mycobacterium avium subsp. paratuberculosis. Crit Rev Microbiol 2014; 42:262-75. [PMID: 25163812 DOI: 10.3109/1040841x.2014.932327] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mycobacteria have a complex cell wall with a high lipid content that confers unique advantages for bacterial survival in the hostile host environment, leading to long-term infection. There is a wealth of evidence suggesting the role cell wall-associated lipid antigens play at the host-pathogen interface by contributing to bacterial virulence. One pathway that pathogenic mycobacteria use to subvert host immune pathways to their advantage is host cholesterol/lipid homeostasis. This review focuses on the possible role of pathogen- and host-associated lipids in the survival and persistence of pathogenic mycobacteria with emphasis on Mycobacterium avium subsp. paratuberculosis. We draw upon literature in diverse areas of infectious and metabolic diseases and explain a mechanism by which mycobacterial-induced changes in the host cellular energy state could account for phenomena that are a hallmark of chronic mycobacterial diseases.
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Affiliation(s)
| | - Kumudika de Silva
- a Faculty of Veterinary Science , University of Sydney , Camden , Australia
| | - Karren M Plain
- a Faculty of Veterinary Science , University of Sydney , Camden , Australia
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Forrellad MA, McNeil M, Santangelo MDLP, Blanco FC, García E, Klepp LI, Huff J, Niederweis M, Jackson M, Bigi F. Role of the Mce1 transporter in the lipid homeostasis of Mycobacterium tuberculosis. Tuberculosis (Edinb) 2014; 94:170-7. [PMID: 24440549 PMCID: PMC3951760 DOI: 10.1016/j.tube.2013.12.005] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 12/15/2013] [Accepted: 12/18/2013] [Indexed: 12/19/2022]
Abstract
Tuberculosis is one of the leading causes of mortality throughout the world. Mycobacterium tuberculosis, the causative agent of human tuberculosis, has developed several strategies involving proteins and other compounds known collectively as virulence factors to subvert human host defences and invade the human host. The Mce proteins are among these virulence-related proteins and are encoded by the mce1, mce2, mce3 and mce4 operons in the genome of M. tuberculosis. It has been proposed that these operons encode ABC-like lipid transporters; however, the nature of their substrates has only been revealed in the case of the Mce4 proteins. Here we found that the knockout of the mce1 operon alters the lipid profile of M. tuberculosis H37Rv and the uptake of palmitic acid. Thin layer chromatography and liquid chromatography-mass spectrometry analysis showed that the mce1 mutant accumulates more mycolic acids than the wild type and complemented strains. Interestingly, this accumulation of mycolic acid is exacerbated when bacteria are cultured in the presence of palmitic acid or arachidonic acid. These results suggest that the mce1 operon may serve as a mycolic acid re-importer.
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Affiliation(s)
- Marina Andrea Forrellad
- Instituto de Biotecnología, CICVyA - INTA, N. Repetto and De los Reseros, Hurlingham 1686, Argentina
| | - Michael McNeil
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | | | - Federico Carlos Blanco
- Instituto de Biotecnología, CICVyA - INTA, N. Repetto and De los Reseros, Hurlingham 1686, Argentina
| | - Elizabeth García
- Instituto de Biotecnología, CICVyA - INTA, N. Repetto and De los Reseros, Hurlingham 1686, Argentina
| | - Laura Inés Klepp
- Instituto de Biotecnología, CICVyA - INTA, N. Repetto and De los Reseros, Hurlingham 1686, Argentina
| | - Jason Huff
- Department of Microbiology, University of Alabama at Birmingham, 609 Bevill Biomedical Research Building, 845 19th Street South, Birmingham, AL 35294, USA
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, 609 Bevill Biomedical Research Building, 845 19th Street South, Birmingham, AL 35294, USA
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Fabiana Bigi
- Instituto de Biotecnología, CICVyA - INTA, N. Repetto and De los Reseros, Hurlingham 1686, Argentina.
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47
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Sequeira PC, Senaratne RH, Riley LW. Inhibition of toll-like receptor 2 (TLR-2)-mediated response in human alveolar epithelial cells by mycolic acids and Mycobacterium tuberculosis mce1 operon mutant. Pathog Dis 2013; 70:132-40. [PMID: 24190334 DOI: 10.1111/2049-632x.12110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/16/2013] [Accepted: 10/23/2013] [Indexed: 01/12/2023] Open
Abstract
In human lungs, the earliest encounter of Mycobacterium tuberculosis, the agent of tuberculosis, involves alveolar epithelial cells. Droplets expectorated by a patient with tuberculosis are likely to contain a mixed population of M. tuberculosis cells in different physiologic and metabolic states from the lung lesions of the patient. Here, we compared the chemokine expression patterns of human epithelial cell line A549 and RAW 264.7 macrophage cells infected with wild-type M. tuberculosis H37Rv against patterns induced by a mutant that accumulates free mycolic acids in its cell wall (Δmce1). We also examined the effect of free mycolic acids on toll-like receptor-2 (TLR-2). Wild-type M. tuberculosis induced significantly higher levels of IL-8, MCP-1, RANTES, and IP-10 in both cell types than did Δmce. Free mycolic acids reduced the ability of the mammalian cells to respond to a TLR-2 agonist in a dose-dependent manner. These observations suggest that differences in mycolic acid abundance in the M. tuberculosis cell wall can affect TLR-2-mediated pro-inflammatory response in both epithelial and macrophage cells. The final fate of a new infection may be ultimately determined by the proportion of M. tuberculosis cells expressing free mycolates in the infecting inoculum population.
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