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Edvardsen PKT, Askarian F, Zurich R, Nizet V, Vaaje-Kolstad G. Exploring roles of the chitinase ChiC in modulating Pseudomonas aeruginosa virulence phenotypes. Microbiol Spectr 2024; 12:e0054624. [PMID: 38819151 PMCID: PMC11218509 DOI: 10.1128/spectrum.00546-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 04/23/2024] [Indexed: 06/01/2024] Open
Abstract
Chitinases are ubiquitous enzymes involved in biomass degradation and chitin turnover in nature. Pseudomonas aeruginosa (PA), an opportunistic human pathogen, expresses ChiC, a secreted glycoside hydrolase 18 family chitinase. Despite speculation about ChiC's role in PA disease pathogenesis, there is scant evidence supporting this hypothesis. Since PA cannot catabolize chitin, we investigated the potential function(s) of ChiC in PA pathophysiology. Our findings show that ChiC exhibits activity against both insoluble (α- and β-chitin) and soluble chitooligosaccharides. Enzyme kinetics toward (GlcNAc)4 revealed a kcat of 6.50 s-1 and a KM of 1.38 mM, the latter remarkably high for a canonical chitinase. In our label-free proteomics investigation, ChiC was among the most abundant proteins in the Pel biofilm, suggesting a potential contribution to PA biofilm formation. Using an intratracheal challenge model of PA pneumonia, the chiC::ISphoA/hah transposon insertion mutant paradoxically showed slightly increased virulence compared to the wild-type parent strain. Our results indicate that ChiC is a genuine chitinase that contributes to a PA pathoadaptive pathway.IMPORTANCEIn addition to performing chitin degradation, chitinases from the glycoside hydrolase 18 family have been found to play important roles during pathogenic bacterial infection. Pseudomonas aeruginosa is an opportunistic pathogen capable of causing pneumonia in immunocompromised individuals. Despite not being able to grow on chitin, the bacterium produces a chitinase (ChiC) with hitherto unknown function. This study describes an in-depth characterization of ChiC, focusing on its potential contribution to the bacterium's disease-causing ability. We demonstrate that ChiC can degrade both polymeric chitin and chitooligosaccharides, and proteomic analysis of Pseudomonas aeruginosa biofilm revealed an abundance of ChiC, hinting at a potential role in biofilm formation. Surprisingly, a mutant strain incapable of ChiC production showed higher virulence than the wild-type strain. While ChiC appears to be a genuine chitinase, further investigation is required to fully elucidate its contribution to Pseudomonas aeruginosa virulence, an important task given the evident health risk posed by this bacterium.
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Affiliation(s)
| | - Fatemeh Askarian
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California, USA
| | - Raymond Zurich
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California, USA
| | - Victor Nizet
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, California, USA
| | - Gustav Vaaje-Kolstad
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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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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Lee D, Kim DH, Seo H, Choi S, Kim BJ. Phylogenetic distribution of malonate semialdehyde decarboxylase (MSAD) genes among strains within the genus Mycobacterium: evidence of MSAD gene loss in the evolution of pathogenic mycobacteria. Front Microbiol 2023; 14:1275616. [PMID: 37901833 PMCID: PMC10606566 DOI: 10.3389/fmicb.2023.1275616] [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: 08/10/2023] [Accepted: 09/29/2023] [Indexed: 10/31/2023] Open
Abstract
Despite the great diversity of malonate semialdehyde decarboxylases (MSADs), one of five subgroups of the tautomerase superfamily (TSF) found throughout the biosphere, their distribution among strains within the genus Mycobacterium remains unknown. In this study, we sought to investigate the phylogenetic distribution of MSAD genes of mycobacterial species via genome analysis of 192 different reference Mycobacterium species or subspecies retrieved from NCBI databases. We found that in a total of 87 of 192 strains (45.3%), MSAD-1 and MSAD-2 were distributed in an exclusive manner among Mycobacterium species except for 12 strains, including Mycobacterium chelonae members, with both in their genome. Of note, Mycobacterium strains better adapted to the host and of high virulence potential, such as the Mycobacterium tuberculosis complex, Mycobacterium leprae, Mycobacterium marinum, Mycobacterium ulcerans, and Mycobacterium avium subsp. paratuberculosis, had no orthologs of MSAD in their genome, suggesting MSAD loss during species differentiation in pathogenic slow-growing Mycobacterium. To investigate the MSAD distribution among strains of M. avium subspecies, the genome sequences of a total of 255 reference strains from the four subspecies of M. avium (43 of subspecies avium, 162 of subspecies hominissuis, 49 of subspecies paratuberculosis, and 1 of subspecies silvaticum) were further analyzed. We found that only 121 of 255 strains (47.4%) had MSADs in their genome, with none of the 49 M. avium subsp. paratuberculosis strains having MSAD genes. Even in 13 of 121 M. avium strains with the MSAD-1 gene in their genome, deletion mutations in the 98th codon causing premature termination of MSAD were found, further highlighting the occurrence of MSAD pseudogenization during species or subspecies differentiation of M. avium. In conclusion, our data indicated that there are two distinct types of MSADs, MSAD-1 and MSAD-2, among strains in the Mycobacterium genus, but more than half of the strains, including pathogenic mycobacteria, M. tuberculosis and M. leprae, have no orthologs in their genome, suggesting MSAD loss during host adaptation of pathogenic mycobacteria. In the future, the role of two distinct MSADs, MSAD-1 and MSAD-2, in mycobacterial pathogenesis or evolution should be investigated.
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Affiliation(s)
- Duhyung Lee
- Department of Microbiology and Immunology, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Cancer Research Institute, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Dong Hyun Kim
- Department of Microbiology and Immunology, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Hyejun Seo
- Department of Microbiology and Immunology, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Cancer Research Institute, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Seoul National University Medical Research Center, Seoul, Republic of Korea
| | - Seaone Choi
- Department of Microbiology and Immunology, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Brain Korea 21 FOUR Biomedical Science Project, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Bum-Joon Kim
- Department of Microbiology and Immunology, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Cancer Research Institute, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Seoul National University Medical Research Center, Seoul, Republic of Korea
- Brain Korea 21 FOUR Biomedical Science Project, Seoul National University College of Medicine, Seoul, Republic of Korea
- Liver Research Institute, College of Medicine, Seoul National University, Seoul, Republic of Korea
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4
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Baena A, Cabarcas F, Ocampo JC, Barrera LF, Alzate JF. Large genomic deletions delineate Mycobacterium tuberculosis L4 sublineages in South American countries. PLoS One 2023; 18:e0285417. [PMID: 37205685 PMCID: PMC10198500 DOI: 10.1371/journal.pone.0285417] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 04/24/2023] [Indexed: 05/21/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb) is still one of the primary pathogens of humans causing tuberculosis (TB) disease. Mtb embraces nine well-defined phylogenetic lineages with biological and geographical disparities. The lineage L4 is the most globally widespread of all lineages and was introduced to America with European colonization. Taking advantage of many genome projects available in public repositories, we undertake an evolutionary and comparative genomic analysis of 522 L4 Latin American Mtb genomes. Initially, we performed careful quality control of public read datasets and applied several thresholds to filter out low-quality data. Using a genome de novo assembly strategy and phylogenomic methods, we spotted novel south American clades that have not been revealed yet. Additionally, we describe genomic deletion profiles of these strains from an evolutionary perspective and report Mycobacterium tuberculosis L4 sublineages signature-like gene deletions, some of the novel. One is a specific deletion of 6.5 kbp that is only present in sublineage 4.1.2.1. This deletion affects a complex group of 10 genes with putative products annotated, among others, as a lipoprotein, transmembrane protein, and toxin/antitoxin system proteins. The second novel deletion spans for 4.9 kbp and specific of a particular clade of the 4.8 sublineage and affects 7 genes. The last novel deletion affects 4 genes, extends for 4.8 kbp., and is specific to some strains within the 4.1.2.1 sublineage that are present in Colombia, Peru and Brasil.
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Affiliation(s)
- Andres Baena
- Grupo de Inmunología Celular e Inmunogenética (GICIG), Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
- Sede de Investigación Universitaria-SIU, Universidad de Antioquia, Medellín, Colombia
| | - Felipe Cabarcas
- Centro Nacional de Secuenciación Genómica—CNSG, Universidad de Antioquia, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | - Juan C. Ocampo
- Grupo de Inmunología Celular e Inmunogenética (GICIG), Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
- Sede de Investigación Universitaria-SIU, Universidad de Antioquia, Medellín, Colombia
| | - Luis F. Barrera
- Grupo de Inmunología Celular e Inmunogenética (GICIG), Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
- Sede de Investigación Universitaria-SIU, Universidad de Antioquia, Medellín, Colombia
- Instituto de Investigaciones médicas, Universidad de Antioquia, Medellín, Colombia
| | - Juan F. Alzate
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
- Sede de Investigación Universitaria-SIU, Universidad de Antioquia, Medellín, Colombia
- Centro Nacional de Secuenciación Genómica—CNSG, Universidad de Antioquia, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
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Yokobori N, López B, Ritacco V. The host-pathogen-environment triad: Lessons learned through the study of the multidrug-resistant Mycobacterium tuberculosis M strain. Tuberculosis (Edinb) 2022; 134:102200. [PMID: 35339874 DOI: 10.1016/j.tube.2022.102200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/13/2022] [Accepted: 03/18/2022] [Indexed: 10/18/2022]
Abstract
Multidrug-resistant tuberculosis is one of the major obstacles that face the tuberculosis eradication efforts. Drug-resistant Mycobacterium tuberculosis clones were initially disregarded as a public health threat, because they were assumed to have paid a high fitness cost in exchange of resistance acquisition. However, some genotypes manage to overcome the impact of drug-resistance conferring mutations, retain transmissibility and cause large outbreaks. In Argentina, the HIV-AIDS epidemics fuelled the expansion of the so-called M strain in the early 1990s, which is responsible for the largest recorded multidrug-resistant tuberculosis cluster of Latin America. The aim of this work is to review the knowledge gathered after nearly three decades of multidisciplinary research on epidemiological, microbiological and immunological aspects of this highly successful strain. Collectively, our results indicate that the successful transmission of the M strain could be ascribed to its unaltered virulence, low Th1/Th17 response, a low fitness cost imposed by the resistance conferring mutations and a high resistance to host-related stress. In the early 2000s, the incident cases due to the M strain steadily declined and stabilized in the latest years. Improvements in the management, diagnosis and treatment of multidrug-resistant tuberculosis along with societal factors such as the low domestic and international mobility of the patients affected by this strain probably contributed to the outbreak containment. This stresses the importance of sustaining the public health interventions to avoid the resurgence of this conspicuous multidrug-resistant strain.
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Affiliation(s)
- Noemí Yokobori
- Servicio de Micobacterias, Instituto Nacional de Enfermedades Infecciosas, ANLIS "Dr. C. G. Malbrán", Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.
| | - Beatriz López
- Departamento de Bacteriología, Instituto Nacional de Enfermedades Infecciosas, ANLIS "Dr. C. G. Malbrán", Buenos Aires, Argentina.
| | - Viviana Ritacco
- Servicio de Micobacterias, Instituto Nacional de Enfermedades Infecciosas, ANLIS "Dr. C. G. Malbrán", Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.
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Abstract
The current TB treatment regimen involves a combination of drugs administered for an extended duration that could last for 6 months to 2 years. This could lead to noncompliance and the emergence of newer drug resistance strains. The worldwide increase in the frequency of multidrug-resistant and extensively drug-resistant cases of tuberculosis is mainly due to therapeutic noncompliance associated with a lengthy treatment regimen. Depending on the drug susceptibility profile, the treatment duration can extend from 6 months to 2 years. This protracted regimen is attributed to a supposedly nonreplicating and metabolically inert subset of the Mycobacterium tuberculosis population, called “persisters.” The mechanism underlying stochastic generation and enrichment of persisters is not fully known. We have previously reported that the utilization of host cholesterol is essential for mycobacterial persistence. In this study, we have demonstrated that cholesterol-induced activation of a RNase toxin (VapC12) inhibits translation by targeting proT tRNA in M. tuberculosis. This results in cholesterol-specific growth modulation that increases the frequency of generation of the persisters in a heterogeneous M. tuberculosis population. Also, a null mutant strain of this toxin (ΔvapC12) demonstrated an enhanced growth phenotype in a guinea pig model of M. tuberculosis infection, depicting its role in disease persistence. Thus, we have identified a novel strategy through which cholesterol-specific activation of a toxin-antitoxin module in M. tuberculosis enhances persister formation during infection. The current findings provide an opportunity to target persisters, a new paradigm facilitating tuberculosis drug development. IMPORTANCE The current TB treatment regimen involves a combination of drugs administered for an extended duration that could last for 6 months to 2 years. This could lead to noncompliance and the emergence of newer drug resistance strains. It is widely perceived that the major culprits are the so-called nonreplicating and metabolically inactive “persister” bacteria. The importance of cholesterol utilization during the persistence stage of M. tuberculosis infection and its potential role in the generation of persisters is very intriguing. We explored the mechanism involved in the cholesterol-mediated generation of persisters in mycobacteria. In this study, we have identified a toxin-antitoxin (TA) system essential for the generation of persisters during M. tuberculosis infection. This study verified that M. tuberculosis strain devoid of the VapBC12 TA system failed to persist and showed a hypervirulent phenotype in a guinea pig infection model. Our studies indicate that the M. tuberculosis VapBC12 TA system acts as a molecular switch regulating persister generation during infection. VapBC12 TA system as a drug target offers opportunities to develop shorter and more effective treatment regimens against tuberculosis.
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7
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Gallant J, Mouton J, Ummels R, Ten Hagen-Jongman C, Kriel N, Pain A, Warren RM, Bitter W, Heunis T, Sampson SL. Identification of gene fusion events in Mycobacterium tuberculosis that encode chimeric proteins. NAR Genom Bioinform 2020; 2:lqaa033. [PMID: 33575588 PMCID: PMC7671302 DOI: 10.1093/nargab/lqaa033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/16/2020] [Accepted: 05/05/2020] [Indexed: 02/07/2023] Open
Abstract
Mycobacterium tuberculosis is a facultative intracellular pathogen responsible for causing tuberculosis. The harsh environment in which M. tuberculosis survives requires this pathogen to continuously adapt in order to maintain an evolutionary advantage. However, the apparent absence of horizontal gene transfer in M. tuberculosis imposes restrictions in the ways by which evolution can occur. Large-scale changes in the genome can be introduced through genome reduction, recombination events and structural variation. Here, we identify a functional chimeric protein in the ppe38-71 locus, the absence of which is known to have an impact on protein secretion and virulence. To examine whether this approach was used more often by this pathogen, we further develop software that detects potential gene fusion events from multigene deletions using whole genome sequencing data. With this software we could identify a number of other putative gene fusion events within the genomes of M. tuberculosis isolates. We were able to demonstrate the expression of one of these gene fusions at the protein level using mass spectrometry. Therefore, gene fusions may provide an additional means of evolution for M. tuberculosis in its natural environment whereby novel chimeric proteins and functions can arise.
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Affiliation(s)
- James Gallant
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Science, Faculty of Medicine and Health Science, Stellenbosch University, Tygerberg, Cape Town 7505, South Africa.,Section of Molecular Microbiology, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands
| | - Jomien Mouton
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Science, Faculty of Medicine and Health Science, Stellenbosch University, Tygerberg, Cape Town 7505, South Africa
| | - Roy Ummels
- Medical Microbiology and Infection Control, Vrije Universiteit Amsterdam, Amsterdam UMC, 1081 HZ Amsterdam, The Netherlands
| | - Corinne Ten Hagen-Jongman
- Section of Molecular Microbiology, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands
| | - Nastassja Kriel
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Science, Faculty of Medicine and Health Science, Stellenbosch University, Tygerberg, Cape Town 7505, South Africa
| | - Arnab Pain
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia.,Global Station for Zoonosis Control, GI-CoRE, Hokkaido University, 001-0020, N20 W10 Kita-ku, Sapporo, Japan
| | - Robin M Warren
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Science, Faculty of Medicine and Health Science, Stellenbosch University, Tygerberg, Cape Town 7505, South Africa
| | - Wilbert Bitter
- Section of Molecular Microbiology, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands.,Medical Microbiology and Infection Control, Vrije Universiteit Amsterdam, Amsterdam UMC, 1081 HZ Amsterdam, The Netherlands
| | - Tiaan Heunis
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Science, Faculty of Medicine and Health Science, Stellenbosch University, Tygerberg, Cape Town 7505, South Africa.,Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Samantha L Sampson
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Science, Faculty of Medicine and Health Science, Stellenbosch University, Tygerberg, Cape Town 7505, South Africa
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8
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Ortega Ugalde S, Boot M, Commandeur JNM, Jennings P, Bitter W, Vos JC. Function, essentiality, and expression of cytochrome P450 enzymes and their cognate redox partners in Mycobacterium tuberculosis: are they drug targets? Appl Microbiol Biotechnol 2019; 103:3597-3614. [PMID: 30810776 PMCID: PMC6469627 DOI: 10.1007/s00253-019-09697-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/08/2019] [Accepted: 02/10/2019] [Indexed: 11/26/2022]
Abstract
This review covers the current knowledge of the cytochrome P450 enzymes (CYPs) of the human pathogen Mycobacterium tuberculosis (Mtb) and their endogenous redox partners, focusing on their biological function, expression, regulation, involvement in antibiotic resistance, and suitability for exploitation as antitubercular targets. The Mtb genome encodes twenty CYPs and nine associated redox partners required for CYP catalytic activity. Transposon insertion mutagenesis studies have established the (conditional) essentiality of several of these enzymes for in vitro growth and host infection. Biochemical characterization of a handful of Mtb CYPs has revealed that they have specific physiological functions in bacterial virulence and persistence in the host. Analysis of the transcriptional response of Mtb CYPs and redox partners to external insults and to first-line antibiotics used to treat tuberculosis showed a diverse expression landscape, suggesting for some enzymes a potential role in drug resistance. Combining the knowledge about the physiological roles and expression profiles indicates that, at least five Mtb CYPs, CYP121A1, CYP125A1, CYP139A1, CYP142A1, and CYP143A1, as well as two ferredoxins, FdxA and FdxC, can be considered promising novel therapeutic targets.
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Affiliation(s)
- Sandra Ortega Ugalde
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
| | - Maikel Boot
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Jan N M Commandeur
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Paul Jennings
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Wilbert Bitter
- Section of Molecular Microbiology, AIMMS, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands
| | - J Chris Vos
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
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9
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Weinert LA, Welch JJ. Why Might Bacterial Pathogens Have Small Genomes? Trends Ecol Evol 2017; 32:936-947. [PMID: 29054300 DOI: 10.1016/j.tree.2017.09.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 12/31/2022]
Abstract
Bacteria that cause serious disease often have smaller genomes, and fewer genes, than their nonpathogenic, or less pathogenic relatives. Here, we review evidence for the generality of this association, and summarise the various reasons why the association might hold. We focus on the population genetic processes that might lead to reductive genome evolution, and show how several of these could be connected to pathogenicity. We find some evidence for most of the processes having acted in bacterial pathogens, including several different modes of genome reduction acting in the same lineage. We argue that predictable processes of genome evolution might not reflect any common underlying process.
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Affiliation(s)
- Lucy A Weinert
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
| | - John J Welch
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
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10
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Camassa S, Palucci I, Iantomasi R, Cubeddu T, Minerva M, De Maio F, Jouny S, Petruccioli E, Goletti D, Ria F, Sali M, Sanguinetti M, Manganelli R, Rocca S, Brodin P, Delogu G. Impact of pe_pgrs33 Gene Polymorphisms on Mycobacterium tuberculosis Infection and Pathogenesis. Front Cell Infect Microbiol 2017; 7:137. [PMID: 28484686 PMCID: PMC5399086 DOI: 10.3389/fcimb.2017.00137] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 04/04/2017] [Indexed: 11/13/2022] Open
Abstract
PE_PGRS33 is a surface-exposed protein of Mycobacterium tuberculosis (Mtb) which exerts its role in macrophages entry and immunomodulation. In this study, we aimed to investigate the polymorphisms in the pe_pgrs33 gene of Mtb clinical isolates and evaluate their impact on protein functions. We sequenced pe_pgrs33 in a collection of 135 clinical strains, genotyped by 15-loci MIRU-VNTR and spoligotyping and belonging to the Mtb complex (MTBC). Overall, an association between pe_pgrs33 alleles and MTBC genotypes was observed and a dN/dS ratio of 0.64 was obtained, suggesting that a purifying selective pressure is acting on pe_pgrs33 against deleterious SNPs. Among a total of 19 pe_pgrs33 alleles identified in this study, 5 were cloned and used to complement the pe_pgrs33 knock-out mutant strain of Mtb H37Rv (MtbΔ33) to assess the functional impact of the respective polymorphisms in in vitro infections of primary macrophages. In human monocyte-derived macrophages (MDMs) infection, large in-frame and frameshift mutations were unable to restore the phenotype of Mtb H37Rv, impairing the cell entry capacity of Mtb, but neither its intracellular replication rate nor its immunomodulatory properties. In vivo studies performed in the murine model of tuberculosis (TB) demonstrated that the MtbΔ33 mutant strain was not impaired in the ability to infect and replicate in the lung tissue compared to the parental strain. Interestingly, MtbΔ33 showed an enhanced virulence during the chronic steps of infection compared to Mtb H37Rv. Similarly, the complementation of MtbΔ33 with a frameshift allele also resulted in a Mtb strain capable of causing a surprisingly enhanced tissue damage in murine lungs, during the chronic steps of infection. Together, these results further support the role of PE_PGRS33 in the pathogenesis and virulence of Mtb.
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Affiliation(s)
- Serena Camassa
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | - Ivana Palucci
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | - Raffaella Iantomasi
- Univ. Lille, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de LilleLille, France
| | - Tiziana Cubeddu
- Department of Veterinary Medicine, University of SassariSassari, Italy
| | - Mariachiara Minerva
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | - Flavio De Maio
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | - Samuel Jouny
- Univ. Lille, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de LilleLille, France
| | - Elisa Petruccioli
- Translational Research Unit, Department of Epidemiology and Preclinical Research, "Lazzaro Spallanzani" National Institute for Infectious DiseasesRome, Italy
| | - Delia Goletti
- Translational Research Unit, Department of Epidemiology and Preclinical Research, "Lazzaro Spallanzani" National Institute for Infectious DiseasesRome, Italy
| | - Francesco Ria
- Institute of General Pathology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | - Michela Sali
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | - Maurizio Sanguinetti
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
| | | | - Stefano Rocca
- Department of Veterinary Medicine, University of SassariSassari, Italy
| | - Priscille Brodin
- Univ. Lille, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de LilleLille, France
| | - Giovanni Delogu
- Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy
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11
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Yuan L, Su Y, Zhou S, Feng Y, Guo W, Wang X. A RACK1-like protein regulates hyphal morphogenesis, root entry and in vivo virulence in Verticillium dahliae. Fungal Genet Biol 2017; 99:52-61. [PMID: 28089629 DOI: 10.1016/j.fgb.2017.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 11/28/2016] [Accepted: 01/08/2017] [Indexed: 02/07/2023]
Abstract
To identify key genes expressed in Verticillium dahliae in early stages of infection of cotton roots, spore suspensions of eight V. dahliae isolates with different virulence levels were induced by cotton roots and genes expressed in these isolates during the early stages of infection were profiled. A gene that was differentially expressed between highly and less virulent strains was identified. Cloning and bioinformatics analysis of the gene suggested that it belongs to the putative Gβ-like/RACK1 protein family, and has seven WD40 domains. Targeted deletion of the gene revealed that it controls a number of growth-related phenotypes, including conidia and microsclerotia production, normal spore germination and hyphal development. RACK1 is a component of eukaryotic ribosomes, and here we found by qRT-PCR that disruption of RACK1 in V. dahliae (designated VdRACK1) significantly altered the transcriptional levels of other ribosomal proteins, suggesting possible global effects of VdRACK1 deletion on the protein translation of other genes. VdRACK1-null mutants lost the ability to penetrate intact cotton roots. However, the mutant strain was able to infect root-wounded cotton plants and, intriguingly, resulted in a hypervirulent phenotype, implicating a role for VdRACK1 in the restriction of rampant growth within the plant.
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Affiliation(s)
- Lei Yuan
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yaxin Su
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuai Zhou
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yigao Feng
- State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Wangzhen Guo
- State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinyu Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
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12
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Sogi KM, Holsclaw CM, Fragiadakis GK, Nomura DK, Leary JA, Bertozzi CR. Biosynthesis and Regulation of Sulfomenaquinone, a Metabolite Associated with Virulence in Mycobacterium tuberculosis. ACS Infect Dis 2016; 2:800-806. [PMID: 27933784 DOI: 10.1021/acsinfecdis.6b00106] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Sulfomenaquinone (SMK) is a recently identified metabolite that is unique to the Mycobacterium tuberculosis (M. tuberculosis) complex and is shown to modulate its virulence. Here, we report the identification of the SMK biosynthetic operon that, in addition to a previously identified sulfotransferase stf3, includes a putative cytochrome P450 gene (cyp128) and a gene of unknown function, rv2269c. We demonstrate that cyp128 and stf3 are sufficient for the biosynthesis of SMK from menaquinone and rv2269c exhibits promoter activity in M. tuberculosis. Loss of Stf3 expression, but not that of Cyp128, is correlated with elevated levels of menaquinone-9, an essential component in the electron-transport chain in M. tuberculosis. Finally, we showed in a mouse model of infection that the loss of cyp128 exhibits a hypervirulent phenotype similar to that in previous studies of the stf3 mutant. These findings provide a platform for defining the molecular basis of SMK's role in M. tuberculosis pathogenesis.
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Affiliation(s)
| | | | | | - Daniel K. Nomura
- Department
of Nutritional Science and Toxicology, University of California, Berkeley, 127 Morgan Hall, Berkeley, California 94720, United States
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13
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Jhingan GD, Kumari S, Jamwal SV, Kalam H, Arora D, Jain N, Kumaar LK, Samal A, Rao KVS, Kumar D, Nandicoori VK. Comparative Proteomic Analyses of Avirulent, Virulent, and Clinical Strains of Mycobacterium tuberculosis Identify Strain-specific Patterns. J Biol Chem 2016; 291:14257-14273. [PMID: 27151218 PMCID: PMC4933181 DOI: 10.1074/jbc.m115.666123] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 03/17/2016] [Indexed: 12/22/2022] Open
Abstract
Mycobacterium tuberculosis is an adaptable intracellular pathogen, existing in both dormant as well as active disease-causing states. Here, we report systematic proteomic analyses of four strains, H37Ra, H37Rv, and clinical isolates BND and JAL, to determine the differences in protein expression patterns that contribute to their virulence and drug resistance. Resolution of lysates of the four strains by liquid chromatography, coupled to mass spectrometry analysis, identified a total of 2161 protein groups covering ∼54% of the predicted M. tuberculosis proteome. Label-free quantification analysis of the data revealed 257 differentially expressed protein groups. The differentially expressed protein groups could be classified into seven K-means cluster bins, which broadly delineated strain-specific variations. Analysis of the data for possible mechanisms responsible for drug resistance phenotype of JAL suggested that it could be due to a combination of overexpression of proteins implicated in drug resistance and the other factors. Expression pattern analyses of transcription factors and their downstream targets demonstrated substantial differential modulation in JAL, suggesting a complex regulatory mechanism. Results showed distinct variations in the protein expression patterns of Esx and mce1 operon proteins in JAL and BND strains, respectively. Abrogating higher levels of ESAT6, an important Esx protein known to be critical for virulence, in the JAL strain diminished its virulence, although it had marginal impact on the other strains. Taken together, this study reveals that strain-specific variations in protein expression patterns have a meaningful impact on the biology of the pathogen.
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Affiliation(s)
- Gagan Deep Jhingan
- National Institute of Immunology, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | - Sangeeta Kumari
- National Institute of Immunology, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | - Shilpa V Jamwal
- Drug Discovery Research Center, Translational Health Science and Technology Institute, Faridabad, Haryana 121004
| | - Haroon Kalam
- Cellular Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | - Divya Arora
- National Institute of Immunology, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | - Neharika Jain
- Cellular Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | | | - Areejit Samal
- Institute of Mathematical Sciences, Chennai 600113, India
| | - Kanury V S Rao
- Cellular Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | - Dhiraj Kumar
- Cellular Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067
| | - Vinay Kumar Nandicoori
- National Institute of Immunology, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067.
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14
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Identification of a Transcription Factor That Regulates Host Cell Exit and Virulence of Mycobacterium tuberculosis. PLoS Pathog 2016; 12:e1005652. [PMID: 27191591 PMCID: PMC4871555 DOI: 10.1371/journal.ppat.1005652] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/01/2016] [Indexed: 02/04/2023] Open
Abstract
The interaction of Mycobacterium tuberculosis (Mtb) with host cell death signaling pathways is characterized by an initial anti-apoptotic phase followed by a pro-necrotic phase to allow for host cell exit of the bacteria. The bacterial modulators regulating necrosis induction are poorly understood. Here we describe the identification of a transcriptional repressor, Rv3167c responsible for regulating the escape of Mtb from the phagosome. Increased cytosolic localization of MtbΔRv3167c was accompanied by elevated levels of mitochondrial reactive oxygen species and reduced activation of the protein kinase Akt, and these events were critical for the induction of host cell necrosis and macroautophagy. The increase in necrosis led to an increase in bacterial virulence as reflected in higher bacterial burden and reduced survival of mice infected with MtbΔRv3167c. The regulon of Rv3167c thus contains the bacterial mediators involved in escape from the phagosome and host cell necrosis induction, both of which are crucial steps in the intracellular lifecycle and virulence of Mtb. Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is a highly successful human pathogen. Following entry into host phagocytic cells, Mtb resides within a modified phagosomal compartment and inhibits apoptotic host cell death. Recent studies have demonstrated that Mtb eventually translocates from the phagosomal compartment to the cytosol. This event is followed by the induction of necrotic host cell death allowing the bacteria to exit the host cell and infect naive cell populations. Our study adds to this relatively unexplored aspect of Mtb pathogenesis by revealing that the transcriptional repressor Rv3167c of Mtb negatively regulates phagosomal escape and host cell necrosis. We furthermore demonstrate that the increased necrosis induction by the Mtb mutant strain deficient in Rv3167c required elevated reactive oxygen species levels within host cell mitochondria and reduced activation of the protein kinase Akt. In addition, the increased virulence of the Mtb mutant strain observed after aerosol infection of mice strengthens the link between the ability of the bacteria to induce host cell necrosis and virulence. The Mtb genes negatively regulated by Rv3167c are thus potential virulence factors that can be targeted for drug and vaccine development.
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15
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Brown NA, Urban M, Hammond-Kosack KE. The trans-kingdom identification of negative regulators of pathogen hypervirulence. FEMS Microbiol Rev 2016; 40:19-40. [PMID: 26468211 PMCID: PMC4703069 DOI: 10.1093/femsre/fuv042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/30/2015] [Accepted: 09/03/2015] [Indexed: 01/08/2023] Open
Abstract
Modern society and global ecosystems are increasingly under threat from pathogens, which cause a plethora of human, animal, invertebrate and plant diseases. Of increasing concern is the trans-kingdom tendency for increased pathogen virulence that is beginning to emerge in natural, clinical and agricultural settings. The study of pathogenicity has revealed multiple examples of convergently evolved virulence mechanisms. Originally described as rare, but increasingly common, are interactions where a single gene deletion in a pathogenic species causes hypervirulence. This review utilised the pathogen-host interaction database (www.PHI-base.org) to identify 112 hypervirulent mutations from 37 pathogen species, and subsequently interrogates the trans-kingdom, conserved, molecular, biochemical and cellular themes that cause hypervirulence. This study investigates 22 animal and 15 plant pathogens including 17 bacterial and 17 fungal species. Finally, the evolutionary significance and trans-kingdom requirement for negative regulators of hypervirulence and the implication of pathogen hypervirulence and emerging infectious diseases on society are discussed.
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Affiliation(s)
- Neil A Brown
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK
| | - Martin Urban
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK
| | - Kim E Hammond-Kosack
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK
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16
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Laouami S, Clair G, Armengaud J, Duport C. Proteomic evidences for rex regulation of metabolism in toxin-producing Bacillus cereus ATCC 14579. PLoS One 2014; 9:e107354. [PMID: 25216269 PMCID: PMC4162614 DOI: 10.1371/journal.pone.0107354] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/14/2014] [Indexed: 01/07/2023] Open
Abstract
The facultative anaerobe, Bacillus cereus, causes diarrheal diseases in humans. Its ability to deal with oxygen availability is recognized to be critical for pathogenesis. The B. cereus genome comprises a gene encoding a protein with high similarities to the redox regulator, Rex, which is a central regulator of anaerobic metabolism in Bacillus subtilis and other Gram-positive bacteria. Here, we showed that B. cereus rex is monocistronic and down-regulated in the absence of oxygen. The protein encoded by rex is an authentic Rex transcriptional factor since its DNA binding activity depends on the NADH/NAD+ ratio. Rex deletion compromised the ability of B. cereus to cope with external oxidative stress under anaerobiosis while increasing B. cereus resistance against such stress under aerobiosis. The deletion of rex affects anaerobic fermentative and aerobic respiratory metabolism of B. cereus by decreasing and increasing, respectively, the carbon flux through the NADH-recycling lactate pathway. We compared both the cellular proteome and exoproteome of the wild-type and Δrex cells using a high throughput shotgun label-free quantitation approach and identified proteins that are under control of Rex-mediated regulation. Proteomics data have been deposited to the ProteomeXchange with identifier PXD000886. The data suggest that Rex regulates both the cross-talk between metabolic pathways that produce NADH and NADPH and toxinogenesis, especially in oxic conditions.
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Affiliation(s)
- Sabrina Laouami
- Avignon Université/INRA, SQPOV UMR408, Avignon, France
- INRA, SQPOV UMR408, Avignon, France
| | - Géremy Clair
- Avignon Université/INRA, SQPOV UMR408, Avignon, France
- INRA, SQPOV UMR408, Avignon, France
- Laboratoire de Biochimie des Systèmes Perturbés, CEA Marcoule, DSV-iBEB-SBTN-LBSP, Bagnols-sur-Cèze, France
| | - Jean Armengaud
- Laboratoire de Biochimie des Systèmes Perturbés, CEA Marcoule, DSV-iBEB-SBTN-LBSP, Bagnols-sur-Cèze, France
| | - Catherine Duport
- Avignon Université/INRA, SQPOV UMR408, Avignon, France
- INRA, SQPOV UMR408, Avignon, France
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17
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Clark LC, Seipke RF, Prieto P, Willemse J, van Wezel GP, Hutchings MI, Hoskisson PA. Mammalian cell entry genes in Streptomyces may provide clues to the evolution of bacterial virulence. Sci Rep 2013; 3:1109. [PMID: 23346366 PMCID: PMC3552289 DOI: 10.1038/srep01109] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 12/06/2012] [Indexed: 11/09/2022] Open
Abstract
Understanding the evolution of virulence is key to appreciating the role specific loci play in pathogenicity. Streptomyces species are generally non-pathogenic soil saprophytes, yet within their genome we can find homologues of virulence loci. One example of this is the mammalian cell entry (mce) locus, which has been characterised in Mycobacterium tuberculosis. To investigate the role in Streptomyces we deleted the mce locus and studied its impact on cell survival, morphology and interaction with other soil organisms. Disruption of the mce cluster resulted in virulence towards amoebae (Acanthamoeba polyphaga) and reduced colonization of plant (Arabidopsis) models, indicating these genes may play an important role in Streptomyces survival in the environment. Our data suggest that loss of mce in Streptomyces spp. may have profound effects on survival in a competitive soil environment, and provides insight in to the evolution and selection of these genes as virulence factors in related pathogenic organisms.
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Affiliation(s)
- Laura C Clark
- Strathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, Glasgow, UK
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18
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Kumar D, Palaniyandi K, Challu VK, Kumar P, Narayanan S. PknE, a serine/threonine protein kinase from Mycobacterium tuberculosis has a role in adaptive responses. Arch Microbiol 2012; 195:75-80. [DOI: 10.1007/s00203-012-0848-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 09/25/2012] [Accepted: 10/08/2012] [Indexed: 10/27/2022]
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19
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Zeng J, Cui T, He ZG. A genome-wide regulator-DNA interaction network in the human pathogen Mycobacterium tuberculosis H37Rv. J Proteome Res 2012; 11:4682-92. [PMID: 22808930 DOI: 10.1021/pr3006233] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Transcription regulation translates static genome information to dynamic cell behaviors, making it central to understand how cells interact with and adapt to their environment. However, only a limited number of transcription regulators and their target genes have been identified in the pathogen Mycobacterium tuberculosis , which has greatly impeded our understanding of its pathogenesis and virulence. In this study, we constructed a genome-wide transcription regulatory network of M. tuberculosis H37Rv using a high-throughput bacterial one-hybrid technique. A transcription factor skeleton network was derived on the basis of the identification of more than 5400 protein-DNA interactions. Our findings further highlight the regulatory mechanism of the mammalian cell entry 1 (mce1) module, which includes mce1R and the mce1 operon. Mce1R was linked to global negative regulation of cell growth, but was found to be positively regulated by the dormancy response regulator DevR. Expression of the mce1 operon was shown to be negatively regulated by the virulence regulator PhoP. These findings provide important new insights into the molecular mechanisms of several mce1 module-related hypervirulence phenotypes of the pathogen. Furthermore, a model of mce1 module-centered signal circuit for dormancy regulation in M. tuberculosis is proposed and discussed.
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Affiliation(s)
- Jumei Zeng
- National Key Laboratory of Agricultural Microbiology, Center for Proteomics Research, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
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20
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Deletion of an ATP-binding cassette protein subfamily C transporter in Leishmania donovani results in increased virulence. Mol Biochem Parasitol 2012; 185:165-9. [PMID: 22841683 DOI: 10.1016/j.molbiopara.2012.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/18/2012] [Accepted: 07/20/2012] [Indexed: 02/07/2023]
Abstract
Genome comparison of Leishmania species sequenced to date has identified several hundred differentially distributed genes which are present as functional genes in some species but as pseudogenes or absent in others. It is not clear whether these differentially distributed genes are important for disease, redundant or even harmful for a particular Leishmania species though a few of these genes have been implicated in Leishmania infection tissue tropism. The L. infantum LinJ.24.1510 gene is an ATP-binding cassette transporter protein subfamily C member which is present in L. donovani complex species and L. mexicana but absent in L. major and L. braziliensis and its substrate is unknown. Experimental deletion of this gene from L. donovani has resulted in an increase in growth as axenic amastigotes and increased virulence in infecting mice. To our knowledge, this is the first gene identified in Leishmania where its deletion results in hypervirulence.
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21
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Gilmore S, Schelle MW, Holsclaw CM, Leigh CD, Jain M, Cox J, Leary JA, Bertozzi CR. Sulfolipid-1 biosynthesis restricts Mycobacterium tuberculosis growth in human macrophages. ACS Chem Biol 2012; 7:863-70. [PMID: 22360425 PMCID: PMC3355658 DOI: 10.1021/cb200311s] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 02/14/2012] [Indexed: 11/29/2022]
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is a highly evolved human pathogen characterized by its formidable cell wall. Many unique lipids and glycolipids from the Mtb cell wall are thought to be virulence factors that mediate host-pathogen interactions. An intriguing example is Sulfolipid-1 (SL-1), a sulfated glycolipid that has been implicated in Mtb pathogenesis, although no direct role for SL-1 in virulence has been established. Previously, we described the biochemical activity of the sulfotransferase Stf0 that initiates SL-1 biosynthesis. Here we show that a stf0-deletion mutant exhibits augmented survival in human but not murine macrophages, suggesting that SL-1 negatively regulates the intracellular growth of Mtb in a species-specific manner. Furthermore, we demonstrate that SL-1 plays a role in mediating the susceptibility of Mtb to a human cationic antimicrobial peptide in vitro, despite being dispensable for maintaining overall cell envelope integrity. Thus, we hypothesize that the species-specific phenotype of the stf0 mutant is reflective of differences in antimycobacterial effector mechanisms of macrophages.
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Affiliation(s)
- Sarah
A. Gilmore
- Department
of Chemistry, Department of Molecular and Cell Biology, and Howard Hughes Medical Institute, University of California, Berkeley,
California 94720, United States
| | - Michael W. Schelle
- Department
of Chemistry, Department of Molecular and Cell Biology, and Howard Hughes Medical Institute, University of California, Berkeley,
California 94720, United States
| | - Cynthia M. Holsclaw
- Section
of Molecular and Cell Biology and Department of Chemistry, University of California, Davis, California 95616,
United States
| | - Clifton D. Leigh
- Department
of Chemistry, Department of Molecular and Cell Biology, and Howard Hughes Medical Institute, University of California, Berkeley,
California 94720, United States
| | - Madhulika Jain
- Department of Microbiology
and Immunology, University of California, San Francisco, California
94143, United States
| | - Jeffery
S. Cox
- Department of Microbiology
and Immunology, University of California, San Francisco, California
94143, United States
| | - Julie A. Leary
- Section
of Molecular and Cell Biology and Department of Chemistry, University of California, Davis, California 95616,
United States
| | - Carolyn R. Bertozzi
- Department
of Chemistry, Department of Molecular and Cell Biology, and Howard Hughes Medical Institute, University of California, Berkeley,
California 94720, United States
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22
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23
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Georgiades K, Merhej V, Raoult D. The influence of rickettsiologists on post-modern microbiology. Front Cell Infect Microbiol 2011; 1:8. [PMID: 22919574 PMCID: PMC3417371 DOI: 10.3389/fcimb.2011.00008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 10/10/2011] [Indexed: 11/29/2022] Open
Abstract
Many of the definitions in microbiology are currently false. We have reviewed the great denominations of microbiology and attempted to free microorganisms from the theories of the twentieth century. The presence of compartmentation and a nucleoid in Planctomycetes clearly calls into question the accuracy of the definitions of eukaryotes and prokaryotes. Archaea are viewed as prokaryotes resembling bacteria. However, the name archaea, suggesting an archaic origin of lifestyle, is inconsistent with the lifestyle of this family. Viruses are defined as small, filterable infectious agents, but giant viruses challenge the size criteria used for the definition of a virus. Pathogenicity does not require the acquisition of virulence factors (except for toxins), and in many cases, gene loss is significantly inked to the emergence of virulence. Species classification based on 16S rRNA is useless for taxonomic purposes of human pathogens, as a 2% divergence would classify all Rickettsiae within the same species and would not identify bacteria specialized for mammal infection. The use of metagenomics helps us to understand evolution and physiology by elucidating the structure, function, and interactions of the major microbial communities, but it neglects the minority populations. Finally, Darwin’s descent with modification theory, as represented by the tree of life, no longer matches our current genomic knowledge because genomics has revealed the occurrence of de novo-created genes and the mosaic structure of genomes, the Rhizome of life is therefore more appropriate.
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Affiliation(s)
- Kalliopi Georgiades
- Unité de Recherche en Maladies Infectieuses Tropical Emergentes, CNRS-IRD UMR 6236-198, Université de la Méditerranée Marseille, France.
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24
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Djelouadji Z, Raoult D, Drancourt M. Palaeogenomics of Mycobacterium tuberculosis: epidemic bursts with a degrading genome. THE LANCET. INFECTIOUS DISEASES 2011; 11:641-50. [DOI: 10.1016/s1473-3099(11)70093-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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25
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Genomes of the most dangerous epidemic bacteria have a virulence repertoire characterized by fewer genes but more toxin-antitoxin modules. PLoS One 2011; 6:e17962. [PMID: 21437250 PMCID: PMC3060909 DOI: 10.1371/journal.pone.0017962] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 02/22/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND We conducted a comparative genomic study based on a neutral approach to identify genome specificities associated with the virulence capacity of pathogenic bacteria. We also determined whether virulence is dictated by rules, or if it is the result of individual evolutionary histories. We systematically compared the genomes of the 12 most dangerous pandemic bacteria for humans ("bad bugs") to their closest non-epidemic related species ("controls"). METHODOLOGY/PRINCIPAL FINDINGS We found several significantly different features in the "bad bugs", one of which was a smaller genome that likely resulted from a degraded recombination and repair system. The 10 Cluster of Orthologous Group (COG) functional categories revealed a significantly smaller number of genes in the "bad bugs", which lacked mostly transcription, signal transduction mechanisms, cell motility, energy production and conversion, and metabolic and regulatory functions. A few genes were identified as virulence factors, including secretion system proteins. Five "bad bugs" showed a greater number of poly (A) tails compared to the controls, whereas an elevated number of poly (A) tails was found to be strongly correlated to a low GC% content. The "bad bugs" had fewer tandem repeat sequences compared to controls. Moreover, the results obtained from a principal component analysis (PCA) showed that the "bad bugs" had surprisingly more toxin-antitoxin modules than did the controls. CONCLUSIONS/SIGNIFICANCE We conclude that pathogenic capacity is not the result of "virulence factors" but is the outcome of a virulent gene repertoire resulting from reduced genome repertoires. Toxin-antitoxin systems could participate in the virulence repertoire, but they may have developed independently of selfish evolution.
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Sandegren L, Groenheit R, Koivula T, Ghebremichael S, Advani A, Castro E, Pennhag A, Hoffner S, Mazurek J, Pawlowski A, Kan B, Bruchfeld J, Melefors Ö, Källenius G. Genomic stability over 9 years of an isoniazid resistant Mycobacterium tuberculosis outbreak strain in Sweden. PLoS One 2011; 6:e16647. [PMID: 21304944 PMCID: PMC3031603 DOI: 10.1371/journal.pone.0016647] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 01/07/2011] [Indexed: 11/18/2022] Open
Abstract
In molecular epidemiological studies of drug resistant Mycobacterium tuberculosis (TB) in Sweden a large outbreak of an isoniazid resistant strain was identified, involving 115 patients, mainly from the Horn of Africa. During the outbreak period, the genomic pattern of the outbreak strain has stayed virtually unchanged with regard to drug resistance, IS6110 restriction fragment length polymorphism and spoligotyping patterns. Here we present the complete genome sequence analyses of the index isolate and two isolates sampled nine years after the index case as well as experimental data on the virulence of this outbreak strain. Even though the strain has been present in the community for nine years and passaged between patients at least five times in-between the isolates, we only found four single nucleotide polymorphisms in one of the later isolates and a small (4 amino acids) deletion in the other compared to the index isolate. In contrast to many other evolutionarily successful outbreak lineages (e.g. the Beijing lineage) this outbreak strain appears to be genetically very stable yet evolutionarily successful in a low endemic country such as Sweden. These findings further illustrate that the rate of genomic variation in TB can be highly strain dependent, something that can have important implications for epidemiological studies as well as development of resistance.
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Affiliation(s)
- Linus Sandegren
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
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Relman DA. The biological century: coming to terms with risk in the life sciences. Nat Immunol 2010; 11:275-8. [PMID: 20300132 DOI: 10.1038/ni0410-275] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David A Relman
- Department of Medicine, Stanford University, and the Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA.
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de Souza GA, Fortuin S, Aguilar D, Pando RH, McEvoy CRE, van Helden PD, Koehler CJ, Thiede B, Warren RM, Wiker HG. Using a label-free proteomics method to identify differentially abundant proteins in closely related hypo- and hypervirulent clinical Mycobacterium tuberculosis Beijing isolates. Mol Cell Proteomics 2010; 9:2414-23. [PMID: 20190197 PMCID: PMC2984234 DOI: 10.1074/mcp.m900422-mcp200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Although the genome of the Mycobacterium tuberculosis H37Rv laboratory strain has been available for over 10 years, it is only recently that genomic information from clinical isolates has been used to generate the hypothesis of virulence differences between different strains. In addition, the relationship between strains displaying differing virulence in an epidemiological setting and their behavior in animal models has received little attention. The potential causes for variation in virulence between strains, as determined by differential protein expression, have similarly been a neglected area of investigation. In this study, we used a label-free quantitative proteomics approach to estimate differences in protein abundance between two closely related Beijing genotypes that have been shown to be hyper- and hypovirulent on the basis of both epidemiological and mouse model studies. We were able to identify a total of 1668 proteins from both samples, and protein abundance calculations revealed that 48 proteins were over-represented in the hypovirulent isolate, whereas 53 were over-represented in the hypervirulent. Functional classification of these results shows that molecules of cell wall organization and DNA transcription regulatory proteins may have a critical influence in defining the level of virulence. The reduction in the presence of ESAT-6, other Esx-like proteins, and FbpD (MPT51) in the hypervirulent strain indicates that changes in the repertoire of highly immunogenic proteins can be a defensive process undertaken by the virulent cell. In addition, most of the previously well characterized gene targets related to virulence were found to be similarly expressed in our model. Our data support the use of proteomics as a complementary tool for genomic comparisons to understand the biology of M. tuberculosis virulence.
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Affiliation(s)
- Gustavo A de Souza
- Section for Microbiology and Immunology, The Gade Institute, University of Bergen, Bergen, Norway
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McEvoy CRE, van Helden PD, Warren RM, van Pittius NCG. Evidence for a rapid rate of molecular evolution at the hypervariable and immunogenic Mycobacterium tuberculosis PPE38 gene region. BMC Evol Biol 2009; 9:237. [PMID: 19769792 PMCID: PMC2758852 DOI: 10.1186/1471-2148-9-237] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Accepted: 09/21/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND PPE38 (Rv2352c) is a member of the large PPE gene family of Mycobacterium tuberculosis and related mycobacteria. The function of PPE proteins is unknown but evidence suggests that many are cell-surface associated and recognised by the host immune system. Previous studies targeting other PPE gene members suggest that some display high levels of polymorphism and it is thought that this might represent a means of providing antigenic variation. We have analysed the genetic variability of the PPE38 genomic region on a cohort of M. tuberculosis clinical isolates representing all of the major phylogenetic lineages, along with the ancestral M. tuberculosis complex (MTBC) member M. canettii, and supplemented this with analysis of publicly available whole genome sequences representing additional M. tuberculosis clinical isolates, other MTBC members and non tuberculous mycobacteria (NTM). Where possible we have extended this analysis to include the adjacent plcABC and PPE39/40 genomic regions. RESULTS We show that the ancestral MTBC PPE38 region comprises 2 homologous PPE genes (PPE38 and PPE71), separated by 2 esat-6 (esx)-like genes and that this structure derives from an esx/esx/PPE duplication in the common ancestor of M. tuberculosis and M. marinum. We also demonstrate that this region of the genome is hypervariable due to frequent IS6110 integration, IS6110-associated recombination, and homologous recombination and gene conversion events between PPE38 and PPE71. These mutations result in combinations of gene deletion, gene truncation and gene disruption in the majority of clinical isolates. These mutations were generally found to be IS6110 strain lineage-specific, although examples of additional within-lineage and even within-cluster mutations were observed. Furthermore, we provide evidence that the published M. tuberculosis H37Rv whole genome sequence is inaccurate regarding this region. CONCLUSION Our results show that this antigen-encoding region of the M. tuberculosis genome is hypervariable. The observation that numerous different mutations have become fixed within specific lineages demonstrates that this genomic region is undergoing rapid molecular evolution and that further lineage-specific evolutionary expansion and diversification has occurred subsequent to the lineage-defining mutational events. We predict that functional loss of these genes could aid immune evasion. Finally, we also show that the PPE38 region of the published M. tuberculosis H37Rv whole genome sequence is not representative of the ATCC H37Rv reference strain.
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Affiliation(s)
- Christopher RE McEvoy
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
| | - Paul D van Helden
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
| | - Robin M Warren
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
| | - Nicolaas C Gey van Pittius
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
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Abstract
There is a wide range of animal models of tuberculosis; which is fortunate, given that there is a wide range of complex biological phenomena to model. Nonetheless, the inadequacy of animal models is a chronic grievance amongst researchers, often expressed in the conclusion that the mouse is not a good model of human tuberculosis. There clearly are major differences between experimental infection of mice and natural infection of humans, but this overarching dogma is inconducive to fruitful research.
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Affiliation(s)
- Douglas Young
- Division of Mycobacterial Research, MRC National Institute for Medical Research, London, UK.
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Ouellet H, Johnston JB, Ortiz de Montellano PR. The Mycobacterium tuberculosis cytochrome P450 system. Arch Biochem Biophys 2009; 493:82-95. [PMID: 19635450 DOI: 10.1016/j.abb.2009.07.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 07/17/2009] [Accepted: 07/21/2009] [Indexed: 11/25/2022]
Abstract
Tuberculosis remains a leading cause of human mortality. The emergence of strains of Mycobacterium tuberculosis, the causative agent, that are resistant to the major frontline antitubercular drugs increases the urgency for the development of new therapeutic agents. Sequencing of the M. tuberculosis genome revealed the existence of 20 cytochrome P450 enzymes, some of which are potential candidates for drug targeting. The recent burst of studies reporting microarray-based gene essentiality and transcriptome analyses under in vitro, ex vivo and in vivo conditions highlight the importance of selected P450 isoforms for M. tuberculosis viability and pathogenicity. Current knowledge of the structural and biochemical properties of the M. tuberculosis P450 enzymes and their putative redox partners is reviewed, with an emphasis on findings related to their physiological function(s) as well as their potential as drug targets.
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Affiliation(s)
- Hugues Ouellet
- Department of Pharmaceutical Chemistry, University of California San Francisco, 600 16th Street, San Francisco, CA 94158-2517, USA
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Wilkinson P, Waterfield NR, Crossman L, Corton C, Sanchez-Contreras M, Vlisidou I, Barron A, Bignell A, Clark L, Ormond D, Mayho M, Bason N, Smith F, Simmonds M, Churcher C, Harris D, Thompson NR, Quail M, Parkhill J, Ffrench-Constant RH. Comparative genomics of the emerging human pathogen Photorhabdus asymbiotica with the insect pathogen Photorhabdus luminescens. BMC Genomics 2009; 10:302. [PMID: 19583835 PMCID: PMC2717986 DOI: 10.1186/1471-2164-10-302] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 07/07/2009] [Indexed: 01/05/2023] Open
Abstract
Background The Gram-negative bacterium Photorhabdus asymbiotica (Pa) has been recovered from human infections in both North America and Australia. Recently, Pa has been shown to have a nematode vector that can also infect insects, like its sister species the insect pathogen P. luminescens (Pl). To understand the relationship between pathogenicity to insects and humans in Photorhabdus we have sequenced the complete genome of Pa strain ATCC43949 from North America. This strain (formerly referred to as Xenorhabdus luminescens strain 2) was isolated in 1977 from the blood of an 80 year old female patient with endocarditis, in Maryland, USA. Here we compare the complete genome of Pa ATCC43949 with that of the previously sequenced insect pathogen P. luminescens strain TT01 which was isolated from its entomopathogenic nematode vector collected from soil in Trinidad and Tobago. Results We found that the human pathogen Pa had a smaller genome (5,064,808 bp) than that of the insect pathogen Pl (5,688,987 bp) but that each pathogen carries approximately one megabase of DNA that is unique to each strain. The reduced size of the Pa genome is associated with a smaller diversity in insecticidal genes such as those encoding the Toxin complexes (Tc's), Makes caterpillars floppy (Mcf) toxins and the Photorhabdus Virulence Cassettes (PVCs). The Pa genome, however, also shows the addition of a plasmid related to pMT1 from Yersinia pestis and several novel pathogenicity islands including a novel Type Three Secretion System (TTSS) encoding island. Together these data suggest that Pa may show virulence against man via the acquisition of the pMT1-like plasmid and specific effectors, such as SopB, that promote its persistence inside human macrophages. Interestingly the loss of insecticidal genes in Pa is not reflected by a loss of pathogenicity towards insects. Conclusion Our results suggest that North American isolates of Pa have acquired virulence against man via the acquisition of a plasmid and specific virulence factors with similarity to those shown to play roles in pathogenicity against humans in other bacteria.
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Affiliation(s)
- Paul Wilkinson
- School of Biosciences, University of Exeter in Cornwall, Penryn TR10 9EZ, UK.
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Merhej V, Royer-Carenzi M, Pontarotti P, Raoult D. Massive comparative genomic analysis reveals convergent evolution of specialized bacteria. Biol Direct 2009; 4:13. [PMID: 19361336 PMCID: PMC2688493 DOI: 10.1186/1745-6150-4-13] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 04/10/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genome size and gene content in bacteria are associated with their lifestyles. Obligate intracellular bacteria (i.e., mutualists and parasites) have small genomes that derived from larger free-living bacterial ancestors; however, the different steps of bacterial specialization from free-living to intracellular lifestyle have not been studied comprehensively. The growing number of available sequenced genomes makes it possible to perform a statistical comparative analysis of 317 genomes from bacteria with different lifestyles. RESULTS Compared to free-living bacteria, host-dependent bacteria exhibit fewer rRNA genes, more split rRNA operons and fewer transcriptional regulators, linked to slower growth rates. We found a function-dependent and non-random loss of the same 100 orthologous genes in all obligate intracellular bacteria. Thus, we showed that obligate intracellular bacteria from different phyla are converging according to their lifestyle. Their specialization is an irreversible phenomenon characterized by translation modification and massive gene loss, including the loss of transcriptional regulators. Although both mutualists and parasites converge by genome reduction, these obligate intracellular bacteria have lost distinct sets of genes in the context of their specific host associations: mutualists have significantly more genes that enable nutrient provisioning whereas parasites have genes that encode Types II, IV, and VI secretion pathways. CONCLUSION Our findings suggest that gene loss, rather than acquisition of virulence factors, has been a driving force in the adaptation of parasites to eukaryotic cells. This comparative genomic analysis helps to explore the strategies by which obligate intracellular genomes specialize to particular host-associations and contributes to advance our knowledge about the mechanisms of bacterial evolution.
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Affiliation(s)
- Vicky Merhej
- Faculty of Medicine, Unit for Research on Emergent and Tropical Infectious Diseases, CNRS-IRD UMR 6236 IFR48, University of the Mediterranean, Marseilles, France.
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Käser M, Pluschke G. Differential gene repertoire in Mycobacterium ulcerans identifies candidate genes for patho-adaptation. PLoS Negl Trop Dis 2008; 2:e353. [PMID: 19104652 PMCID: PMC2600814 DOI: 10.1371/journal.pntd.0000353] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 12/02/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Based on large genomic sequence polymorphisms, several haplotypes belonging to two major lineages of the human pathogen Mycobacterium ulcerans could be distinguished among patient isolates from various geographic origins. However, the biological relevance of insertional/deletional diversity is not understood. METHODOLOGY Using comparative genomics, we have investigated the genes located in regions of difference recently identified by DNA microarray based hybridisation analysis. The analysed regions of difference comprise approximately 7% of the entire M. ulcerans genome. PRINCIPAL FINDINGS Several different mechanisms leading to loss of functional genes were identified, ranging from pseudogenization, caused by frame shift mutations or mobile genetic element interspersing, to large sequence polymorphisms. Four hot spot regions for genetic instability were unveiled. Altogether, 229 coding sequences were found to be differentially inactivated, constituting a repertoire of coding sequence variation in the rather monomorphic M. ulcerans. CONCLUSIONS/SIGNIFICANCE The differential gene inactivation patterns associated with the M. ulcerans haplotypes identified candidate genes that may confer enhanced adaptation upon ablation of expression. A number of gene conversions confined to the classical lineage may contribute to particular virulence of this group comprising isolates from Africa and Australia. Identification of this spectrum of anti-virulence gene candidates expands our understanding of the pathogenicity and ecology of the emerging infectious disease Buruli ulcer.
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