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Mycobacterium marinum SecA2 promotes stable granulomas and induces tumor necrosis factor alpha in vivo. Infect Immun 2012; 80:3512-20. [PMID: 22851747 DOI: 10.1128/iai.00686-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
SecA2 is an ATPase present in some pathogenic Gram-positive bacteria, is required for translocation of a limited set of proteins across the cytosolic membrane, and plays an important role in virulence in several bacteria, including mycobacteria that cause diseases such as tuberculosis and leprosy. However, the mechanisms by which SecA2 affects virulence are incompletely understood. To investigate whether SecA2 modulates host immune responses in vivo, we studied Mycobacterium marinum infection in two different hosts: an established zebrafish model and a recently described mouse model. Here we show that M. marinum ΔsecA2 was attenuated for virulence in both host species and SecA2 was needed for normal granuloma numbers and for optimal tumor necrosis factor alpha response in both zebrafish and mice. M. marinum ΔsecA2 was more sensitive to SDS and had unique protrusions from its cell envelope when examined by cryo-electron tomography, suggesting that SecA2 is important for bacterial cell wall integrity. These results provide evidence that SecA2 induces granulomas and is required for bacterial modulation of the host response because it affects the mycobacterial cell envelope.
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Abstract
Bacillus anthracis grows in chains of rod-shaped cells, a trait that contributes to its escape from phagocytic clearance in host tissues. Using a genetic approach to search for determinants of B. anthracis chain length, we identified mutants with insertional lesions in secA2. All isolated secA2 mutants exhibited an exaggerated chain length, whereas the dimensions of individual cells were not changed. Complementation studies revealed that slaP (S-layer assembly protein), a gene immediately downstream of secA2 on the B. anthracis chromosome, is also a determinant of chain length. Both secA2 and slaP are required for the efficient secretion of Sap and EA1 (Eag), the two S-layer proteins of B. anthracis, but not for the secretion of S-layer-associated proteins or of other secreted products. S-layer assembly via secA2 and slaP contributes to the proper positioning of BslO, the S-layer-associated protein, and murein hydrolase, which cleaves septal peptidoglycan to separate chains of bacilli. SlaP was found to be both soluble in the bacterial cytoplasm and associated with the membrane. The purification of soluble SlaP from B. anthracis-cleared lysates did not reveal a specific ligand, and the membrane association of SlaP was not dependent on SecA2, Sap, or EA1. We propose that SecA2 and SlaP promote the efficient secretion of S-layer proteins by modifying the general secretory pathway of B. anthracis to transport large amounts of Sap and EA1.
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103
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MAP1272c encodes an NlpC/P60 protein, an antigen detected in cattle with Johne's disease. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:1083-92. [PMID: 22593240 DOI: 10.1128/cvi.00195-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The protein encoded by MAP1272c has been shown to be an antigen of Mycobacterium avium subsp. paratuberculosis that contains an NlpC/P60 superfamily domain found in lipoproteins or integral membrane proteins. Proteins containing this domain have diverse enzymatic functions that include peptidases, amidases, and acetyltransferases. The NlpC protein was examined in comparison to over 100 recombinant proteins and showed the strongest antigenicity when analyzed with sera from cattle with Johne's disease. To further localize the immunogenicity of NlpC, recombinant proteins representing defined regions were expressed and evaluated with sera from cattle with Johne's disease. The region from amino acids 74 to 279 was shown to be the most immunogenic. This fragment was also evaluated against a commercially available enzyme-linked immunosorbent assay (ELISA). Two monoclonal antibodies were produced in mice immunized with the full-length protein, and each recognized a distinct epitope. These antibodies cross-reacted with proteins from other mycobacterial species and demonstrated variable sizes of the proteins expressed from these subspecies. Both antibodies were further analyzed, and their interaction with MAP1272c and MAP1204 was characterized by a solution-based, luminescent binding assay. These tools provide additional means to study a strong antigen of M. avium subsp. paratuberculosis.
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104
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Gengenbacher M, Kaufmann SHE. Mycobacterium tuberculosis: success through dormancy. FEMS Microbiol Rev 2012; 36:514-32. [PMID: 22320122 PMCID: PMC3319523 DOI: 10.1111/j.1574-6976.2012.00331.x] [Citation(s) in RCA: 476] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 12/22/2011] [Accepted: 01/31/2012] [Indexed: 01/21/2023] Open
Abstract
Tuberculosis (TB) remains a major health threat, killing nearly 2 million individuals around this globe, annually. The only vaccine, developed almost a century ago, provides limited protection only during childhood. After decades without the introduction of new antibiotics, several candidates are currently undergoing clinical investigation. Curing TB requires prolonged combination of chemotherapy with several drugs. Moreover, monitoring the success of therapy is questionable owing to the lack of reliable biomarkers. To substantially improve the situation, a detailed understanding of the cross-talk between human host and the pathogen Mycobacterium tuberculosis (Mtb) is vital. Principally, the enormous success of Mtb is based on three capacities: first, reprogramming of macrophages after primary infection/phagocytosis to prevent its own destruction; second, initiating the formation of well-organized granulomas, comprising different immune cells to create a confined environment for the host-pathogen standoff; third, the capability to shut down its own central metabolism, terminate replication, and thereby transit into a stage of dormancy rendering itself extremely resistant to host defense and drug treatment. Here, we review the molecular mechanisms underlying these processes, draw conclusions in a working model of mycobacterial dormancy, and highlight gaps in our understanding to be addressed in future research.
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Affiliation(s)
- Martin Gengenbacher
- Max Planck Institute for Infection Biology, Department of Immunology Charitéplatz 1, 10117 Berlin, Germany
| | - Stefan H. E. Kaufmann
- Max Planck Institute for Infection Biology, Department of Immunology Charitéplatz 1, 10117 Berlin, Germany
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105
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Rosenberger T, Brülle JK, Sander P. A β-Lactamase based reporter system for ESX dependent protein translocation in mycobacteria. PLoS One 2012; 7:e35453. [PMID: 22530024 PMCID: PMC3329429 DOI: 10.1371/journal.pone.0035453] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 03/16/2012] [Indexed: 01/22/2023] Open
Abstract
Protein secretion is essential for all bacteria in order to interact with their environment. Mycobacterium tuberculosis depends on protein secretion to subvert host immune response mechanisms. Both the general secretion system (Sec) and the twin-arginine translocation system (Tat) are functional in mycobacteria. Furthermore, a novel type of protein translocation system named ESX has been identified. In the genome of M. tuberculosis five paralogous ESX regions (ESX-1 to ESX-5) have been found. Several components of the ESX translocation apparatus have been identified over the last ten years. The ESX regions are composed of a basic set of genes for the translocation machinery and the main substrate - a heterodimer. The best studied of these heterodimers is EsxA (ESAT-6)/EsxB (CFP-10), which has been shown to be exported by ESX-1. EsxA/B is heavily involved in virulence of M. tuberculosis. EsxG/H is exported by ESX-3 and seems to be involved in an essential iron-uptake mechanism in M. tuberculosis. These findings make ESX-3 components high profile drug targets. Until now, reporter systems for determination of ESX protein translocation have not been developed. In order to create such a reporter system, a truncated β-lactamase (‘bla TEM-1) was fused to the N-terminus of EsxB, EsxG and EsxU, respectively. These constructs have then been tested in a β-lactamase (BlaS) deletion strain of Mycobacterium smegmatis. M. smegmatis ΔblaS is highly susceptible to ampicillin. An ampicillin resistant phenotype was conferred by translocation of Bla TEM-1-Esx fusion proteins into the periplasm. BlaTEM-1-Esx fusion proteins were not found in the culture filtrate suggesting that plasma membrane translocation and outer membrane translocation are two distinct steps in ESX secretion. Thus we have developed a powerful tool to dissect the molecular mechanisms of ESX dependent protein translocation and to screen for novel components of the ESX systems on a large scale.
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Affiliation(s)
- Tobias Rosenberger
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Juliane K. Brülle
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Peter Sander
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
- Nationales Zentrum für Mykobakterien, Zurich, Switzerland
- * E-mail:
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106
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In silico identification of epitopes in Mycobacterium avium subsp. paratuberculosis proteins that were upregulated under stress conditions. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:855-64. [PMID: 22496492 DOI: 10.1128/cvi.00114-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Johne's disease in ruminants is caused by Mycobacterium avium subsp. paratuberculosis. Diagnosis of M. avium subsp. paratuberculosis infection is difficult, especially in the early stages. To date, ideal antigen candidates are not available for efficient immunization or immunodiagnosis. This study reports the in silico selection and subsequent analysis of epitopes of M. avium subsp. paratuberculosis proteins that were found to be upregulated under stress conditions as a means to identify immunogenic candidate proteins. Previous studies have reported differential regulation of proteins when M. avium subsp. paratuberculosis is exposed to stressors which induce a response similar to dormancy. Dormancy may be involved in evading host defense mechanisms, and the host may also mount an immune response against these proteins. Twenty-five M. avium subsp. paratuberculosis proteins that were previously identified as being upregulated under in vitro stress conditions were analyzed for B and T cell epitopes by use of the prediction tools at the Immune Epitope Database and Analysis Resource. Major histocompatibility complex class I T cell epitopes were predicted using an artificial neural network method, and class II T cell epitopes were predicted using the consensus method. Conformational B cell epitopes were predicted from the relevant three-dimensional structure template for each protein. Based on the greatest number of predicted epitopes, eight proteins (MAP2698c [encoded by desA2], MAP2312c [encoded by fadE19], MAP3651c [encoded by fadE3_2], MAP2872c [encoded by fabG5_2], MAP3523c [encoded by oxcA], MAP0187c [encoded by sodA], and the hypothetical proteins MAP3567 and MAP1168c) were identified as potential candidates for study of antibody- and cell-mediated immune responses within infected hosts.
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107
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Involvement of two latex-clearing proteins during rubber degradation and insights into the subsequent degradation pathway revealed by the genome sequence of Gordonia polyisoprenivorans strain VH2. Appl Environ Microbiol 2012; 78:2874-87. [PMID: 22327575 DOI: 10.1128/aem.07969-11] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The increasing production of synthetic and natural poly(cis-1,4-isoprene) rubber leads to huge challenges in waste management. Only a few bacteria are known to degrade rubber, and little is known about the mechanism of microbial rubber degradation. The genome of Gordonia polyisoprenivorans strain VH2, which is one of the most effective rubber-degrading bacteria, was sequenced and annotated to elucidate the degradation pathway and other features of this actinomycete. The genome consists of a circular chromosome of 5,669,805 bp and a circular plasmid of 174,494 bp with average GC contents of 67.0% and 65.7%, respectively. It contains 5,110 putative protein-coding sequences, including many candidate genes responsible for rubber degradation and other biotechnically relevant pathways. Furthermore, we detected two homologues of a latex-clearing protein, which is supposed to be a key enzyme in rubber degradation. The deletion of these two genes for the first time revealed clear evidence that latex-clearing protein is essential for the microbial utilization of rubber. Based on the genome sequence, we predict a pathway for the microbial degradation of rubber which is supported by previous and current data on transposon mutagenesis, deletion mutants, applied comparative genomics, and literature search.
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108
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Oliveira L, Madureira P, Andrade EB, Bouaboud A, Morello E, Ferreira P, Poyart C, Trieu-Cuot P, Dramsi S. Group B streptococcus GAPDH is released upon cell lysis, associates with bacterial surface, and induces apoptosis in murine macrophages. PLoS One 2012; 7:e29963. [PMID: 22291899 PMCID: PMC3264557 DOI: 10.1371/journal.pone.0029963] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 12/09/2011] [Indexed: 11/18/2022] Open
Abstract
Glyceraldehyde 3-phosphate dehydrogenases (GAPDH) are cytoplasmic glycolytic enzymes that, despite lacking identifiable secretion signals, have been detected at the surface of several prokaryotic and eukaryotic organisms where they exhibit non-glycolytic functions including adhesion to host components. Group B Streptococcus (GBS) is a human commensal bacterium that has the capacity to cause life-threatening meningitis and septicemia in newborns. Electron microscopy and fluorescence-activated cell sorter (FACS) analysis demonstrated the surface localization of GAPDH in GBS. By addressing the question of GAPDH export to the cell surface of GBS strain NEM316 and isogenic mutant derivatives of our collection, we found that impaired GAPDH presence in the surface and supernatant of GBS was associated with a lower level of bacterial lysis. We also found that following GBS lysis, GAPDH can associate to the surface of many living bacteria. Finally, we provide evidence for a novel function of the secreted GAPDH as an inducer of apoptosis of murine macrophages.
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Affiliation(s)
- Liliana Oliveira
- Universidade do Porto, ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Porto, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
- Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Centre National de la Recherche Scientifique (UMR 8104), Paris, France
- Institut National de la Santé et de la Recherche Médicale, U1016, Paris, France
| | - Pedro Madureira
- Universidade do Porto, ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Porto, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Elva Bonifácio Andrade
- Universidade do Porto, ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Porto, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Abdelouhab Bouaboud
- Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Centre National de la Recherche Scientifique (UMR 8104), Paris, France
- Institut National de la Santé et de la Recherche Médicale, U1016, Paris, France
| | - Eric Morello
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram-positif, CNRS URA 2172, Paris, France
| | - Paula Ferreira
- Universidade do Porto, ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Porto, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Claire Poyart
- Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Centre National de la Recherche Scientifique (UMR 8104), Paris, France
- Institut National de la Santé et de la Recherche Médicale, U1016, Paris, France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram-positif, CNRS URA 2172, Paris, France
| | - Shaynoor Dramsi
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram-positif, CNRS URA 2172, Paris, France
- * E-mail:
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109
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Aguirre JD, Culotta VC. Battles with iron: manganese in oxidative stress protection. J Biol Chem 2012; 287:13541-8. [PMID: 22247543 DOI: 10.1074/jbc.r111.312181] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron.
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Affiliation(s)
- J Dafhne Aguirre
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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110
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The Mycobacterium tuberculosis SecA2 system subverts phagosome maturation to promote growth in macrophages. Infect Immun 2012; 80:996-1006. [PMID: 22215736 DOI: 10.1128/iai.05987-11] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ability of Mycobacterium tuberculosis to grow in macrophages is critical to the virulence of this important pathogen. One way M. tuberculosis is thought to maintain a hospitable niche in macrophages is by arresting the normal process of phagosomes maturing into acidified phagolysosomes. The process of phagosome maturation arrest by M. tuberculosis is not fully understood, and there has remained a need to firmly establish a requirement for phagosome maturation arrest for M. tuberculosis growth in macrophages. Other intracellular pathogens that control the phagosomal environment use specialized protein export systems to deliver effectors of phagosome trafficking to the host cell. In M. tuberculosis, the accessory SecA2 system is a specialized protein export system that is required for intracellular growth in macrophages. In studying the importance of the SecA2 system in macrophages, we discovered that SecA2 is required for phagosome maturation arrest. Shortly after infection, phagosomes containing a ΔsecA2 mutant of M. tuberculosis were more acidified and showed greater association with markers of late endosomes than phagosomes containing wild-type M. tuberculosis. We further showed that inhibitors of phagosome acidification rescued the intracellular growth defect of the ΔsecA2 mutant, which demonstrated that the phagosome maturation arrest defect of the ΔsecA2 mutant is responsible for the intracellular growth defect. This study demonstrates the importance of phagosome maturation arrest for M. tuberculosis growth in macrophages, and it suggests there are effectors of phagosome maturation that are exported into the host environment by the accessory SecA2 system.
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111
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Trivedi A, Singh N, Bhat SA, Gupta P, Kumar A. Redox biology of tuberculosis pathogenesis. Adv Microb Physiol 2012; 60:263-324. [PMID: 22633061 DOI: 10.1016/b978-0-12-398264-3.00004-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mycobacterium tuberculosis (Mtb) is one of the most successful human pathogens. Mtb is persistently exposed to numerous oxidoreductive stresses during its pathogenic cycle of infection and transmission. The distinctive ability of Mtb, not only to survive the redox stress manifested by the host but also to use it for synchronizing the metabolic pathways and expression of virulence factors, is central to its success as a pathogen. This review describes the paradigmatic redox and hypoxia sensors employed by Mtb to continuously monitor variations in the intracellular redox state and the surrounding microenvironment. Two component proteins, namely, DosS and DosT, are employed by Mtb to sense changes in oxygen, nitric oxide, and carbon monoxide levels, while WhiB3 and anti-sigma factor RsrA are used to monitor changes in intracellular redox state. Using these and other unidentified redox sensors, Mtb orchestrates its metabolic pathways to survive in nutrient-deficient, acidic, oxidative, nitrosative, and hypoxic environments inside granulomas or infectious lesions. A number of these metabolic pathways are unique to mycobacteria and thus represent potential drug targets. In addition, Mtb employs versatile machinery of the mycothiol and thioredoxin systems to ensure a reductive intracellular environment for optimal functioning of its proteins even upon exposure to oxidative stress. Mtb also utilizes a battery of protective enzymes, such as superoxide dismutase (SOD), catalase (KatG), alkyl hydroperoxidase (AhpC), and peroxiredoxins, to neutralize the redox stress generated by the host immune system. This chapter reviews the current understanding of mechanisms employed by Mtb to sense and neutralize redox stress and their importance in TB pathogenesis and drug development.
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112
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van der Woude AD, Luirink J, Bitter W. Getting across the cell envelope: mycobacterial protein secretion. Curr Top Microbiol Immunol 2012; 374:109-34. [PMID: 23239236 DOI: 10.1007/82_2012_298] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Protein secretion is an essential determinant of mycobacterial virulence. Mycobacterium tuberculosis has a unique cell envelope consisting of two lipid bilayers, which requires dedicated protein secretion pathways. The conserved general Sec and Tat translocation systems are responsible for protein transport across the inner membrane and are both essential. Additionally, the accessory Sec pathway specifically contributes to virulence. How transport of Sec/Tat substrates across the outer membrane is accomplished is currently an enigma. In addition to these pathways, M. tuberculosis also developed specialized secretion systems for protein transport across both membranes, the type VII or ESX secretion systems. Here, we discuss our current knowledge about the mechanisms and substrates of these different protein translocation systems and their role in mycobacterial physiology and virulence.
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Affiliation(s)
- Aniek D van der Woude
- Department of Molecular Microbiology, Institute of Molecular Cell Biology, VU University, Amsterdam, The Netherlands
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113
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Ligon LS, Hayden JD, Braunstein M. The ins and outs of Mycobacterium tuberculosis protein export. Tuberculosis (Edinb) 2011; 92:121-32. [PMID: 22192870 DOI: 10.1016/j.tube.2011.11.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 11/10/2011] [Accepted: 11/11/2011] [Indexed: 11/25/2022]
Abstract
Mycobacterium tuberculosis is an important pathogen that infects approximately one-third of the world's population and kills almost two million people annually. An important aspect of M. tuberculosis physiology and pathogenesis is its ability to export proteins into and across the thick mycobacterial cell envelope, where they are ideally positioned to interact with the host. In addition to the specific proteins that are exported by M. tuberculosis, the systems through which these proteins are exported represent potential targets for future drug development. M. tuberculosis possesses two well-known and conserved export systems: the housekeeping Sec pathway and the Tat pathway. In addition, M. tuberculosis possesses specialized export systems including the accessory SecA2 pathway and five ESX pathways. Here we review the current understanding of each of these export systems, with a focus on M. tuberculosis, and discuss the contribution of each system to disease and physiology.
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Affiliation(s)
- Lauren S Ligon
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, CB #7290, Chapel Hill, NC 27599, USA
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114
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Mishra KK, Mendonca M, Aroonnual A, Burkholder KM, Bhunia AK. Genetic organization and molecular characterization of secA2 locus in Listeria species. Gene 2011; 489:76-85. [DOI: 10.1016/j.gene.2011.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 07/13/2011] [Accepted: 08/25/2011] [Indexed: 12/01/2022]
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115
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Chen JW, Faisal SM, Chandra S, McDonough SP, Moreira MAS, Scaria J, Chang CF, Bannantine JP, Akey B, Chang YF. Immunogenicity and protective efficacy of the Mycobacterium avium subsp. paratuberculosis attenuated mutants against challenge in a mouse model. Vaccine 2011; 30:3015-25. [PMID: 22107851 DOI: 10.1016/j.vaccine.2011.11.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 11/07/2011] [Accepted: 11/08/2011] [Indexed: 10/15/2022]
Abstract
Johne's disease (JD), caused by Mycobacterium avium subsp. paratuberculosis (MAP), results in serious economic losses worldwide especially in cattle, sheep and goats. To control the impact of JD on the animal industry, an effective vaccine with minimal adverse effects is urgently required. In order to develop an effective vaccine, we used allelic exchange to construct three mutant MAP strains, leuD, mpt64 and secA2. The mutants were attenuated in a murine model and induced cytokine responses in J774A.1 cell. The leuD mutant was the most obviously attenuated of the three constructed mutant strains. Our preliminary vaccine trial in mice demonstrated different levels of protection were induced by these mutants based on the acid-fast bacilli burden in livers and spleens at 8 and 12 weeks postchallenge. In addition, vaccination with leuD mutant induced a high level of IFN-γ production and significant protective efficacy in both the reduction of inflammation and clearance of acid-fast bacilli, as compared with the mock vaccinated group.
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Affiliation(s)
- Jenn-Wei Chen
- Animal Health Diagnostic Center, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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116
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Mukhopadhyay S, Nair S, Ghosh S. Pathogenesis in tuberculosis: transcriptomic approaches to unraveling virulence mechanisms and finding new drug targets. FEMS Microbiol Rev 2011; 36:463-85. [PMID: 22092372 DOI: 10.1111/j.1574-6976.2011.00302.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 07/31/2011] [Accepted: 08/05/2011] [Indexed: 01/12/2023] Open
Abstract
Tuberculosis (TB) remains a major health problem worldwide. Attempts to control this disease have proved difficult owing to our poor understanding of the pathobiology of Mycobacterium tuberculosis and the emergence of strains that are resistant to multiple drugs currently available for treatment. Genome-wide expression profiling has provided new insight into the transcriptome signatures of the bacterium during infection, notably of macrophages and dendritic cells. These data indicate that M. tuberculosis expresses numerous genes to evade the host immune responses, to suit its intracellular life style, and to respond to various antibiotic drugs. Among the intracellularly induced genes, several have functions in lipid metabolism, cell wall synthesis, iron uptake, oxidative stress resistance, protein secretion, or inhibition of apoptosis. Herein we review these findings and discuss possible ways to exploit the data to understand the complex etiology of TB and to find new effective drug targets.
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Affiliation(s)
- Sangita Mukhopadhyay
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics, Nampally, Hyderabad, India.
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117
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Krehenbrink M, Edwards A, Downie JA. The superoxide dismutase SodA is targeted to the periplasm in a SecA-dependent manner by a novel mechanism. Mol Microbiol 2011; 82:164-79. [PMID: 21854464 DOI: 10.1111/j.1365-2958.2011.07803.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The manganese/iron-type superoxide dismutase (SodA) of Rhizobium leguminosarum bv. viciae 3841 is exported to the periplasm of R. l. bv. viciae and Escherichia coli. However, it does not possess a hydrophobic cleaved N-terminal signal peptide typically present in soluble proteins exported by the Sec-dependent (Sec) pathway or the twin-arginine translocation (TAT) pathway. A tatC mutant of R. l. bv. viciae exported SodA to the periplasm, ruling out export of SodA as a complex with a TAT substrate as a chaperone. The export of SodA was unaffected in a secB mutant of E. coli, but its export from R. l. bv. viciae was inhibited by azide, an inhibitor of SecA ATPase activity. A temperature-sensitive secA mutant of E. coli was strongly reduced for SodA export. The 10 N-terminal amino acid residues of SodA were sufficient to target the reporter protein alkaline phosphatase to the periplasm. Our results demonstrate the export of a protein lacking a classical signal peptide to the periplasm by a SecA-dependent, but SecB-independent targeting mechanism. Export of the R. l. bv. viciae SodA to the periplasm was not limited to the genus Rhizobium, but was also observed in other proteobacteria.
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Affiliation(s)
- Martin Krehenbrink
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR47UH, UK
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Priming of protective anti-Listeria monocytogenes memory CD8+ T cells requires a functional SecA2 secretion system. Infect Immun 2011; 79:2396-403. [PMID: 21402759 DOI: 10.1128/iai.00020-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The SecA2 auxiliary secretion system of Gram-positive bacteria promotes the export of virulence proteins essential for colonization of the host in the case of both Mycobacterium tuberculosis and Listeria monocytogenes, two intracellular bacteria causing diseases in humans. We and others have demonstrated that this secretion system is also linked to the onset of long-term CD8(+) T cell-mediated protective immunity in mice. In the case of L. monocytogenes, expression of SecA2 inside the cytosol of infected cells correlates with the generation of CCL3-secreting memory CD8(+) T cells that are required for protection against secondary challenge with wild-type (wt) L. monocytogenes. Since the SecA2 ATPase is well conserved among Gram-positive pathogenic bacteria, we hypothesized that SecA2 itself bears evolutionarily conserved motifs recognized by cytosolic pattern recognition receptors, leading to signaling events promoting the differentiation of CCL3(+) memory CD8(+) T cells. To test this possibility, we generated a stable L. monocytogenes chromosomal mutant that expressed a SecA2 ATPase bearing a mutated nucleotide binding site (NBS). Similarly to a SecA2 deletion mutant, the NBS mutant exhibited rough colonies, a bacterial chaining phenotype, an impaired protein secretion profile, and in vivo virulence in comparison to wt L. monocytogenes. Importantly, mice immunized with the SecA2 NBS mutant were not protected against secondary infection with wt L. monocytogenes and did not develop CCL3(+) memory CD8(+) T cells. NBS mutant and wt SecA2 proteins were expressed to comparable extents by bacteria, suggesting that SecA2 itself is unlikely to promote the induction of these cells. Rather, one or several of the SecA2 substrate proteins released inside the cytosol of infected cells may be involved.
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Feltcher ME, Sullivan JT, Braunstein M. Protein export systems of Mycobacterium tuberculosis: novel targets for drug development? Future Microbiol 2011; 5:1581-97. [PMID: 21073315 DOI: 10.2217/fmb.10.112] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Protein export is essential in all bacteria and many bacterial pathogens depend on specialized protein export systems for virulence. In Mycobacterium tuberculosis, the etiological agent of the disease tuberculosis, the conserved general secretion (Sec) and twin-arginine translocation (Tat) pathways perform the bulk of protein export and are both essential. M. tuberculosis also has specialized export pathways that transport specific subsets of proteins. One such pathway is the accessory SecA2 system, which is important for M. tuberculosis virulence. There are also specialized ESX export systems that function in virulence (ESX-1) or essential physiologic processes (ESX-3). The increasing prevalence of drug-resistant M. tuberculosis strains makes the development of novel drugs for tuberculosis an urgent priority. In this article, we discuss our current understanding of the protein export systems of M. tuberculosis and consider the potential of these pathways to be novel targets for tuberculosis drugs.
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Affiliation(s)
- Meghan E Feltcher
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, CB # 7290, Chapel Hill, NC 27599, USA
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Oswald-Richter KA, Beachboard DC, Zhan X, Gaskill CF, Abraham S, Jenkins C, Culver DA, Drake W. Multiple mycobacterial antigens are targets of the adaptive immune response in pulmonary sarcoidosis. Respir Res 2010; 11:161. [PMID: 21092305 PMCID: PMC2999599 DOI: 10.1186/1465-9921-11-161] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 11/23/2010] [Indexed: 11/30/2022] Open
Abstract
Introduction Sarcoidosis is a multisystem granulomatous disease for which the association with mycobacteria continues to strengthen. It is hypothesized that a single, poorly degradable antigen is responsible for sarcoidosis pathogenesis. Several reports from independent groups support mycobacterial antigens having a role in sarcoidosis pathogenesis. To identify other microbial targets of the adaptive immune response, we tested the ability of CD4+ and CD8+ T cells to recognize multiple mycobacterial antigens. Methods Fifty-four subjects were enrolled in this study: 31 sarcoidosis patients, nine non-tuberculosis mycobacterial (NTM) infection controls, and 14 PPD- controls. Using flow cytometry, we assessed for Th1 immune responses to ESAT-6, katG, Ag85A, sodA, and HSP. Results Alveolar T-cells from twenty-two of the 31 sarcoidosis patients produced a CD4+ response to at least one of ESAT-6, katG, Ag85A, sodA, or HSP, compared to two of 14 PPD- controls (p = 0.0008) and five of nine NTM controls (p = 0.44), while eighteen of the 31 sarcoidosis subjects tested produced a CD8+ response to at least one of the mycobacterial antigens compared to two of 14 PPD- controls (p = 0.009) and three of nine NTM controls (0.26). Not only did the BAL-derived T cells respond to multiple virulence factors, but also to multiple, distinct epitopes within a given protein. The detection of proliferation upon stimulation with the mycobacterial virulence factors demonstrates that these responses are initiated by antigen specific recognition. Conclusions Together these results reveal that antigen-specific CD4+ and CD8+ T cells responses to multiple mycobacterial epitopes are present within sites of active sarcoidosis involvement, and that these antigen-specific responses are present at the time of diagnosis.
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Affiliation(s)
- Kyra A Oswald-Richter
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA.
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Kruh NA, Troudt J, Izzo A, Prenni J, Dobos KM. Portrait of a pathogen: the Mycobacterium tuberculosis proteome in vivo. PLoS One 2010; 5:e13938. [PMID: 21085642 PMCID: PMC2978697 DOI: 10.1371/journal.pone.0013938] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 10/07/2010] [Indexed: 12/23/2022] Open
Abstract
Background Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is a facultative intracellular pathogen that can persist within the host. The bacteria are thought to be in a state of reduced replication and metabolism as part of the chronic lung infection. Many in vitro studies have dissected the hypothesized environment within the infected lung, defining the bacterial response to pH, starvation and hypoxia. While these experiments have afforded great insight, the picture remains incomplete. The only way to study the combined effects of these environmental factors and the mycobacterial response is to study the bacterial response in vivo. Methodology/Principal Findings We used the guinea pig model of tuberculosis to examine the bacterial proteome during the early and chronic stages of disease. Lungs were harvested thirty and ninety days after aerosol challenge with Mtb, and analyzed by liquid chromatography-mass spectrometry. To date, in vivo proteomics of the tubercle bacillus has not been described and this work has generated the first large-scale shotgun proteomic data set, comprising over 500 unique protein identifications. Cell wall and cell wall processes, and intermediary metabolism and respiration were the two major functional classes of proteins represented in the infected lung. These classes of proteins displayed the greatest heterogeneity indicating important biological processes for establishment of a productive bacterial infection and its persistence. Proteins necessary for adaptation throughout infection, such as nitrate/nitrite reduction were found at both time points. The PE-PPE protein class, while not well characterized, represented the third most abundant category and showed the most consistent expression during the infection. Conclusions/Significance Cumulatively, the results of this work may provide the basis for rational drug design – identifying numerous Mtb proteins, from essential kinases to products involved in metal regulation and cell wall remodeling, all present throughout the course of infection.
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Affiliation(s)
- Nicole A. Kruh
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jolynn Troudt
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Angelo Izzo
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jessica Prenni
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, Colorado, United States of America
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Karen M. Dobos
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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Vizcaíno C, Restrepo-Montoya D, Rodríguez D, Niño LF, Ocampo M, Vanegas M, Reguero MT, Martínez NL, Patarroyo ME, Patarroyo MA. Computational prediction and experimental assessment of secreted/surface proteins from Mycobacterium tuberculosis H37Rv. PLoS Comput Biol 2010; 6:e1000824. [PMID: 20585611 PMCID: PMC2891697 DOI: 10.1371/journal.pcbi.1000824] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Accepted: 05/19/2010] [Indexed: 11/19/2022] Open
Abstract
The mycobacterial cell envelope has been implicated in the pathogenicity of tuberculosis and therefore has been a prime target for the identification and characterization of surface proteins with potential application in drug and vaccine development. In this study, the genome of Mycobacterium tuberculosis H37Rv was screened using Machine Learning tools that included feature-based predictors, general localizers and transmembrane topology predictors to identify proteins that are potentially secreted to the surface of M. tuberculosis, or to the extracellular milieu through different secretory pathways. The subcellular localization of a set of 8 hypothetically secreted/surface candidate proteins was experimentally assessed by cellular fractionation and immunoelectron microscopy (IEM) to determine the reliability of the computational methodology proposed here, using 4 secreted/surface proteins with experimental confirmation as positive controls and 2 cytoplasmic proteins as negative controls. Subcellular fractionation and IEM studies provided evidence that the candidate proteins Rv0403c, Rv3630, Rv1022, Rv0835, Rv0361 and Rv0178 are secreted either to the mycobacterial surface or to the extracellular milieu. Surface localization was also confirmed for the positive controls, whereas negative controls were located on the cytoplasm. Based on statistical learning methods, we obtained computational subcellular localization predictions that were experimentally assessed and allowed us to construct a computational protocol with experimental support that allowed us to identify a new set of secreted/surface proteins as potential vaccine candidates. Since the publication of the Mycobacterium tuberculosis genome in 1998, great expectations have emerged regarding speeding up the process of developing vaccines against tuberculosis. Our group has been focused on identifying molecules localized on the mycobacterial surface that could act as ligands facilitating this pathogen's entry into host cells. Immune responses exerted against these proteins might block receptor-ligand interactions, thus hampering mycobacterial invasion. Since protein fragments involved in these interactions might serve as vaccine candidates and, taking into account that a relatively small number of mycobacterial surface proteins have been experimentally identified to date due to the inherent difficulty of proteomics studies for characterizing surface proteins, in this study, we used Machine Learning-based tools available on the World Wide Web to obtain accurate predictions of surface and secreted proteins from this pathogen and found experimental support of such predictions for a group of candidate proteins selected based on novel criteria.
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Affiliation(s)
- Carolina Vizcaíno
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- Microbiology postgraduate program, Universidad Nacional de Colombia, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Daniel Restrepo-Montoya
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
- Intelligent Systems Research Laboratory – LISI, Universidad Nacional de Colombia, Bogotá, Colombia
- Research Group on Combinatorial Algorithms – ALGOS-UN, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Diana Rodríguez
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Luis F. Niño
- Intelligent Systems Research Laboratory – LISI, Universidad Nacional de Colombia, Bogotá, Colombia
- Research Group on Combinatorial Algorithms – ALGOS-UN, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Marisol Ocampo
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Magnolia Vanegas
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - María T. Reguero
- Instituto de Biotecnología – IBUN, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Nora L. Martínez
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Manuel E. Patarroyo
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Manuel A. Patarroyo
- Fundación Instituto de Inmunología de Colombia – FIDIC, Bogotá, Colombia
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
- * E-mail:
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Miller JL, Velmurugan K, Cowan MJ, Briken V. The type I NADH dehydrogenase of Mycobacterium tuberculosis counters phagosomal NOX2 activity to inhibit TNF-alpha-mediated host cell apoptosis. PLoS Pathog 2010; 6:e1000864. [PMID: 20421951 PMCID: PMC2858756 DOI: 10.1371/journal.ppat.1000864] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 03/18/2010] [Indexed: 01/01/2023] Open
Abstract
The capacity of infected cells to undergo apoptosis upon insult with a pathogen is an ancient innate immune defense mechanism. Consequently, the ability of persisting, intracellular pathogens such as the human pathogen Mycobacterium tuberculosis (Mtb) to inhibit infection-induced apoptosis of macrophages is important for virulence. The nuoG gene of Mtb, which encodes the NuoG subunit of the type I NADH dehydrogenase, NDH-1, is important in Mtb-mediated inhibition of host macrophage apoptosis, but the molecular mechanism of this host pathogen interaction remains elusive. Here we show that the apoptogenic phenotype of MtbDeltanuoG was significantly reduced in human macrophages treated with caspase-3 and -8 inhibitors, TNF-alpha-neutralizing antibodies, and also after infection of murine TNF(-/-) macrophages. Interestingly, incubation of macrophages with inhibitors of reactive oxygen species (ROS) reduced not only the apoptosis induced by the nuoG mutant, but also its capacity to increase macrophage TNF-alpha secretion. The MtbDeltanuoG phagosomes showed increased ROS levels compared to Mtb phagosomes in primary murine and human alveolar macrophages. The increase in MtbDeltanuoG induced ROS and apoptosis was abolished in NOX-2 deficient (gp91(-/-)) macrophages. These results suggest that Mtb, via a NuoG-dependent mechanism, can neutralize NOX2-derived ROS in order to inhibit TNF-alpha-mediated host cell apoptosis. Consistently, an Mtb mutant deficient in secreted catalase induced increases in phagosomal ROS and host cell apoptosis, both of which were dependent upon macrophage NOX-2 activity. In conclusion, these results serendipitously reveal a novel connection between NOX2 activity, phagosomal ROS, and TNF-alpha signaling during infection-induced apoptosis in macrophages. Furthermore, our study reveals a novel function of NOX2 activity in innate immunity beyond the initial respiratory burst, which is the sensing of persistent intracellular pathogens and subsequent induction of host cell apoptosis as a second line of defense.
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Affiliation(s)
- Jessica L. Miller
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
- Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, United States of America
| | - Kamalakannan Velmurugan
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Mark J. Cowan
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Maryland, Baltimore, Maryland, United States of America
| | - Volker Briken
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
- Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
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Goudenège D, Avner S, Lucchetti-Miganeh C, Barloy-Hubler F. CoBaltDB: Complete bacterial and archaeal orfeomes subcellular localization database and associated resources. BMC Microbiol 2010; 10:88. [PMID: 20331850 PMCID: PMC2850352 DOI: 10.1186/1471-2180-10-88] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 03/23/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The functions of proteins are strongly related to their localization in cell compartments (for example the cytoplasm or membranes) but the experimental determination of the sub-cellular localization of proteomes is laborious and expensive. A fast and low-cost alternative approach is in silico prediction, based on features of the protein primary sequences. However, biologists are confronted with a very large number of computational tools that use different methods that address various localization features with diverse specificities and sensitivities. As a result, exploiting these computer resources to predict protein localization accurately involves querying all tools and comparing every prediction output; this is a painstaking task. Therefore, we developed a comprehensive database, called CoBaltDB, that gathers all prediction outputs concerning complete prokaryotic proteomes. DESCRIPTION The current version of CoBaltDB integrates the results of 43 localization predictors for 784 complete bacterial and archaeal proteomes (2.548.292 proteins in total). CoBaltDB supplies a simple user-friendly interface for retrieving and exploring relevant information about predicted features (such as signal peptide cleavage sites and transmembrane segments). Data are organized into three work-sets ("specialized tools", "meta-tools" and "additional tools"). The database can be queried using the organism name, a locus tag or a list of locus tags and may be browsed using numerous graphical and text displays. CONCLUSIONS With its new functionalities, CoBaltDB is a novel powerful platform that provides easy access to the results of multiple localization tools and support for predicting prokaryotic protein localizations with higher confidence than previously possible. CoBaltDB is available at http://www.umr6026.univ-rennes1.fr/english/home/research/basic/software/cobalten.
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Affiliation(s)
- David Goudenège
- CNRS UMR 6026, ICM, Equipe B@SIC, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes, France
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125
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A proteomic view of cell physiology and virulence of Staphylococcus aureus. Int J Med Microbiol 2010; 300:76-87. [DOI: 10.1016/j.ijmm.2009.10.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Yuan J, Zweers JC, van Dijl JM, Dalbey RE. Protein transport across and into cell membranes in bacteria and archaea. Cell Mol Life Sci 2010; 67:179-99. [PMID: 19823765 PMCID: PMC11115550 DOI: 10.1007/s00018-009-0160-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/13/2009] [Accepted: 09/21/2009] [Indexed: 12/21/2022]
Abstract
In the three domains of life, the Sec, YidC/Oxa1, and Tat translocases play important roles in protein translocation across membranes and membrane protein insertion. While extensive studies have been performed on the endoplasmic reticular and Escherichia coli systems, far fewer studies have been done on archaea, other Gram-negative bacteria, and Gram-positive bacteria. Interestingly, work carried out to date has shown that there are differences in the protein transport systems in terms of the number of translocase components and, in some cases, the translocation mechanisms and energy sources that drive translocation. In this review, we will describe the different systems employed to translocate and insert proteins across or into the cytoplasmic membrane of archaea and bacteria.
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Affiliation(s)
- Jijun Yuan
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
| | - Jessica C. Zweers
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, 30001, 9700 RB Groningen, The Netherlands
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, 30001, 9700 RB Groningen, The Netherlands
| | - Ross E. Dalbey
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
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Bitter W, Houben ENG, Bottai D, Brodin P, Brown EJ, Cox JS, Derbyshire K, Fortune SM, Gao LY, Liu J, Gey van Pittius NC, Pym AS, Rubin EJ, Sherman DR, Cole ST, Brosch R. Systematic genetic nomenclature for type VII secretion systems. PLoS Pathog 2009; 5:e1000507. [PMID: 19876390 PMCID: PMC2763215 DOI: 10.1371/journal.ppat.1000507] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Wilbert Bitter
- VU University Medical Centre, Amsterdam, The Netherlands
- * E-mail: (WB); (RB)
| | | | - Daria Bottai
- Dipartimento di Patologia Sperimentale, Biotecnologie Mediche, Infettivologia ed Epidemiologia, University of Pisa, Pisa, Italy
| | | | - Eric J. Brown
- Department of Microbial Pathogenesis, Genentech Inc., San Francisco, California, United States of America
| | - Jeffery S. Cox
- Department of Microbiology and Immunology, University of California, San Francisco, California, United States of America
| | - Keith Derbyshire
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Sarah M. Fortune
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Lian-Yong Gao
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Jun Liu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | | | - Alexander S. Pym
- Unit for Clinical and Biomedical TB Research, South African MRC, Durban, South Africa
| | - Eric J. Rubin
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - David R. Sherman
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | | | - Roland Brosch
- Institut Pasteur, Integrated Mycobacterial Pathogenomics, Paris, France
- * E-mail: (WB); (RB)
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Recombinant pro-apoptotic Mycobacterium tuberculosis generates CD8+ T cell responses against human immunodeficiency virus type 1 Env and M. tuberculosis in neonatal mice. Vaccine 2009; 28:152-61. [PMID: 19808028 DOI: 10.1016/j.vaccine.2009.09.087] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 07/29/2009] [Accepted: 09/23/2009] [Indexed: 12/18/2022]
Abstract
Mycobacterium bovis BCG is an attractive vaccine vector against breast milk HIV transmission because it elicits Th1-type responses in newborns. However, BCG causes disease in HIV-infected infants. Genetically attenuated Mycobacterium tuberculosis (Mtb) mutants represent a safer alternative for immunocompromised populations. In the current study, we compared the immunogenicity in mice of three different recombinant attenuated Mtb strains expressing an HIV envelope (Env) antigen construct. Two of these strains (DeltalysA DeltapanCD Mtb and DeltaRD1 DeltapanCD Mtb) failed to induce significant levels of HIV Env-specific CD8(+) T cell responses. In striking contrast, an HIV-1 Env-expressing attenuated DeltalysA Mtb containing a deletion in secA2, which encodes a virulence-related secretion system involved in evading adaptive immunity, generated consistently measurable Env-specific CD8(+) T cell responses that were significantly greater than those observed after immunization with BCG expressing HIV Env. Similarly, another strain of DeltalysA DeltasecA2 Mtb expressing SIV Gag induced Gag- and Mtb-specific CD8(+) T cells producing perforin or IFNgamma, and Gag-specific CD4(+) T cells producing IFNgamma within 3 weeks after immunization in adult mice; in addition, IFNgamma-producing Gag-specific CD8(+) T cells and Mtb-specific CD4(+) T cells were observed in neonatal mice within 1 week of immunization. We conclude that DeltalysA DeltasecA2 Mtb is a promising vaccine platform to construct a safe combination HIV-TB vaccine for use in neonates.
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Shin AR, Kim HJ, Cho SN, Collins MT, Manning EJB, Naser SA, Shin SJ. Identification of seroreactive proteins in the culture filtrate antigen of Mycobacterium avium ssp. paratuberculosis human isolates to sera from Crohn's disease patients. ACTA ACUST UNITED AC 2009; 58:128-37. [PMID: 19878316 DOI: 10.1111/j.1574-695x.2009.00617.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The etiology of Crohn's disease (CD) is unresolved, but it is likely that an interplay of host genetic factors and environmental triggers is relevant. Mycobacterium paratuberculosis (MAP) has been focused upon as one of these triggers because it causes a similar chronic inflammatory bowel disease in animals. However, the differences among MAP antigens isolated from humans (H-MAP) and cattle (B-MAP) have not been well characterized. In this study, culture filtrate (CF) proteins from MAP isolates were tested with sera from CD patients and healthy controls in enzyme-linked immunosorbent assay (ELISA). Antibody produced by seven CD patients reacted differently according to the antigen source: strong reactivity was seen to H-MAP CF, but not to B-MAP CF. Six proteins, ModD, PepA, transaldolase, EchA9, MAP2120c, and MAP2950c, in H-MAP CF reacting specifically with CD patient sera were identified by liquid chromatography-electrospray ionization-MS. Bioinformatic analysis revealed that ModD and PepA were the same proteins reacting with sera from cattle infected with MAP. The elevated antibody responses of CD patients to rModD and rPepA were confirmed by ELISA (P<0.001). These results support previous studies showing ModD and PepA as key antigens for the diagnosis of MAP infections. The study also identified additional proteins potentially useful in the design of assays for human MAP infections.
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Affiliation(s)
- A-Rum Shin
- Department of Microbiology, Research Institute for Medical Sciences, College of Medicine, Chungnam National University, Daejeon, South Korea
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Abstract
Bacillus anthracis is a Gram-positive, spore-forming bacterium representing the etiological cause of anthrax, a rare lethal disease of animals and humans. Development of anthrax countermeasures has gained increasing attention owing to the potential use of B. anthracis spores as a bioterror weapon. The various forms of infection by B. anthracis are characterized both by toxemia and septicemia, both of which are the result of spore entry into the host followed by their germination into rapidly multiplying, toxin-producing bacilli. Following the publication of the bacterial genome, proteomic studies were carried out to determine the protein composition of the spore and identify exposed vegetative (membrane-located or secreted) proteins. These studies included comparison of strains differing in their virulence, cultured under different conditions and, in some cases, were complemented by serological inspection, which addressed expression during infection of proteomically identified proteins and their immunogenicity. The proteomic approach emerged as a valuable strategy for the generation of a pool of potential B. anthracis protein targets for further evaluation in detection, diagnostics, therapy and prophylaxis, and contributed to the elucidation of some aspects of the pathogenesis of the disease.
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Affiliation(s)
- Theodor Chitlaru
- Department of Biochemistry & Molecular Genetics, Israel Institute for Biological Research, PO Box 19, Ness-Ziona 74100, Israel
| | - Avigdor Shafferman
- Department of Biochemistry & Molecular Genetics, Israel Institute for Biological Research, PO Box 19, Ness-Ziona 74100, Israel
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Abstract
Infections with Mycobacterium tuberculosis remain a major cause of disease and death in humans. Among the factors that contribute to M. tuberculosis's success as a pathogen is its ability to withstand potentially bactericidal host defences and to resist elimination by an activated immune system. This resistance to killing by the host is in part due to the low permeability of the mycobacterial cell envelope for many toxic molecules. In addition, it depends upon the detoxification of reactive oxygen and reactive nitrogen molecules produced by the host, the repair of the damage these molecules cause and maintenance of a neutral intrabacterial pH within acidic environments. The latter three mechanisms are the focus of this review.
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Affiliation(s)
- Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA.
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Development of a murine mycobacterial growth inhibition assay for evaluating vaccines against Mycobacterium tuberculosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2009; 16:1025-32. [PMID: 19458207 DOI: 10.1128/cvi.00067-09] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The development and characterization of new tuberculosis (TB) vaccines has been impeded by the lack of reproducible and reliable in vitro assays for measuring vaccine activity. In this study, we developed a murine in vitro mycobacterial growth inhibition assay for evaluating TB vaccines that directly assesses the capacity of immune splenocytes to control the growth of Mycobacterium tuberculosis within infected macrophages. Using this in vitro assay, protective immune responses induced by immunization with five different types of TB vaccine preparations (Mycobacterium bovis BCG, an attenuated M. tuberculosis mutant strain, a DNA vaccine, a modified vaccinia virus strain Ankara [MVA] construct expressing four TB antigens, and a TB fusion protein formulated in adjuvant) can be detected. Importantly, the levels of vaccine-induced mycobacterial growth-inhibitory responses seen in vitro after 1 week of coculture correlated with the protective immune responses detected in vivo at 28 days postchallenge in a mouse model of pulmonary tuberculosis. In addition, similar patterns of cytokine expression were evoked at day 7 of the in vitro culture by immune splenocytes taken from animals immunized with the different TB vaccines. Among the consistently upregulated cytokines detected in the immune cocultures are gamma interferon, growth differentiation factor 15, interleukin-21 (IL-21), IL-27, and tumor necrosis factor alpha. Overall, we have developed an in vitro functional assay that may be useful for screening and comparing new TB vaccine preparations, investigating vaccine-induced protective mechanisms, and assessing manufacturing issues, including product potency and stability.
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Sadagopal S, Braunstein M, Hager CC, Wei J, Daniel AK, Bochan MR, Crozier I, Smith NE, Gates HO, Barnett L, Van Kaer L, Price JO, Blackwell TS, Kalams SA, Kernodle DS. Reducing the activity and secretion of microbial antioxidants enhances the immunogenicity of BCG. PLoS One 2009; 4:e5531. [PMID: 19436730 PMCID: PMC2677452 DOI: 10.1371/journal.pone.0005531] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 04/17/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In early clinical studies, the live tuberculosis vaccine Mycobacterium bovis BCG exhibited 80% protective efficacy against pulmonary tuberculosis (TB). Although BCG still exhibits reliable protection against TB meningitis and miliary TB in early childhood it has become less reliable in protecting against pulmonary TB. During decades of in vitro cultivation BCG not only lost some genes due to deletions of regions of the chromosome but also underwent gene duplication and other mutations resulting in increased antioxidant production. METHODOLOGY/PRINCIPAL FINDINGS To determine whether microbial antioxidants influence vaccine immunogenicity, we eliminated duplicated alleles encoding the oxidative stress sigma factor SigH in BCG Tice and reduced the activity and secretion of iron co-factored superoxide dismutase. We then used assays of gene expression and flow cytometry with intracellular cytokine staining to compare BCG-specific immune responses in mice after vaccination with BCG Tice or the modified BCG vaccine. Compared to BCG, the modified vaccine induced greater IL-12p40, RANTES, and IL-21 mRNA in the spleens of mice at three days post-immunization, more cytokine-producing CD8+ lymphocytes at the peak of the primary immune response, and more IL-2-producing CD4+ lymphocytes during the memory phase. The modified vaccine also induced stronger secondary CD4+ lymphocyte responses and greater clearance of challenge bacilli. CONCLUSIONS/SIGNIFICANCE We conclude that antioxidants produced by BCG suppress host immune responses. These findings challenge the hypothesis that the failure of extensively cultivated BCG vaccines to prevent pulmonary tuberculosis is due to over-attenuation and suggest instead a new model in which BCG evolved to produce more immunity-suppressing antioxidants. By targeting these antioxidants it may be possible to restore BCG's ability to protect against pulmonary TB.
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Affiliation(s)
- Shanmugalakshmi Sadagopal
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Miriam Braunstein
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Cynthia C. Hager
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jie Wei
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Alexandria K. Daniel
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Markian R. Bochan
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Ian Crozier
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Nathaniel E. Smith
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Hiriam O. Gates
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Louise Barnett
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Luc Van Kaer
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - James O. Price
- Department of Veterans Affairs Medical Center, Nashville, Tennessee, United States of America
| | - Timothy S. Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Veterans Affairs Medical Center, Nashville, Tennessee, United States of America
| | - Spyros A. Kalams
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Douglas S. Kernodle
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Veterans Affairs Medical Center, Nashville, Tennessee, United States of America
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Restrepo-Montoya D, Vizcaíno C, Niño LF, Ocampo M, Patarroyo ME, Patarroyo MA. Validating subcellular localization prediction tools with mycobacterial proteins. BMC Bioinformatics 2009; 10:134. [PMID: 19422713 PMCID: PMC2685389 DOI: 10.1186/1471-2105-10-134] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 05/07/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The computational prediction of mycobacterial proteins' subcellular localization is of key importance for proteome annotation and for the identification of new drug targets and vaccine candidates. Several subcellular localization classifiers have been developed over the past few years, which have comprised both general localization and feature-based classifiers. Here, we have validated the ability of different bioinformatics approaches, through the use of SignalP 2.0, TatP 1.0, LipoP 1.0, Phobius, PA-SUB 2.5, PSORTb v.2.0.4 and Gpos-PLoc, to predict secreted bacterial proteins. These computational tools were compared in terms of sensitivity, specificity and Matthew's correlation coefficient (MCC) using a set of mycobacterial proteins having less than 40% identity, none of which are included in the training data sets of the validated tools and whose subcellular localization have been experimentally confirmed. These proteins belong to the TBpred training data set, a computational tool specifically designed to predict mycobacterial proteins. RESULTS A final validation set of 272 mycobacterial proteins was obtained from the initial set of 852 mycobacterial proteins. According to the results of the validation metrics, all tools presented specificity above 0.90, while dispersion sensitivity and MCC values were above 0.22. PA-SUB 2.5 presented the highest values; however, these results might be biased due to the methodology used by this tool. PSORTb v.2.0.4 left 56 proteins out of the classification, while Gpos-PLoc left just one protein out. CONCLUSION Both subcellular localization approaches had high predictive specificity and high recognition of true negatives for the tested data set. Among those tools whose predictions are not based on homology searches against SWISS-PROT, Gpos-PLoc was the general localization tool with the best predictive performance, while SignalP 2.0 was the best tool among the ones using a feature-based approach. Even though PA-SUB 2.5 presented the highest metrics, it should be taken into account that this tool was trained using all proteins reported in SWISS-PROT, which includes the protein set tested in this study, either as a BLAST search or as a training model.
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Affiliation(s)
- Daniel Restrepo-Montoya
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No, 26-20 Bogotá DC, Colombia.
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Molecular dissection of the secA2 locus of group B Streptococcus reveals that glycosylation of the Srr1 LPXTG protein is required for full virulence. J Bacteriol 2009; 191:4195-206. [PMID: 19395494 DOI: 10.1128/jb.01673-08] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In streptococci, the secA2 locus includes genes encoding the following: (i) the accessory Sec components (SecA2, SecY2, and at least three accessory secretion proteins), (ii) two essential glycosyltranferases (GTs) (GtfA and GtfB), (iii) a variable number of dispensable additional GTs, and (iv) a secreted serine-rich LPXTG protein which is glycosylated in the cytoplasm and transported to the cell surface by this accessory Sec system. The secA2 locus of Streptococcus agalactiae strain NEM316 is structurally related to those found in other streptococci and encodes the serine-rich surface protein Srr1. We demonstrated that expression of Srr1 but not that of the SecA2 components and the associated GTs is regulated by the standalone transcriptional regulator Rga. Srr1 is synthesized as a glycosylated precursor, secreted by the SecA2 system, and anchored to the cell wall by the housekeeping sortase A. Srr1 was localized preferentially at the old poles. GtfA and/or GtfB, but not the six additional GTs, is essential for the production of Srr1. These GTs are involved in the attachment of GlcNac and sialic acid to Srr1. Full glycosylation of Srr1 is associated with the cell surface display of a protein that is more resistant to proteolytic attack. Srr1 contributes to bacterial adherence to human epithelial cell lines and virulence in a neonatal rat model. The extent of Srr1 glycosylation by GtfC to -H modulates bacterial adherence and virulence.
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136
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Abstract
The accessory Sec system of Streptococcus gordonii is essential for transport of the glycoprotein GspB to the bacterial cell surface. A key component of this dedicated transport system is SecA2. The SecA2 proteins of streptococci and staphylococci are paralogues of SecA and are presumed to have an analogous role in protein transport, but they may be specifically adapted for the transport of large, serine-rich glycoproteins. We used a combination of genetic and biochemical methods to assess whether the S. gordonii SecA2 functions similarly to SecA. Although mutational analyses demonstrated that conserved amino acids are essential for the function of SecA2, replacing such residues in one of two nucleotide binding folds had only minor effects on SecA2 function. SecA2-mediated transport is highly sensitive to azide, as is SecA-mediated transport. Comparison of the S. gordonii SecA and SecA2 proteins in vitro revealed that SecA2 can hydrolyze ATP at a rate similar to that of SecA and is comparably sensitive to azide but that the biochemical properties of these enzymes are subtly different. That is, SecA2 has a lower solubility in aqueous solutions and requires higher Mg(2+) concentrations for maximal activity. In spite of the high degree of similarity between the S. gordonii paralogues, analysis of SecA-SecA2 chimeras indicates that the domains are not readily interchangeable. This suggests that specific, unique contacts between SecA2 and other components of the accessory Sec system may preclude cross-functioning with the canonical Sec system.
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137
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Desvaux M, Hébraud M, Talon R, Henderson IR. Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue. Trends Microbiol 2009; 17:139-45. [PMID: 19299134 DOI: 10.1016/j.tim.2009.01.004] [Citation(s) in RCA: 261] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 12/17/2008] [Accepted: 01/16/2009] [Indexed: 12/24/2022]
Abstract
Extracellular proteins are a subject of intense interest because of their essential roles in bacterial lifestyles. However, several terms related to secretion are used confusingly in the literature, and this is a topical issue in genomics and proteomics. Defining a secreted protein as actively translocated via a secretion system, here, we put into perspective that homologous translocation systems can result in radically different subcellular localizations of a secreted protein. We propose using standardized nomenclature for secretion systems from type I to type VIII for Gram-negative bacteria only, whereas the terms 'Sec' (secretion), 'Tat' (twin-arginine translocation), 'FEA' (flagella export apparatus), 'FPE' (fimbrilin-protein exporter), 'holin' (hole forming) and 'Wss' (WXG100 secretion system) should be applied to translocation systems across the cytoplasmic membrane of both Gram-positive and Gram-negative bacteria. Finally, we discuss why the term 'exoproteome' should be favoured over 'secretome' when describing the subset of proteins present in the extracellular milieu.
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Affiliation(s)
- Mickaël Desvaux
- INRA (Institut National de la Recherche Agronomique), UR454 Microbiologie, Centre de Recherche Clermont-Ferrand, F-63122 Saint-Genès Champanelle, France.
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Rigel NW, Gibbons HS, McCann JR, McDonough JA, Kurtz S, Braunstein M. The Accessory SecA2 System of Mycobacteria Requires ATP Binding and the Canonical SecA1. J Biol Chem 2009; 284:9927-36. [PMID: 19240020 DOI: 10.1074/jbc.m900325200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In bacteria, the majority of exported proteins are transported by the general Sec pathway from their site of synthesis in the cytoplasm across the cytoplasmic membrane. The essential SecA ATPase powers this Sec-mediated export. Mycobacteria possess two nonredundant SecA homologs: SecA1 and SecA2. In pathogenic Mycobacterium tuberculosis and the nonpathogenic model mycobacterium Mycobacterium smegmatis, SecA1 is essential for protein export and is the "housekeeping" SecA, whereas SecA2 is an accessory SecA that exports a specific subset of proteins. In M. tuberculosis the accessory SecA2 pathway plays a role in virulence. In this study, we uncovered basic properties of the mycobacterial SecA2 protein and its pathway for exporting select proteins. By constructing secA2 mutant alleles that encode proteins defective in ATP binding, we showed that ATP binding is required for SecA2 function. SecA2 mutant proteins unable to bind ATP were nonfunctional and dominant negative. By evaluating the subcellular distribution of each SecA, SecA1 was shown to be equally divided between cytosolic and cell envelope fractions, whereas SecA2 was predominantly localized to the cytosol. Finally, we showed that the canonical SecA1 has a role in the process of SecA2-dependent export. The accessory SecA2 export system is important to the physiology and virulence of mycobacteria. These studies help establish the mechanism of this new type of specialized protein export pathway.
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Affiliation(s)
- Nathan W Rigel
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7290, USA
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139
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The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates. Proc Natl Acad Sci U S A 2009; 106:4414-8. [PMID: 19237572 DOI: 10.1073/pnas.0810126106] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium tuberculosis has evolved a number of strategies to survive within the hostile environment of host phagocytes. Reactive nitrogen and oxygen intermediates (RNI and ROI) are among the most effective antimycobacterial molecules generated by the host during infection. Lsr2 is a M. tuberculosis protein with histone-like features, including the ability to regulate a variety of transcriptional responses in mycobacteria. Here we demonstrate that Lsr2 protects mycobacteria against ROI in vitro and during macrophage infection. Furthermore, using macrophages derived from NOS(-/-) and Phox(-/-) mice, we demonstrate that Lsr2 is important in protecting against ROI but not RNI. The protection provided by Lsr2 protein is not the result of its ability to either bind iron or scavenge hydroxyl radicals. Instead, electron microscopy and DNA-binding studies suggest that Lsr2 shields DNA from reactive intermediates by binding bacterial DNA and physically protecting it. Thus, Lsr2 appears to be a unique protein with both histone-like properties and protective features that may be central to M. tuberculosis pathogenesis. In addition, evidence indicates that lsr2 is an essential gene in M. tuberculosis. Because of its essentiality, Lsr2 may represent an excellent candidate as a drug target.
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Schulte C, Arenskötter M, Berekaa MM, Arenskötter Q, Priefert H, Steinbüchel A. Possible involvement of an extracellular superoxide dismutase (SodA) as a radical scavenger in poly(cis-1,4-isoprene) degradation. Appl Environ Microbiol 2008; 74:7643-53. [PMID: 18952871 PMCID: PMC2607186 DOI: 10.1128/aem.01490-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 10/20/2008] [Indexed: 11/20/2022] Open
Abstract
Gordonia westfalica Kb1 and Gordonia polyisoprenivorans VH2 induce the formation of an extracellular superoxide dismutase (SOD) during poly(cis-1,4-isoprene) degradation. To investigate the function of this enzyme in G. polyisoprenivorans VH2, the sodA gene was disrupted. The mutants exhibited reduced growth in liquid mineral salt media containing poly(cis-1,4-isoprene) as the sole carbon and energy source, and no SOD activity was detectable in the supernatants of the cultures. Growth experiments revealed that SodA activity is required for optimal growth on poly(cis-1,4-isoprene), whereas this enzyme has no effect on aerobic growth in the presence of water-soluble substrates like succinate, acetate, and propionate. This was detected by activity staining, and proof of expression was by antibody detection of SOD. When SodA from G. westfalica Kb1 was heterologously expressed in the sodA sodB double mutant Escherichia coli QC779, the recombinant mutant exhibited increased resistance to paraquat, thereby indicating the functionality of the G. westfalica Kb1 SodA and indirectly protection of G. westfalica cells by SodA from oxidative damage. Both sodA from G. polyisoprenivorans VH2 and sodA from G. westfalica Kb1 coded for polypeptides comprising 209 amino acids and having approximately 90% and 70% identical amino acids, respectively, to the SodA from Mycobacterium smegmatis strain MC(2) 155 and Micrococcus luteus NCTC 2665. As revealed by activity staining experiments with the wild type and the disruption mutant of G. polyisoprenivorans, this bacterium harbors only one active SOD belonging to the manganese family. The N-terminal sequences of the extracellular SodA proteins of both Gordonia species showed no evidence of leader peptides for the mature proteins, like the intracellular SodA protein of G. polyisoprenivorans VH2, which was purified under native conditions from the cells. In G. westfalica Kb1 and G. polyisoprenivorans VH2, SodA probably provides protection against reactive oxygen intermediates which occur during degradation of poly(cis-1,4-isoprene).
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Affiliation(s)
- Carina Schulte
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Correnstrasse 3, D-48149 Münster, Germany
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Chen M, Divangahi M, Gan H, Shin DSJ, Hong S, Lee DM, Serhan CN, Behar SM, Remold HG. Lipid mediators in innate immunity against tuberculosis: opposing roles of PGE2 and LXA4 in the induction of macrophage death. ACTA ACUST UNITED AC 2008; 205:2791-801. [PMID: 18955568 PMCID: PMC2585850 DOI: 10.1084/jem.20080767] [Citation(s) in RCA: 270] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Virulent Mycobacterium tuberculosis (Mtb) induces a maladaptive cytolytic death modality, necrosis, which is advantageous for the pathogen. We report that necrosis of macrophages infected with the virulent Mtb strains H37Rv and Erdmann depends on predominant LXA(4) production that is part of the antiinflammatory and inflammation-resolving action induced by Mtb. Infection of macrophages with the avirulent H37Ra triggers production of high levels of the prostanoid PGE(2), which promotes protection against mitochondrial inner membrane perturbation and necrosis. In contrast to H37Ra infection, PGE(2) production is significantly reduced in H37Rv-infected macrophages. PGE(2) acts by engaging the PGE(2) receptor EP2, which induces cyclic AMP production and protein kinase A activation. To verify a role for PGE(2) in control of bacterial growth, we show that infection of prostaglandin E synthase (PGES)(-/-) macrophages in vitro with H37Rv resulted in significantly higher bacterial burden compared with wild-type macrophages. More importantly, PGES(-/-) mice harbor significantly higher Mtb lung burden 5 wk after low-dose aerosol infection with virulent Mtb. These in vitro and in vivo data indicate that PGE(2) plays a critical role in inhibition of Mtb replication.
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Affiliation(s)
- Minjian Chen
- Department of Medicine, Division of Rheumatology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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142
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Briken V, Miller JL. Living on the edge: inhibition of host cell apoptosis by Mycobacterium tuberculosis. Future Microbiol 2008; 3:415-22. [PMID: 18651813 DOI: 10.2217/17460913.3.4.415] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Tuberculosis is a human disease of global importance caused by infection with Mycobacterium tuberculosis. Thus, an estimated one-third of the world's population is latently infected; there are 2-3 million annual deaths and an increasing amount of multidrug-resistant and extensive drug-resistant tuberculosis cases. M. tuberculosis is a highly adapted human pathogen that has evolved to employ multiple strategies in its attempt to avoid an efficient host immune response. The induction of host cell death is an ancient immune defense strategy that is conserved throughout the animal and plant kingdoms. Here we review the current status of the research involving interaction of mycobacteria with host cells, regarding the induction of host cell death by apoptosis. We conclude that virulent strains of M. tuberculosis employ several strategies to avoid the induction of macrophage cell death, and success in this process is clearly important for bacterial virulence. The molecular mechanisms of host cell apoptosis inhibition are little understood, but the recent identification of anti-apoptosis genes in the genome of M. tuberculosis has provided the tools necessary to investigate the details of this host-pathogen interaction. The results of these future studies may prove useful for the development of new drug targets and/or vaccine candidates.
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Affiliation(s)
- Volker Briken
- Department of Cell Biology & Molecular Genetics and, The Marlyand Pathogen Research Institute, University of Maryland, College Park, MD 20742, USA.
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143
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Abstract
The export of proteins from their site of synthesis in the cytoplasm across the inner membrane is an important aspect of bacterial physiology. Because the location of extracytoplasmic proteins is ideal for host-pathogen interactions, protein export is also important to bacterial virulence. In bacteria, there are conserved protein export systems that are responsible for the majority of protein export: the general secretion (Sec) pathway and the twin-arginine translocation pathway. In some bacteria, there are also specialized export systems dedicated to exporting specific subsets of proteins. In this review, we discuss a specialized export system that exists in some Gram-positive bacteria and mycobacteria - the accessory Sec system. The common element to the accessory Sec system is an accessory SecA protein called SecA2. Here we present our current understanding of accessory Sec systems in Streptococcus gordonii, Streptococcus parasanguinis, Mycobacterium smegmatis, Mycobacterium tuberculosis and Listeria monocytogenes, making an effort to highlight apparent similarities and differences between the systems. We also review the data showing that accessory Sec systems can contribute to bacterial virulence.
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Affiliation(s)
- Nathan W Rigel
- Department of Microbiology and Immunology, University of North Carolina, School of Medicine, Chapel Hill, NC 27599-7290, USA
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144
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West NP, Wozniak TM, Valenzuela J, Feng CG, Sher A, Ribeiro JMC, Britton WJ. Immunological diversity within a family of cutinase-like proteins of Mycobacterium tuberculosis. Vaccine 2008; 26:3853-9. [PMID: 18565629 DOI: 10.1016/j.vaccine.2008.05.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 04/23/2008] [Accepted: 05/07/2008] [Indexed: 11/24/2022]
Abstract
Secreted proteins of Mycobacterium tuberculosis play key roles in the assembly of the mycobacterial cell wall, with many being major targets of the host immune response. To date, meaningful characterization of a significant proportion of this important group of proteins is lacking. Among the group of putatively secreted proteins of M. tuberculosis are 7 cutinase-like proteins (CLP), not previously characterized in terms of their immunogenicity or vaccine protective efficacy. Although the CLP vary in the degree of homology with one another, they all share a similar active catalytic triad, closely homologous to that of the cutinase of Fusarium solani. By construction of DNA vaccines of all 7 CLP, and expression and purification of soluble, recombinant CLP, this study addresses the immunological responses to these proteins. Clp1, 2, 3 and 6 were found to elicit significant IFN-gamma secretion in DNA immunized mice, with the antigens also demonstrating specificity in terms of CLP-generated T cell IFN-gamma release, with minimal cross reactivity of humoral responses. Finally, following delivery of DNA vaccines, Clp1, 2 and 6, conferred a moderate yet reproducible and significant level of protection in a murine aerosol model of M. tuberculosis infection.
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Affiliation(s)
- Nicholas P West
- Mycobacterial Research Program, Centenary Institute of Cancer Medicine and Cell Biology. Locked Bag 6, Newtown, NSW 2042, Australia.
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145
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ATPase activity of Mycobacterium tuberculosis SecA1 and SecA2 proteins and its importance for SecA2 function in macrophages. J Bacteriol 2008; 190:4880-7. [PMID: 18487341 DOI: 10.1128/jb.00412-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Sec-dependent translocation pathway that involves the essential SecA protein and the membrane-bound SecYEG translocon is used to export many proteins across the cytoplasmic membrane. Recently, several pathogenic bacteria, including Mycobacterium tuberculosis, were shown to possess two SecA homologs, SecA1 and SecA2. SecA1 is essential for general protein export. SecA2 is specific for a subset of exported proteins and is important for M. tuberculosis virulence. The enzymatic activities of two SecA proteins from the same microorganism have not been defined for any bacteria. Here, M. tuberculosis SecA1 and SecA2 are shown to bind ATP with high affinity, though the affinity of SecA1 for ATP is weaker than that of SecA2 or Escherichia coli SecA. Amino acid substitution of arginine or alanine for the conserved lysine in the Walker A motif of SecA2 eliminated ATP binding. We used the SecA2(K115R) variant to show that ATP binding was necessary for the SecA2 function of promoting intracellular growth of M. tuberculosis in macrophages. These results are the first to show the importance of ATPase activity in the function of accessory SecA2 proteins.
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146
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Caspers M, Freudl R. Corynebacterium glutamicum possesses two secA homologous genes that are essential for viability. Arch Microbiol 2008; 189:605-10. [PMID: 18246326 DOI: 10.1007/s00203-008-0351-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Revised: 12/17/2007] [Accepted: 01/15/2008] [Indexed: 11/25/2022]
Abstract
SecA is a central component of the bacterial Sec preprotein translocase. Besides the housekeeping SecA (SecA1), some mostly pathogenic Gram-positive bacteria possess an accessory SecA (SecA2) that is involved in the export of a few substrates only. Here we show that neither of the two secA homologous genes present in the genome of the non-pathogenic bacterium Corynebacterium glutamicum can be deleted, unless a copy of the respective gene is provided in trans on a plasmid. This finding is in marked contrast to all other cases examined so far making C. glutamicum the first reported bacterium possessing two essential SecA proteins.
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Affiliation(s)
- Michael Caspers
- Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, Jülich, Germany
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147
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Briken V. Molecular mechanisms of host-pathogen interactions and their potential for the discovery of new drug targets. Curr Drug Targets 2008; 9:150-7. [PMID: 18288966 PMCID: PMC2650272 DOI: 10.2174/138945008783502449] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Vaccines and chemotherapy have undeniably been the discoveries in the field of biomedical research that have exerted the biggest impact on the improvement of public health. Nevertheless, the development of bacterial resistance to antibiotics has co-evolved over time with the discovery of new drugs. This entails the necessity for continuous research on new anti-infectious agents. The current review highlights recent discoveries in the molecular mechanisms of specific host pathogen interactions and their potential for drug discovery. The focus is on facultative and obligate intracellular pathogens (Mycobacterium, Chlamydia and Legionella) and their manipulation of host cells in regard to inhibition of phagosome maturation and cell death. Furthermore, the composition and role of the SecA2 and the ESX-1 secretion pathways in bacterial virulence and manipulation of infected host cells is discussed. The central hypothesis proposed in this review is that the characterization of bacterial proteins and lipids involved in host cell manipulation (modulins) will provide an abundance of new drug targets. One advantage of targeting such bacterial modulins for drug development is that these anti-modulin drugs will not disrupt the beneficial host microflora and therefore have fewer side effects.
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Affiliation(s)
- Volker Briken
- Department of Cell Biology and Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, Microbiology Bldg. 231, Room 2201, College Park, MD, 20742, USA.
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148
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McCann JR, McDonough JA, Pavelka MS, Braunstein M. Beta-lactamase can function as a reporter of bacterial protein export during Mycobacterium tuberculosis infection of host cells. MICROBIOLOGY-SGM 2007; 153:3350-3359. [PMID: 17906134 PMCID: PMC2635098 DOI: 10.1099/mic.0.2007/008516-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mycobacterium tuberculosis is an intracellular pathogen that is able to avoid destruction by host immune defences. Exported proteins of M. tuberculosis, which include proteins localized to the bacterial surface or secreted into the extracellular environment, are ideally situated to interact with host factors. As a result, these proteins are attractive candidates for virulence factors, drug targets and vaccine components. Here we describe a beta-lactamase reporter system capable of identifying exported proteins of M. tuberculosis during growth in host cells. Because beta-lactams target bacterial cell-wall synthesis, beta-lactamases must be exported beyond the cytoplasm to protect against these drugs. When used in protein fusions, beta-lactamase can report on the subcellular location of another protein as measured by protection from beta-lactam antibiotics. Here we demonstrate that a truncated TEM-1 beta-lactamase lacking a signal sequence for export ('BlaTEM-1) can be used in this manner directly in a mutant strain of M. tuberculosis lacking the major beta-lactamase, BlaC. The 'BlaTEM-1 reporter conferred beta-lactam resistance when fused to both Sec and Tat export signal sequences. We further demonstrate that beta-lactamase fusion proteins report on protein export while M. tuberculosis is growing in THP-1 macrophage-like cells. This genetic system should facilitate the study of proteins exclusively exported in the host environment by intracellular M. tuberculosis.
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Affiliation(s)
- Jessica R. McCann
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7290
| | - Justin A. McDonough
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7290
| | - Martin S. Pavelka
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Miriam Braunstein
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7290
- Corresponding author. Mailing address: Department of Microbiology and Immunology, CB#7290, 804 Mary Ellen Jones, University of North Carolina, Chapel Hill, NC 27599-7290. Phone: (919) 966-5051. Fax: (919) 962-8103. E-mail:
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149
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Mujahid S, Pechan T, Wang C. Improved solubilization of surface proteins fromListeria monocytogenes for 2-DE. Electrophoresis 2007; 28:3998-4007. [DOI: 10.1002/elps.200600858] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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150
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Shi L, Sohaskey CD, North RJ, Gennaro ML. Transcriptional characterization of the antioxidant response of Mycobacterium tuberculosis in vivo and during adaptation to hypoxia in vitro. Tuberculosis (Edinb) 2007; 88:1-6. [PMID: 17928268 DOI: 10.1016/j.tube.2007.08.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 08/01/2007] [Accepted: 08/27/2007] [Indexed: 12/26/2022]
Abstract
Transcriptional profiling of antioxidant genes of Mycobacterium tuberculosis was performed by real-time RT-PCR during mouse lung infection and during adaptation to gradual oxygen depletion in vitro. M. tuberculosis genes involved in major detoxification pathways of oxidative stress were not up-regulated during chronic mouse lung infection, which is established in response to expression of host adaptive immunity. This result suggests that a major function of bacterial antioxidant enzymes is to protect from oxidants generated during the early, acute phase of infection. In vivo transcription profiles of bacterial antioxidant enzymes differed from those seen under adaptation to low oxygen in vitro, indicating differences between growth arrest in vivo and that induced by hypoxia in vitro.
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Affiliation(s)
- Lanbo Shi
- Public Health Research Institute, 225 Warren Street Newark, NJ 07103, USA
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