1
|
Das M, David D, Horo I, Van Hooij A, Tió-Coma M, Geluk A, Vedithi SC. Mycobacterium leprae and host immune transcriptomic signatures for reactional states in leprosy. Front Microbiol 2023; 14:1113318. [PMID: 37051521 PMCID: PMC10083373 DOI: 10.3389/fmicb.2023.1113318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/03/2023] [Indexed: 03/29/2023] Open
Abstract
BackgroundMycobacterium leprae transcriptomic and human host immune gene expression signatures that demonstrate a plausible association with type I (T1R) and type II reactions (T2R) aid in early diagnosis, prevention of nerve damage and consequent demyelinating neuropathy in leprosy. The aim of the study is to identify M. leprae and host-associated gene-expression signatures that are associated with reactional states in leprosy.MethodsThe differentially expressed genes from the whole transcriptome of M. leprae were determined using genome-wide hybridization arrays with RNA extracted from skin biopsies of 20 T1R, 20 T2R and 20 non reactional controls (NR). Additionally, human immune gene-expressions were profiled using RT2-PCR profiler arrays and real-time qPCRs.ResultsThe RNA quality was optimal in 16 NR, 18 T1R and 19 T2R samples. Whole transcriptome expression array of these samples revealed significant upregulation of the genes that encode integral and intrinsic membrane proteins, hydrolases and oxidoreductases. In T1R lesional skin biopsy specimens, the top 10 significantly upregulated genes are ML2064, ML1271, ML1960, ML1220, ML2498, ML1996, ML2388, ML0429, ML2030 and ML0224 in comparison to NR. In T2R, genes ML2498, ML1526, ML0394, ML1960, ML2388, ML0429, ML0281, ML1847, ML1618 and ML1271 were significantly upregulated. We noted ML2664 was significantly upregulated in T1R and repressed in T2R. Conversely, we have not noted any genes upregulated in T2R and repressed in T1R. In both T1R and T2R, ML2388 was significantly upregulated. This gene encodes a probable membrane protein and epitope prediction using Bepipred-2.0 revealed a distinct B-cell epitope. Overexpression of ML2388 was noted consistently across the reaction samples. From the host immune gene expression profiles, genes for CXCL9, CXCL10, CXCL2, CD40LG, IL17A and CXCL11 were upregulated in T1R when compared to the NR. In T2R, CXCL10, CXCL11, CXCL9, CXCL2 and CD40LG were upregulated when compared to the NR group.ConclusionA gene set signature involving bacterial genes ML2388, ML2664, and host immune genes CXCL10 and IL-17A can be transcriptomic markers for reactional states in leprosy.
Collapse
Affiliation(s)
- Madhusmita Das
- Molecular Biology and Immunology Division, Schieffelin Institute of Health Research and Leprosy Centre, Karigiri, Vellore, Tamil Nadu, India
- *Correspondence: Madhusmita Das,
| | - Diana David
- Molecular Biology and Immunology Division, Schieffelin Institute of Health Research and Leprosy Centre, Karigiri, Vellore, Tamil Nadu, India
| | - Ilse Horo
- Molecular Biology and Immunology Division, Schieffelin Institute of Health Research and Leprosy Centre, Karigiri, Vellore, Tamil Nadu, India
| | - Anouk Van Hooij
- Department of Infectious Diseases, Leiden University Medical Centre, Leiden, Netherlands
| | - Maria Tió-Coma
- Department of Infectious Diseases, Leiden University Medical Centre, Leiden, Netherlands
| | - Annemieke Geluk
- Department of Infectious Diseases, Leiden University Medical Centre, Leiden, Netherlands
| | | |
Collapse
|
2
|
Rehna EA, Munavar H, Dharmalingam K, Shakila M, Natesan S. Mycobacterium leprae hsp18 promoter-EGFP transcriptional fusion construct: Environmental stress and strain-specific expression. Gene 2022; 851:147034. [DOI: 10.1016/j.gene.2022.147034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 10/25/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
|
3
|
Krismawati H, Oktavian A, Maladan Y, Wahyuni T. Risk factor for <em>Mycobacterium leprae</em> detection in household contacts with leprosy patients: a study in Papua, East Indonesia. MEDICAL JOURNAL OF INDONESIA 2020. [DOI: 10.13181/mji.oa.192962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
BACKGROUND In the era of leprosy eradication, Jayapura is still one of the biggest leprosy pockets in Papua, Indonesia. The trend for leprosy case detection rate has remained relatively stable over recent years. This study was aimed to detect Mycobacterium leprae in household contacts and to evaluate the associated factors with the detection. METHODS This cross-sectional study recruited household contacts of leprosy patients who were diagnosed consecutively from March to August 2015 in Hamadi Point of Care, Jayapura. The leprosy patients were diagnosed using polymerase chain reaction (PCR). For each leprosy patient, up to four household contacts that had no symptom were included. Every household contact received screening through DNA detection of M. leprae extracted from nasal swab specimens and examined using PCR. Factors for bacteria detection included intensity, time duration and number of contacts living together in the same house, and random blood glucose levels were evaluated. Bivariate analysis was used to associate them with M. leprae detection in household contacts. RESULTS From 107 household contacts of 35 patients who had leprosy, M. leprae was detected in 19.6%. Household contacts with leprosy patients for >1 year was a risk factor for detection (OR = 12.45; 95% CI = 1.595–97.20; p = 0.002). Blood glucose (p = 0.444), ethnic (p = 0.456), sleeping proximity to leprosy case (p = 0.468) and relatives (p = 0.518) give no effect to M. leprae detection in household contacts. CONCLUSIONS Among the various risk factors studied, duration of living together with the patient significantly increased the risk of M. leprae transmission.
Collapse
|
4
|
Treatment of Peripheral Neuropathy in Leprosy: The Case for Nerve Decompression. PLASTIC AND RECONSTRUCTIVE SURGERY-GLOBAL OPEN 2016; 4:e637. [PMID: 27257567 PMCID: PMC4874281 DOI: 10.1097/gox.0000000000000641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 02/01/2016] [Indexed: 11/26/2022]
Abstract
Supplemental Digital Content is available in the text. Plastic surgery has a tradition of caring for patients with facial deformity and hand deformity related to leprosy. The approach, however, to the progressive deformity and disability related to chronic nerve compression is underappreciated in the world today. A cohort of patients with leprous neuropathy from an indigenous area of leprosy in Ecuador was evaluated for the presence of chronic peripheral nerve compression, and 12 patients were chosen for simultaneous upper and lower extremity, unilateral, nerve decompression at multiple levels along the course of each nerve. The results at 1 year of follow-up show that 6 patients improved into the excellent category and 4 patients improved into the good category for improved function. Based on the early results in this small cohort of patients with leprous neuropathy, an approach to peripheral nerve decompression, encompassing the concept of multiple crush at multiple levels of each nerve, seems to offer optimism to improve upper and lower extremity limb function. Long-term studies with quality-of-life outcomes would be welcome.
Collapse
|
5
|
Sigma Factors: Key Molecules in Mycobacterium tuberculosis Physiology and Virulence. Microbiol Spectr 2015; 2:MGM2-0007-2013. [PMID: 26082107 DOI: 10.1128/microbiolspec.mgm2-0007-2013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rapid adaptation to changing environments is one of the keys to the success of microorganisms. Since infection is a dynamic process, it is possible to predict that Mycobacterium tuberculosis adaptation involves continuous modulation of its global transcriptional profile in response to the changing environment found in the human body. In the last 18 years several studies have stressed the role of sigma (σ) factors in this process. These are small interchangeable subunits of the RNA polymerase holoenzyme that are required for transcriptional initiation and that determine promoter specificity. The M. tuberculosis genome encodes 13 of these proteins, one of which--the principal σ factor σA--is essential. Of the other 12 σ factors, at least 6 are required for virulence. In this article we review our current knowledge of mycobacterial σ factors, their regulons, the complex mechanisms determining their regulation, and their roles in M. tuberculosis physiology and virulence.
Collapse
|
6
|
Parijat P, Batra JK. Role of DnaK in HspR-HAIR interaction of Mycobacterium tuberculosis. IUBMB Life 2015; 67:816-27. [PMID: 26442450 DOI: 10.1002/iub.1438] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 09/17/2015] [Indexed: 01/17/2023]
Abstract
Heat shock proteins (Hsps) are a highly conserved family of proteins. The regulation of expression of Hsps in Mycobacterium tuberculosis, is regulated both positively and negatively by alternate sigma factors and transcriptional DNA repressors, respectively. HspR is a negative regulator of expression of hsps, DnaK, ClpB, and Acr2 in M. tuberculosis. In this study, we expressed the M. tuberculosis HspR (MtHspR) in E. coli, and functionally characterized it. MtHspR independently bound to its putative cognate DNA, the HAIR element. MtHspR was found to exist in a dynamic mixture of dimeric and monomeric protein and presence of salt led to the formation of trimers which lacked the DNA binding activity. MtHspR was found to be heat stable with a Tm of 66°C. HspR-HAIR binding was stable upto 60°C suggesting that MtHspR is not the heat stress sensor. Mycobacterial DnaK was found to interact directly with MtHspR-HAIR complex in vitro in an ATP independent manner. The DnaK-HspR-HAIR binding pattern altered at high temperatures in the presence of aggregated α-casein substrate, suggesting that DnaK may indirectly be responding to heat stress in a feedback loop mechanism.
Collapse
Affiliation(s)
- Priyanka Parijat
- Immunochemistry Laboratory, National Institute of Immunology, New Delhi, India
| | - Janendra K Batra
- Immunochemistry Laboratory, National Institute of Immunology, New Delhi, India.,Centre for Molecular Medicine, National Institute of Immunology, New Delhi, India
| |
Collapse
|
7
|
The MprB extracytoplasmic domain negatively regulates activation of the Mycobacterium tuberculosis MprAB two-component system. J Bacteriol 2013; 196:391-406. [PMID: 24187094 DOI: 10.1128/jb.01064-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mycobacterium tuberculosis is an acid-fast pathogen of humans and the etiological agent of tuberculosis (TB). It is estimated that one-third of the world's population is latently (persistently) infected with M. tuberculosis. M. tuberculosis persistence is regulated, in part, by the MprAB two-component signal transduction system, which is activated by and mediates resistance to cell envelope stress. Here we identify MprAB as part of an evolutionarily conserved cell envelope stress response network and demonstrate that MprAB-mediated signal transduction is negatively regulated by the MprB extracytoplasmic domain (ECD). In particular, we report that deregulated production of the MprB sensor kinase, or of derivatives of this protein, negatively impacts M. tuberculosis growth. The observed growth attenuation is dependent on MprAB-mediated signal transduction and is exacerbated in strains of M. tuberculosis producing an MprB variant lacking its ECD. Interestingly, full-length MprB, and the ECD of MprB specifically, immunoprecipitates the Hsp70 chaperone DnaK in vivo, while overexpression of dnaK inhibits MprAB-mediated signal transduction in M. tuberculosis grown in the absence or presence of cell envelope stress. We propose that under nonstress conditions, or under conditions in which proteins present in the extracytoplasmic space are properly folded, signaling through the MprAB system is inhibited by the MprB ECD. Following exposure to cell envelope stress, proteins present in the extracytoplasmic space become unfolded or misfolded, leading to removal of the ECD-mediated negative regulation of MprB and subsequent activation of MprAB.
Collapse
|
8
|
Worobec SM. Current approaches and future directions in the treatment of leprosy. Res Rep Trop Med 2012; 3:79-91. [PMID: 30100775 DOI: 10.2147/rrtm.s27395] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This review surveys current treatments and future treatment trends in leprosy from a clinical perspective. The World Health Organization provides a multidrug treatment regimen that targets the Mycobacterium leprae bacillus which causes leprosy. Several investigational drugs are available for the treatment of drug-resistant M. leprae. Future directions in leprosy treatment will focus on: the molecular signaling mechanism M. leprae uses to avoid triggering an immune response; prospective studies of the side effects experienced during multiple-drug therapy; recognition of relapse rates post-completion of designated treatments; combating multidrug resistance; vaccine development; development of new diagnostic tests; and the implications of the recent discovery of a genetically distinct leprosy-causing bacillus, Mycobacterium lepromatosis.
Collapse
Affiliation(s)
- Sophie M Worobec
- Department of Dermatology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA,
| |
Collapse
|
9
|
Wiker HG, Tomazella GG, de Souza GA. A quantitative view on Mycobacterium leprae antigens by proteomics. J Proteomics 2011; 74:1711-9. [PMID: 21278007 DOI: 10.1016/j.jprot.2011.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 12/09/2010] [Accepted: 01/10/2011] [Indexed: 11/29/2022]
Abstract
Leprosy is an ancient disease and the focus of the researchers' scrutiny for more than a century. However, many of the molecular aspects related to transmission, virulence, antigens and immune responses are far from known. Initially, the implementation of recombinant DNA library screens raised interesting antigen candidates. Finally, the availability of Mycobacterium leprae genomic information showed an intriguing genome reduction which is now largely used in comparative genomics. While predictive in silico tools are commonly used to identify possible antigens, proteomic approaches have not yet been explored fully to study M. leprae biology. Quantitative information obtained at the protein level, and its analysis as part of a complex system, would be a key feature to be used to help researchers to validate and understand many of such in silico predictions. Through a re-analysis of data from a previous publication of our group, we could easily tackle many questions regarding antigen prediction and pseudogene expression. Several well known antigens are among the quantitatively dominant proteins, while several major proteins have not been explored as antigens. We argue that combining proteomic approaches together with bioinformatic workflows is a required step in the characterization of important pathogens.
Collapse
Affiliation(s)
- Harald G Wiker
- The Gade Institute, Section for Microbiology and Immunology, University of Bergen, Norway.
| | | | | |
Collapse
|
10
|
Akama T, Tanigawa K, Kawashima A, Wu H, Ishii N, Suzuki K. Analysis of Mycobacterium leprae gene expression using DNA microarray. Microb Pathog 2010; 49:181-5. [PMID: 20553838 DOI: 10.1016/j.micpath.2010.05.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 05/19/2010] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
Abstract
Mycobacterium leprae, the causative agent of leprosy, does not grow under in vitro condition, making molecular analysis of this bacterium difficult. For this reason, bacteriological information regarding M. leprae gene function is limited compared with other mycobacterium species. In this study, we performed DNA microarray analysis to clarify the RNA expression profile of the Thai53 strain of M. leprae grown in footpads of hypertensive nude rats (SHR/NCrj-rnu). Of 1605 M. leprae genes, 315 showed signal intensity twofold higher than the median. These genes include Acyl-CoA metabolic enzymes and drug metabolic enzymes, which might be related to the virulence of M. leprae. In addition, consecutive RNA expression profile and in silico analyses enabled identification of possible operons within the M. leprae genome. The present results will shed light on M. leprae gene function and further our understanding of the pathogenesis of leprosy.
Collapse
Affiliation(s)
- Takeshi Akama
- Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
11
|
Sachdeva P, Misra R, Tyagi AK, Singh Y. The sigma factors of Mycobacterium tuberculosis: regulation of the regulators. FEBS J 2009; 277:605-26. [DOI: 10.1111/j.1742-4658.2009.07479.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
12
|
Cook GM, Berney M, Gebhard S, Heinemann M, Cox RA, Danilchanka O, Niederweis M. Physiology of mycobacteria. Adv Microb Physiol 2009; 55:81-182, 318-9. [PMID: 19573696 DOI: 10.1016/s0065-2911(09)05502-7] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mycobacterium tuberculosis is a prototrophic, metabolically flexible bacterium that has achieved a spread in the human population that is unmatched by any other bacterial pathogen. The success of M. tuberculosis as a pathogen can be attributed to its extraordinary stealth and capacity to adapt to environmental changes throughout the course of infection. These changes include: nutrient deprivation, hypoxia, various exogenous stress conditions and, in the case of the pathogenic species, the intraphagosomal environment. Knowledge of the physiology of M. tuberculosis during this process has been limited by the slow growth of the bacterium in the laboratory and other technical problems such as cell aggregation. Advances in genomics and molecular methods to analyze the M. tuberculosis genome have revealed that adaptive changes are mediated by complex regulatory networks and signals, resulting in temporal gene expression coupled to metabolic and energetic changes. An important goal for bacterial physiologists will be to elucidate the physiology of M. tuberculosis during the transition between the diverse conditions encountered by M. tuberculosis. This review covers the growth of the mycobacterial cell and how environmental stimuli are sensed by this bacterium. Adaptation to different environments is described from the viewpoint of nutrient acquisition, energy generation, and regulation. To gain quantitative understanding of mycobacterial physiology will require a systems biology approach and recent efforts in this area are discussed.
Collapse
Affiliation(s)
- Gregory M Cook
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | | | | | | | | | | | | |
Collapse
|
13
|
Williams DL, Slayden RA, Amin A, Martinez AN, Pittman TL, Mira A, Mitra A, Nagaraja V, Morrison NE, Moraes M, Gillis TP. Implications of high level pseudogene transcription in Mycobacterium leprae. BMC Genomics 2009; 10:397. [PMID: 19706172 PMCID: PMC2753549 DOI: 10.1186/1471-2164-10-397] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Accepted: 08/25/2009] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The Mycobacterium leprae genome has less than 50% coding capacity and 1,133 pseudogenes. Preliminary evidence suggests that some pseudogenes are expressed. Therefore, defining pseudogene transcriptional and translational potentials of this genome should increase our understanding of their impact on M. leprae physiology. RESULTS Gene expression analysis identified transcripts from 49% of all M. leprae genes including 57% of all ORFs and 43% of all pseudogenes in the genome. Transcribed pseudogenes were randomly distributed throughout the chromosome. Factors resulting in pseudogene transcription included: 1) co-orientation of transcribed pseudogenes with transcribed ORFs within or exclusive of operon-like structures; 2) the paucity of intrinsic stem-loop transcriptional terminators between transcribed ORFs and downstream pseudogenes; and 3) predicted pseudogene promoters. Mechanisms for translational "silencing" of pseudogene transcripts included the lack of both translational start codons and strong Shine-Dalgarno (SD) sequences. Transcribed pseudogenes also contained multiple "in-frame" stop codons and high Ka/Ks ratios, compared to that of homologs in M. tuberculosis and ORFs in M. leprae. A pseudogene transcript containing an active promoter, strong SD site, a start codon, but containing two in frame stop codons yielded a protein product when expressed in E. coli. CONCLUSION Approximately half of M. leprae's transcriptome consists of inactive gene products consuming energy and resources without potential benefit to M. leprae. Presently it is unclear what additional detrimental affect(s) this large number of inactive mRNAs has on the functional capability of this organism. Translation of these pseudogenes may play an important role in overall energy consumption and resultant pathophysiological characteristics of M. leprae. However, this study also demonstrated that multiple translational "silencing" mechanisms are present, reducing additional energy and resource expenditure required for protein production from the vast majority of these transcripts.
Collapse
Affiliation(s)
- Diana L Williams
- HRSA, BPHC, Division of National Hansen's Disease Programs, Laboratory Research Branch, Molecular Biology Research Department @ School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Richard A Slayden
- Rocky Mountain Regional Center of Excellence, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA
| | - Amol Amin
- Rocky Mountain Regional Center of Excellence, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA
| | - Alejandra N Martinez
- HRSA, BPHC, Division of National Hansen's Disease Programs, Laboratory Research Branch, Molecular Biology Research Department @ School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
- Leprosy Laboratory, Department, Tropical Medicine Institute Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, RJ, Brazil
| | - Tana L Pittman
- HRSA, BPHC, Division of National Hansen's Disease Programs, Laboratory Research Branch, Molecular Biology Research Department @ School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Alex Mira
- Center for Advanced Research in Public Health, CSISP, Area de Genomica y Salud, Valencia, Spain
| | - Anirban Mitra
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Norman E Morrison
- Center for Tuberculosis Research, Department of Medicine, Division of Infectious Diseases, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Milton Moraes
- Leprosy Laboratory, Department, Tropical Medicine Institute Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, RJ, Brazil
| | - Thomas P Gillis
- HRSA, BPHC, Division of National Hansen's Disease Programs, Laboratory Research Branch, Molecular Biology Research Department @ School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| |
Collapse
|
14
|
Abstract
A significant proportion of bacteria express two or more chaperonin genes. Chaperonins are a group of molecular chaperones, defined by sequence similarity, required for the folding of some cellular proteins. Chaperonin monomers have a mass of c. 60 kDa, and are typically found as large protein complexes containing 14 subunits arranged in two rings. The mechanism of action of the Escherichia coli GroEL protein has been studied in great detail. It acts by binding to unfolded proteins and enabling them to fold in a protected environment where they do not interact with any other proteins. GroEL can assist the folding of many proteins of different sizes, sequences, and structures, and homologues from many different bacteria can functionally replace GroEL in E. coli. What then are the functions of multiple chaperonins? Do they provide a mechanism for cells to increase their general chaperoning ability, or have they become specialized to take on specific novel cellular roles? Here I will review the genetic, biochemical, and phylogenetic evidence that has a bearing on this question, and show that there is good evidence for at least some specificity of function in multiple chaperonin genes.
Collapse
Affiliation(s)
- Peter A Lund
- School of Biosciences, University of Birmingham, Birmingham, UK.
| |
Collapse
|
15
|
Evidence of complex transcriptional, translational, and posttranslational regulation of the extracytoplasmic function sigma factor sigmaE in Mycobacterium tuberculosis. J Bacteriol 2008; 190:5963-71. [PMID: 18606740 DOI: 10.1128/jb.00622-08] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The extracytoplasmic factor (ECF) sigma factor sigma(E) is one of the most studied sigma factors of Mycobacterium tuberculosis. It has been shown to be involved in virulence as well as in survival under conditions of high temperature, alkaline pH, and exposure to detergents and oxidative stress. Unlike many ECF sigma factors, sigma(E) does not directly regulate the transcription of its own gene. Two promoters have been identified upstream of the sigE gene; one is regulated by the two-component system MprAB, while the other has been shown to be sigma(H) dependent. In this paper, we further characterize the regulation of sigma(E) by identifying its anti-sigma factor and a previously unknown promoter. Finally, we show that sigE can be translated from three different translational start codons, depending on the promoter used. Taken together, our data demonstrate that sigma(E) not only is subjected to complex transcriptional regulation but is also controlled at the translational and posttranslational levels.
Collapse
|
16
|
Critical role of a single position in the -35 element for promoter recognition by Mycobacterium tuberculosis SigE and SigH. J Bacteriol 2008; 190:2227-30. [PMID: 18192397 DOI: 10.1128/jb.01642-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterial SigE and SigH both initiate transcription from the sigB promoter, suggesting that they recognize similar sequences. Through mutational and primer extension analyses, we determined that SigE and SigH recognize nearly identical promoters, with differences at the 3' end of the -35 element distinguishing between SigE- and SigH-dependent promoters.
Collapse
|