1
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Ali L, Abdel Aziz MH. Crosstalk involving two-component systems in Staphylococcus aureus signaling networks. J Bacteriol 2024; 206:e0041823. [PMID: 38456702 PMCID: PMC11025333 DOI: 10.1128/jb.00418-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024] Open
Abstract
Staphylococcus aureus poses a serious global threat to human health due to its pathogenic nature, adaptation to environmental stress, high virulence, and the prevalence of antimicrobial resistance. The signaling network in S. aureus coordinates and integrates various internal and external inputs and stimuli to adapt and formulate a response to the environment. Two-component systems (TCSs) of S. aureus play a central role in this network where surface-expressed histidine kinases (HKs) receive and relay external signals to their cognate response regulators (RRs). Despite the purported high fidelity of signaling, crosstalk within TCSs, between HK and non-cognate RR, and between TCSs and other systems has been detected widely in bacteria. The examples of crosstalk in S. aureus are very limited, and there needs to be more understanding of its molecular recognition mechanisms, although some crosstalk can be inferred from similar bacterial systems that share structural similarities. Understanding the cellular processes mediated by this crosstalk and how it alters signaling, especially under stress conditions, may help decipher the emergence of antibiotic resistance. This review highlights examples of signaling crosstalk in bacteria in general and S. aureus in particular, as well as the effect of TCS mutations on signaling and crosstalk.
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Affiliation(s)
- Liaqat Ali
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - May H. Abdel Aziz
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
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2
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Ge W, Yang Q, Wang H, Pan C, Lv M, Liang L, Ya S, Luo X, Wang W, Ma H. Acid tolerance response of Salmonella during the squid storage and its amine production capacity analysis. Arch Microbiol 2024; 206:139. [PMID: 38436732 DOI: 10.1007/s00203-024-03853-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 03/05/2024]
Abstract
Salmonella exhibits a strong inducible acid tolerance response (ATR) under weak acid conditions, and can also induce high-risk strains that are highly toxic, acid resistant, and osmotic pressure resistant to aquatic products. However, the induction mechanism is not yet clear. Therefore, this study aims to simulate the slightly acidic, low-temperature, and high-protein environment during squid processing and storage. Through λRed gene knockout, exploring the effects of low-acid induction, long-term low-temperature storage, and two-component regulation on Salmonella ATR. In this study, we found the two-component system, PhoP/PhoQ and PmrA/PmrB in Salmonella regulates the amino acid metabolism system and improves bacterial acid tolerance by controlling arginine and lysine. Compared with the two indicators of total biogenic amine and diamine content, biogenic amine index and quality index were more suitable for evaluating the quality of aquatic products. The result showed that low-temperature treatment could inhibit Salmonella-induced ATR, which further explained the ATR mechanism from the amino acid metabolism.
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Affiliation(s)
- Wei Ge
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Qiong Yang
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Hui Wang
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Chuanyan Pan
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Min Lv
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Lingyun Liang
- Aquatic Technology Promotion Station in Jinchengjiang District, Hechi, 547000, China
| | - Shiya Ya
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Xu Luo
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Weisheng Wang
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, 530200, China.
| | - Huawei Ma
- Guangxi Engineering Research Center of Processing and Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China.
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3
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Belardinelli JM, Arora D, Avanzi C, Wheat WH, Bryant JM, Spencer JS, Blundell TL, Parkhill J, Floto RA, Jackson M. Clinically relevant mutations in the PhoR sensor kinase of host-adapted Mycobacterium abscessus isolates impact response to acidic pH and virulence. Microbiol Spectr 2023; 11:e0158823. [PMID: 37874174 PMCID: PMC10715180 DOI: 10.1128/spectrum.01588-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/14/2023] [Indexed: 10/25/2023] Open
Abstract
IMPORTANCE Difficult-to-treat pulmonary infections caused by nontuberculous mycobacteria of the Mycobacterium abscessus group have been steadily increasing in the USA and globally. Owing to the relatively recent recognition of M. abscessus as a human pathogen, basic and translational research to address critical gaps in diagnosis, treatment, and prevention of diseases caused by this microorganism has been lagging behind that of the better-known mycobacterial pathogen, Mycobacterium tuberculosis. To begin unraveling the molecular mechanisms of pathogenicity of M. abscessus, we here focus on the study of a two-component regulator known as PhoPR which we found to be under strong evolutionary pressure during human lung infection. We show that PhoPR is activated at acidic pH and serves to regulate a defined set of genes involved in host adaptation. Accordingly, clinical isolates from chronically infected human lungs tend to hyperactivate this regulator enabling M. abscessus to escape macrophage killing.
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Affiliation(s)
- Juan M Belardinelli
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Divya Arora
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
| | - Charlotte Avanzi
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - William H Wheat
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Josephine M Bryant
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
- University of Cambridge Centre for AI in Medicine , Cambridge, United Kingdom
| | - John S Spencer
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge , Cambridge, United Kingdom
| | - Julian Parkhill
- Wellcome Sanger Institute , Hinxton, United Kingdom
- Department of Veterinary Medicine, University of Cambridge , Cambridge, United Kingdom
| | - R Andres Floto
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
- University of Cambridge Centre for AI in Medicine , Cambridge, United Kingdom
- Cambridge Centre for Lung Infection, Papworth Hospital , Cambridge, United Kingdom
| | - Mary Jackson
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
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4
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Vashist A, Malhotra V, Sharma G, Tyagi JS, Clark-Curtiss JE. Interplay of PhoP and DevR response regulators defines expression of the dormancy regulon in virulent Mycobacterium tuberculosis. J Biol Chem 2018; 293:16413-16425. [PMID: 30181216 PMCID: PMC6200940 DOI: 10.1074/jbc.ra118.004331] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/15/2018] [Indexed: 11/06/2022] Open
Abstract
The DevR response regulator of Mycobacterium tuberculosis is an established regulator of the dormancy response in mycobacteria and can also be activated during aerobic growth conditions in avirulent strains, suggesting a complex regulatory system. Previously, we reported culture medium-specific aerobic induction of the DevR regulon genes in avirulent M. tuberculosis H37Ra that was absent in the virulent H37Rv strain. To understand the underlying basis of this differential response, we have investigated aerobic expression of the Rv3134c-devR-devS operon using M. tuberculosis H37Ra and H37Rv devR overexpression strains, designated as LIX48 and LIX50, respectively. Overexpression of DevR led to the up-regulation of a large number of DevR regulon genes in aerobic cultures of LIX48, but not in LIX50. To ascertain the involvement of PhoP response regulator, also known to co-regulate a subset of DevR regulon genes, we complemented the naturally occurring mutant phoPRa gene of LIX48 with the WT phoPRv gene. PhoPRv dampened the induced expression of the DevR regulon by >70-80%, implicating PhoP in the negative regulation of devR expression. Electrophoretic mobility shift assays confirmed phosphorylation-independent binding of PhoPRv to the Rv3134c promoter and further revealed that DevR and PhoPRv proteins exhibit differential DNA binding properties to the target DNA. Through co-incubations with DNA, ELISA, and protein complementation assays, we demonstrate that DevR forms a heterodimer with PhoPRv but not with the mutant PhoPRa protein. The study puts forward a new possible mechanism for coordinated expression of the dormancy regulon, having implications in growth adaptations critical for development of latency.
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Affiliation(s)
- Atul Vashist
- the Department of Biotechnology, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Vandana Malhotra
- the Center for Infectious Diseases and Vaccinology, Biodesign Institute, and
- From the Department of Biochemistry, Sri Venkateswara College, University of Delhi, New Delhi 110021, India
| | - Gunjan Sharma
- the Department of Biotechnology, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Jaya Sivaswami Tyagi
- the Department of Biotechnology, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Josephine E Clark-Curtiss
- the Center for Infectious Diseases and Vaccinology, Biodesign Institute, and
- the School of Life Sciences, Arizona State University, Tempe, Arizona 85287, and
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5
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Acetylation of Lysine 201 Inhibits the DNA-Binding Ability of PhoP to Regulate Salmonella Virulence. PLoS Pathog 2016; 12:e1005458. [PMID: 26943369 PMCID: PMC4778762 DOI: 10.1371/journal.ppat.1005458] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 01/25/2016] [Indexed: 12/21/2022] Open
Abstract
The two-component system PhoP-PhoQ is highly conserved in bacteria and regulates virulence in response to various signals for bacteria within the mammalian host. Here, we demonstrate that PhoP could be acetylated by Pat and deacetylated by deacetylase CobB enzymatically in vitro and in vivo in Salmonella Typhimurium. Specifically, the conserved lysine residue 201(K201) in winged helix-turn-helix motif at C-terminal DNA-binding domain of PhoP could be acetylated, and its acetylation level decreases dramatically when bacteria encounter low magnesium, acid stress or phagocytosis of macrophages. PhoP has a decreased acetylation and increased DNA-binding ability in the deletion mutant of pat. However, acetylation of K201 does not counteract PhoP phosphorylation, which is essential for PhoP activity. In addition, acetylation of K201 (mimicked by glutamine substitute) in S. Typhimurium causes significantly attenuated intestinal inflammation as well as systemic infection in mouse model, suggesting that deacetylation of PhoP K201 is essential for Salmonella pathogenesis. Therefore, we propose that the reversible acetylation of PhoP K201 may ensure Salmonella promptly respond to different stresses in host cells. These findings suggest that reversible lysine acetylation in the DNA-binding domain, as a novel regulatory mechanism of gene expression, is involved in bacterial virulence across microorganisms.
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6
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Macdonald R, Sarkar D, Amer BR, Clubb RT. Solution structure of the PhoP DNA-binding domain from Mycobacterium tuberculosis. JOURNAL OF BIOMOLECULAR NMR 2015; 63:111-117. [PMID: 26209027 PMCID: PMC4714862 DOI: 10.1007/s10858-015-9965-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/10/2015] [Indexed: 06/05/2023]
Abstract
Tuberculosis caused by Mycobacterium tuberculosis is a leading cause of death world-wide. The PhoP protein is required for virulence and is part of the PhoPR two-component system that regulates gene expression. The NMR-derived solution structure of the PhoP C-terminal DNA-binding domain is reported. Residues 150 to 246 form a structured domain that contains a winged helix-turn-helix motif. We provide evidence that the transactivation loop postulated to contact RNA polymerase is partially disordered in solution, and that the polypeptide that connects the DNA-binding domain to the regulatory domain is unstructured.
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Affiliation(s)
- Ramsay Macdonald
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 602 Boyer Hall, Los Angeles, CA, 90095, USA
- UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA, 90095, USA
| | - Dibyendu Sarkar
- CSIR-Institute of Microbial Technology, Sector-39A, Chandigarh, 160036, India
| | - Brendan R Amer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 602 Boyer Hall, Los Angeles, CA, 90095, USA
- UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA, 90095, USA
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 602 Boyer Hall, Los Angeles, CA, 90095, USA.
- Molecular Biology Institute, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA, 90095, USA.
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7
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He X, Wang S. DNA consensus sequence motif for binding response regulator PhoP, a virulence regulator of Mycobacterium tuberculosis. Biochemistry 2014; 53:8008-20. [PMID: 25434965 PMCID: PMC4283936 DOI: 10.1021/bi501019u] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Tuberculosis has reemerged as a serious
threat to human health
because of the increasing prevalence of drug-resistant strains and
synergetic infection with HIV, prompting an urgent need for new and
more efficient treatments. The PhoP–PhoR two-component system
of Mycobacterium tuberculosis plays an important
role in the virulence of the pathogen and thus represents a potential
drug target. To study the mechanism of gene transcription regulation
by response regulator PhoP, we identified a high-affinity DNA sequence
for PhoP binding using systematic evolution of ligands by exponential
enrichment. The sequence contains a direct repeat of two 7 bp motifs
separated by a 4 bp spacer, TCACAGC(N4)TCACAGC. The specificity
of the direct-repeat sequence for PhoP binding was confirmed by isothermal
titration calorimetry and electrophoretic mobility shift assays. PhoP
binds to the direct repeat as a dimer in a highly cooperative manner.
We found many genes previously identified to be regulated by PhoP
that contain the direct-repeat motif in their promoter sequences.
Synthetic DNA fragments at the putative promoter-binding sites bind
PhoP with variable affinity, which is related to the number of mismatches
in the 7 bp motifs, the positions of the mismatches, and the spacer
and flanking sequences. Phosphorylation of PhoP increases the affinity
but does not change the specificity of DNA binding. Overall, our results
confirm the direct-repeat sequence as the consensus motif for PhoP
binding and thus pave the way for identification of PhoP directly
regulated genes in different mycobacterial genomes.
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Affiliation(s)
- Xiaoyuan He
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences , Bethesda, Maryland 20814, United States
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8
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Das AK, Kumar VA, Sevalkar RR, Bansal R, Sarkar D. Unique N-terminal arm of Mycobacterium tuberculosis PhoP protein plays an unusual role in its regulatory function. J Biol Chem 2013; 288:29182-92. [PMID: 23963455 DOI: 10.1074/jbc.m113.499905] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Mycobacterium tuberculosis PhoP, a master regulator involved in complex lipid biosynthesis and expression of unknown virulence determinants, is composed of an N-terminal receiver domain and a C-terminal effector domain. The two experimentally characterized PhoP orthologs, from Escherichia coli and Salmonella enterica, display vastly different regulatory capabilities. Here, we demonstrate that the 20-residue-long N-terminal arm unique to M. tuberculosis PhoP plays an essential role in the expanded regulatory capabilities of this important regulator. Although the arm is not required for overall structural stability and/or phosphorylation of the PhoP N-domain, strikingly it is essential for phosphorylation-coupled transcription regulation of target genes. Consistent with this view, arm truncation of PhoP is accompanied by a conformational change of the effector domain, presenting a block in activation subsequent to phosphorylation. These results suggest that presence of the arm, unique to this regulator that shares an otherwise highly conserved domain structure with members of the protein family, contributes to the mechanism of inter-domain interactions. Thus, we propose that the N-terminal arm is an adaptable structural feature of M. tuberculosis PhoP, which evolved to fine-tune regulatory capabilities of the transcription factor in response to the changing physiology of the bacilli within its host.
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Affiliation(s)
- Arijit Kumar Das
- From the CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India
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9
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Structure-function studies of DNA binding domain of response regulator KdpE reveals equal affinity interactions at DNA half-sites. PLoS One 2012; 7:e30102. [PMID: 22291906 PMCID: PMC3264566 DOI: 10.1371/journal.pone.0030102] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 12/13/2011] [Indexed: 12/04/2022] Open
Abstract
Expression of KdpFABC, a K+ pump that restores osmotic balance, is controlled by binding of the response regulator KdpE to a specific DNA sequence (kdpFABCBS) via the winged helix-turn-helix type DNA binding domain (KdpEDBD). Exploration of E. coli KdpEDBD and kdpFABCBS interaction resulted in the identification of two conserved, AT-rich 6 bp direct repeats that form half-sites. Despite binding to these half-sites, KdpEDBD was incapable of promoting gene expression in vivo. Structure-function studies guided by our 2.5 Å X-ray structure of KdpEDBD revealed the importance of residues R193 and R200 in the α-8 DNA recognition helix and T215 in the wing region for DNA binding. Mutation of these residues renders KdpE incapable of inducing expression of the kdpFABC operon. Detailed biophysical analysis of interactions using analytical ultracentrifugation revealed a 2∶1 stoichiometry of protein to DNA with dissociation constants of 200±100 and 350±100 nM at half-sites. Inactivation of one half-site does not influence binding at the other, indicating that KdpEDBD binds independently to the half-sites with approximately equal affinity and no discernable cooperativity. To our knowledge, these data are the first to describe in quantitative terms the binding at half-sites under equilibrium conditions for a member of the ubiquitous OmpR/PhoB family of proteins.
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10
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Bretl DJ, Demetriadou C, Zahrt TC. Adaptation to environmental stimuli within the host: two-component signal transduction systems of Mycobacterium tuberculosis. Microbiol Mol Biol Rev 2011; 75:566-82. [PMID: 22126994 PMCID: PMC3232741 DOI: 10.1128/mmbr.05004-11] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pathogenic microorganisms encounter a variety of environmental stresses following infection of their respective hosts. Mycobacterium tuberculosis, the etiological agent of tuberculosis, is an unusual bacterial pathogen in that it is able to establish lifelong infections in individuals within granulomatous lesions that are formed following a productive immune response. Adaptation to this highly dynamic environment is thought to be mediated primarily through transcriptional reprogramming initiated in response to recognition of stimuli, including low-oxygen tension, nutrient depletion, reactive oxygen and nitrogen species, altered pH, toxic lipid moieties, cell wall/cell membrane-perturbing agents, and other environmental cues. To survive continued exposure to these potentially adverse factors, M. tuberculosis encodes a variety of regulatory factors, including 11 complete two-component signal transduction systems (TCSSs) and several orphaned response regulators (RRs) and sensor kinases (SKs). This report reviews our current knowledge of the TCSSs present in M. tuberculosis. In particular, we discuss the biochemical and functional characteristics of individual RRs and SKs, the environmental stimuli regulating their activation, the regulons controlled by the various TCSSs, and the known or postulated role(s) of individual TCSSs in the context of M. tuberculosis physiology and/or pathogenesis.
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Affiliation(s)
| | | | - Thomas C. Zahrt
- Center for Infectious Disease Research and Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226-0509
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11
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Menon S, Wang S. Structure of the response regulator PhoP from Mycobacterium tuberculosis reveals a dimer through the receiver domain. Biochemistry 2011; 50:5948-57. [PMID: 21634789 DOI: 10.1021/bi2005575] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The PhoP protein from Mycobacterium tuberculosis is a response regulator of the OmpR/PhoB subfamily, whose structure consists of an N-terminal receiver domain and a C-terminal DNA-binding domain. How the DNA-binding activities are regulated by phosphorylation of the receiver domain remains unclear due to a lack of structural information on the full-length proteins. Here we report the crystal structure of the full-length PhoP of M. tuberculosis. Unlike other known structures of full-length proteins of the same subfamily, PhoP forms a dimer through its receiver domain with the dimer interface involving α4-β5-α5, a common interface for activated receiver domain dimers. However, the switch residues, Thr99 and Tyr118, are in a conformation resembling those of nonactivated receiver domains. The Tyr118 side chain is involved in the dimer interface interactions. The receiver domain is tethered to the DNA-binding domain through a flexible linker and does not impose structural constraints on the DNA-binding domain. This structure suggests that phosphorylation likely facilitates/stabilizes receiver domain dimerization, bringing the DNA-binding domains to close proximity, thereby increasing their binding affinity for direct repeat DNA sequences.
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Affiliation(s)
- Smita Menon
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, United States
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12
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Pathak A, Goyal R, Sinha A, Sarkar D. Domain structure of virulence-associated response regulator PhoP of Mycobacterium tuberculosis: role of the linker region in regulator-promoter interaction(s). J Biol Chem 2010; 285:34309-18. [PMID: 20814030 DOI: 10.1074/jbc.m110.135822] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The PhoP and PhoR proteins from Mycobacterium tuberculosis form a highly specific two-component system that controls expression of genes involved in complex lipid biosynthesis and regulation of unknown virulence determinants. The several functions of PhoP are apportioned between a C-terminal effector domain (PhoPC) and an N-terminal receiver domain (PhoPN), phosphorylation of which regulates activation of the effector domain. Here we show that PhoPN, on its own, demonstrates PhoR-dependent phosphorylation. PhoPC, the truncated variant bearing the DNA binding domain, binds in vitro to the target site with affinity similar to that of the full-length protein. To complement the finding that residues spanning Met(1) to Arg(138) of PhoP constitute the minimal functional PhoPN, we identified Arg(150) as the first residue of the distal PhoPC domain capable of DNA binding on its own, thereby identifying an interdomain linker. However, coupling of two functional domains together in a single polypeptide chain is essential for phosphorylation-coupled DNA binding by PhoP. We discuss consequences of tethering of two domains on DNA binding and demonstrate that linker length and not individual residues of the newly identified linker plays a critical role in regulating interdomain interactions. Together, these results have implications for the molecular mechanism of transmission of conformation change associated with phosphorylation of PhoP that results in the altered DNA recognition by the C-terminal domain.
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Affiliation(s)
- Anuj Pathak
- Institute of Microbial Technology, Council of Scientific and Industrial Research, Sector 39A, Chandigarh 160036, India
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