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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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Chen X, Alakavuklar MA, Fiebig A, Crosson S. Cross-regulation in a three-component cell envelope stress signaling system of Brucella. mBio 2023; 14:e0238723. [PMID: 38032291 PMCID: PMC10746171 DOI: 10.1128/mbio.02387-23] [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: 09/06/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
IMPORTANCE As intracellular pathogens, Brucella must contend with a variety of host-derived stressors when infecting a host cell. The inner membrane, cell wall, and outer membrane, i.e. the cell envelope, of Brucella provide a critical barrier to host assault. A conserved regulatory mechanism known as two-component signaling (TCS) commonly controls transcription of genes that determine the structure and biochemical composition of the cell envelope during stress. We report the identification of previously uncharacterized TCS genes that determine Brucella ovis fitness in the presence of cell envelope disruptors and within infected mammalian host cells. Our study reveals a new molecular mechanism of TCS-dependent gene regulation, and thereby advances fundamental understanding of transcriptional regulatory processes in bacteria.
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Affiliation(s)
- Xingru Chen
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Melene A. Alakavuklar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Aretha Fiebig
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Sean Crosson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
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Zhang C, Liu M, Wu Y, Li X, Zhang C, Call DR, Liu M, Zhao Z. ArcB orchestrates the quorum-sensing system to regulate type III secretion system 1 in Vibrio parahaemolyticus. Gut Microbes 2023; 15:2281016. [PMID: 37982663 PMCID: PMC10841015 DOI: 10.1080/19490976.2023.2281016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/05/2023] [Indexed: 11/21/2023] Open
Abstract
In many Vibrio species, virulence is regulated by quorum sensing, which is regulated by a complex, multichannel, two-component phosphorelay circuit. Through this circuit, sensor kinases transmit sensory information to the phosphotransferase LuxU via a phosphotransfer mechanism, which in turn transmits the signal to the response regulator LuxO. For Vibrio parahaemolyticus, type III secretion system 1 (T3SS1) is required for cytotoxicity, but it is unclear how quorum sensing regulates T3SS1 expression. Herein, we report that a hybrid histidine kinase, ArcB, instead of LuxU, and sensor kinase LuxQ and response regulator LuxO, collectively orchestrate T3SS1 expression in V. parahaemolyticus. Under high oxygen conditions, LuxQ can interact with ArcB directly and phosphorylates the Hpt domain of ArcB. The Hpt domain of ArcB phosphorylates the downstream response regulator LuxO instead of ArcA. LuxO then activates transcription of the T3SS1 gene cluster. Under hypoxic conditions, ArcB autophosphorylates and phosphorylates ArcA, whereas ArcA does not participate in regulating the expression of T3SS1. Our data provides evidence of an alternative regulatory path involving the quorum sensing phosphorelay and adds another layer of understanding about the environmental regulation of gene expression in V. parahaemolyticus.
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Affiliation(s)
- Ce Zhang
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Min Liu
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Ying Wu
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Xixi Li
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Chen Zhang
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Douglas R. Call
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA, USA
| | - Ming Liu
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, National Clinical Research Center for Infectious Diseases, Shenzhen, Guangdong Province, China
| | - Zhe Zhao
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
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Patil RS, Sharma S, Bhaskarwar AV, Nambiar S, Bhat NA, Koppolu MK, Bhukya H. TetR and OmpR family regulators in natural product biosynthesis and resistance. Proteins 2023. [PMID: 37874037 DOI: 10.1002/prot.26621] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 08/30/2023] [Accepted: 10/06/2023] [Indexed: 10/25/2023]
Abstract
This article provides a comprehensive review and sequence-structure analysis of transcription regulator (TR) families, TetR and OmpR/PhoB, involved in specialized secondary metabolite (SSM) biosynthesis and resistance. Transcription regulation is a fundamental process, playing a crucial role in orchestrating gene expression to confer a survival advantage in response to frequent environmental stress conditions. This process, coupled with signal sensing, enables bacteria to respond to a diverse range of intra and extracellular signals. Thus, major bacterial signaling systems use a receptor domain to sense chemical stimuli along with an output domain responsible for transcription regulation through DNA-binding. Sensory and output domains on a single polypeptide chain (one component system, OCS) allow response to stimuli by allostery, that is, DNA-binding affinity modulation upon signal presence/absence. On the other hand, two component systems (TCSs) allow cross-talk between the sensory and output domains as they are disjoint and transmit information by phosphorelay to mount a response. In both cases, however, TRs play a central role. Biosynthesis of SSMs, which includes antibiotics, is heavily regulated by TRs as it diverts the cell's resources towards the production of these expendable compounds, which also have clinical applications. These TRs have evolved to relay information across specific signals and target genes, thus providing a rich source of unique mechanisms to explore towards addressing the rapid escalation in antimicrobial resistance (AMR). Here, we focus on the TetR and OmpR family TRs, which belong to OCS and TCS, respectively. These TR families are well-known examples of regulators in secondary metabolism and are ubiquitous across different bacteria, as they also participate in a myriad of cellular processes apart from SSM biosynthesis and resistance. As a result, these families exhibit higher sequence divergence, which is also evident from our bioinformatic analysis of 158 389 and 77 437 sequences from TetR and OmpR family TRs, respectively. The analysis of both sequence and structure allowed us to identify novel motifs in addition to the known motifs responsible for TR function and its structural integrity. Understanding the diverse mechanisms employed by these TRs is essential for unraveling the biosynthesis of SSMs. This can also help exploit their regulatory role in biosynthesis for significant pharmaceutical, agricultural, and industrial applications.
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Affiliation(s)
- Rachit S Patil
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Siddhant Sharma
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Aditya V Bhaskarwar
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Souparnika Nambiar
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Niharika A Bhat
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Mani Kanta Koppolu
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Hussain Bhukya
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
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5
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Chen X, Alakavuklar MA, Fiebig A, Crosson S. Cross regulation in a three-component cell envelope stress signaling system of Brucella. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.15.536747. [PMID: 37873345 PMCID: PMC10592609 DOI: 10.1101/2023.04.15.536747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
A multi-layered structure known as the cell envelope separates the controlled interior of bacterial cells from a fluctuating physical and chemical environment. The transcription of genes that determine cell envelope structure and function is commonly regulated by two-component signaling systems (TCS), comprising a sensor histidine kinase and a cognate response regulator. To identify TCS genes that contribute to cell envelope function in the intracellular mammalian pathogen, Brucella ovis, we subjected a collection of non-essential TCS deletion mutants to compounds that disrupt cell membranes and the peptidoglycan cell wall. Our screen led to the discovery of three TCS proteins that coordinately function to confer resistance to cell envelope stressors and to support B. ovis replication in the intracellular niche. This tripartite regulatory system includes the known cell envelope regulator, CenR, and a previously uncharacterized TCS, EssR-EssS, which is widely conserved in Alphaproteobacteria. The CenR and EssR response regulators bind a shared set of sites on the B. ovis chromosomes to control transcription of an overlapping set of genes with cell envelope functions. CenR directly interacts with EssR and functions to stimulate phosphoryl transfer from the EssS kinase to EssR, while CenR and EssR control the cellular levels of each other via a post-transcriptional mechanism. Our data provide evidence for a new mode of TCS cross-regulation in which a non-cognate response regulator affects both the activity and protein levels of a cognate TCS protein pair.
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Affiliation(s)
- Xingru Chen
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
| | - Melene A Alakavuklar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
| | - Aretha Fiebig
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
| | - Sean Crosson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
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6
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Brown AN, Anderson MT, Bachman MA, Mobley HLT. The ArcAB Two-Component System: Function in Metabolism, Redox Control, and Infection. Microbiol Mol Biol Rev 2022; 86:e0011021. [PMID: 35442087 PMCID: PMC9199408 DOI: 10.1128/mmbr.00110-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
ArcAB, also known as the Arc system, is a member of the two-component system family of bacterial transcriptional regulators and is composed of sensor kinase ArcB and response regulator ArcA. In this review, we describe the structure and function of these proteins and assess the state of the literature regarding ArcAB as a sensor of oxygen consumption. The bacterial quinone pool is the primary modulator of ArcAB activity, but questions remain for how this regulation occurs. This review highlights the role of quinones and their oxidation state in activating and deactivating ArcB and compares competing models of the regulatory mechanism. The cellular processes linked to ArcAB regulation of central metabolic pathways and potential interactions of the Arc system with other regulatory systems are also reviewed. Recent evidence for the function of ArcAB under aerobic conditions is challenging the long-standing characterization of this system as strictly an anaerobic global regulator, and the support for additional ArcAB functionality in this context is explored. Lastly, ArcAB-controlled cellular processes with relevance to infection are assessed.
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Affiliation(s)
- Aric N. Brown
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Mark T. Anderson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Michael A. Bachman
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Harry L. T. Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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7
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Matanza XM, López-Suárez L, do Vale A, Osorio CR. The two-component system RstAB regulates production of a polysaccharide capsule with a role in virulence in the marine pathogen Photobacterium damselae subsp. damselae. Environ Microbiol 2021; 23:4859-4880. [PMID: 34423883 DOI: 10.1111/1462-2920.15731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 06/23/2021] [Accepted: 07/21/2021] [Indexed: 12/29/2022]
Abstract
The marine bacterium Photobacterium damselae subsp. damselae (Pdd) causes disease in marine animals and humans. Previous studies demonstrated that mutation of the two-component system RstAB strongly impacts virulence of this pathogen, but the RstAB regulon has not been thoroughly elucidated. We here compared the transcriptomes of Pdd RM-71 and ΔrstA and ΔrstB derivatives using RNA-seq. In accordance with previous studies, RstAB positively regulated cytotoxins Dly, PhlyP and PhlyC. This analysis also demonstrated a positive regulation of outer membrane proteins, resistance against antimicrobials and potential virulence factors by this system. Remarkably, RstAB positively regulated two hitherto uncharacterised gene clusters involved in the synthesis of a polysaccharide capsule. Presence of a capsular layer in wild-type cells was confirmed by transmission electron microscopy, whereas rstA and rstB mutants were non-capsulated. Mutants for capsule synthesis genes, wza and wzc exhibited acapsular phenotypes, were impaired in resistance against the bactericidal action of fish serum and mucus, and were strongly impaired in virulence for fish, indicating a major role of capsule in virulence. Collectively, this study demonstrates that RstAB is a major positive regulator of key virulence factors including a polysaccharide capsule essential for full virulence in a pathogenic Photobacterium.
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Affiliation(s)
- Xosé M Matanza
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Laura López-Suárez
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Ana do Vale
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Carlos R Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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8
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Diversification of OmpA and OmpF of Yersinia ruckeri is independent of the underlying species phylogeny and evidence of virulence-related selection. Sci Rep 2021; 11:3493. [PMID: 33568758 PMCID: PMC7876001 DOI: 10.1038/s41598-021-82925-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/27/2021] [Indexed: 01/30/2023] Open
Abstract
Yersinia ruckeri is the causative agent of enteric redmouth disease (ERM) which causes economically significant losses in farmed salmonids, especially Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss, Walbaum). However, very little is known about the genetic relationships of disease-causing isolates in these two host species or about factors responsible for disease. Phylogenetic analyses of 16 representative isolates based on the nucleotide sequences of 19 housekeeping genes suggests that pathogenic Atlantic salmon and rainbow trout isolates represent distinct host-specific lineages. However, the apparent phylogenies of certain isolates has been influenced by horizontal gene transfer and recombinational exchange. Splits decomposition analysis demonstrated a net-like phylogeny based on the housekeeping genes, characteristic of recombination. Comparative analysis of the distribution of individual housekeeping gene alleles across the isolates demonstrated evidence of genomic mosaicism and recombinational exchange involving certain Atlantic salmon and rainbow trout isolates. Comparative nucleotide sequence analysis of the key outer membrane protein genes ompA and ompF revealed that the corresponding gene trees were both non-congruent with respect to the housekeeping gene phylogenies providing evidence that horizontal gene transfer has influenced the evolution of both these surface protein-encoding genes. Analysis of inferred amino acid sequence variation in OmpA identified a single variant, OmpA.1, that was present in serotype O1 and O8 isolates representing typical pathogenic strains in rainbow trout and Atlantic salmon, respectively. In particular, the sequence of surface-exposed loop 3 differed by seven amino acids to that of other Y. ruckeri isolates. These findings suggest that positive selection has likely influenced the presence of OmpA.1 in these isolates and that loop 3 may play an important role in virulence. Amino acid sequence variation of OmpF was greater than that of OmpA and was similarly restricted mainly to the surface-exposed loops. Two OmpF variants, OmpF.1 and OmpF.2, were associated with pathogenic rainbow trout and Atlantic salmon isolates, respectively. These OmpF proteins had very similar amino acid sequences suggesting that positive evolutionary pressure has also favoured the selection of these variants in pathogenic strains infecting both species.
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Cabezas CE, Laulié AM, Briones AC, Pardo-Esté C, Lorca DE, Cofré AA, Morales EH, Mora AY, Krüger GI, Bueno SM, Hidalgo AA, Saavedra CP. Activation of regulator ArcA in the presence of hypochlorite in Salmonella enterica serovar Typhimurium. Biochimie 2020; 180:178-185. [PMID: 33188860 DOI: 10.1016/j.biochi.2020.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 11/04/2020] [Accepted: 11/05/2020] [Indexed: 01/24/2023]
Abstract
Oxidative stress is the main mechanism behind efficient disinfectants, causing damage in bacterial macromolecules. Importantly, bacteria activate resistance mechanisms in response to damage generated by oxidative stress. Strategies allowing pathogens to survive oxidative stress are highly conserved among microorganisms. Many of these strategies entail genomic responses triggered by signals transduced through Two Component Systems (TCS). Recently, we demonstrated that the TCS ArcAB (specifically ArcA) participates in bacterial responses to hypochlorite, regulating the uptake of this toxic compound and being involved in resistance and survival inside neutrophils, where hypochlorous acid abounds. Here, we demonstrated that ArcA is required in the response to oxidative stress generated by hypochlorite, independent of its cognate sensor ArcB or the Asp54 of ArcA, the only phosphorylable residue in ArcA, which is required to function as a gene regulator. Our results suggest that ArcA could have additional functions to respond to oxidative stress, independent of its regulatory activity, which might require interaction with other unknown relevant proteins.
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Affiliation(s)
- Carolina E Cabezas
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Arlette M Laulié
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alan C Briones
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Diego E Lorca
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Agustin A Cofré
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | | | - Aracely Y Mora
- Laboratorio de patogénesis molecular y antimicrobianos y Escuela de Química y Farmacia, Universidad Andres Bello, Santiago, Chile
| | - Gabriel I Krüger
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Susan M Bueno
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alejandr A Hidalgo
- Laboratorio de patogénesis molecular y antimicrobianos y Escuela de Química y Farmacia, Universidad Andres Bello, Santiago, Chile
| | - Claudia P Saavedra
- Laboratorio de Microbiología Molecular, Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias de la Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.
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10
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Salvail H, Groisman EA. The phosphorelay BarA/SirA activates the non-cognate regulator RcsB in Salmonella enterica. PLoS Genet 2020; 16:e1008722. [PMID: 32392214 PMCID: PMC7241856 DOI: 10.1371/journal.pgen.1008722] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/21/2020] [Accepted: 03/18/2020] [Indexed: 11/18/2022] Open
Abstract
To survive an environmental stress, organisms must detect the stress and mount an appropriate response. One way that bacteria do so is by phosphorelay systems that respond to a stress by activating a regulator that modifies gene expression. To ensure an appropriate response, a given regulator is typically activated solely by its cognate phosphorelay protein(s). However, we now report that the regulator RcsB is activated by both cognate and non-cognate phosphorelay proteins, depending on the condition experienced by the bacterium Salmonella enterica serovar Typhimurium. The RcsC and RcsD proteins form a phosphorelay that activates their cognate regulator RcsB in response to outer membrane stress and cell wall perturbations, conditions Salmonella experiences during infection. Surprisingly, the non-cognate phosphorelay protein BarA activates RcsB during logarithmic growth in Luria-Bertani medium in three ways. That is, BarA’s cognate regulator SirA promotes transcription of the rcsDB operon; the SirA-dependent regulatory RNAs CsrB and CsrC further increase RcsB-activated gene transcription; and BarA activates RcsB independently of the RcsC, RcsD, and SirA proteins. Activation of a regulator by multiple sensors broadens the spectrum of environments in which a set of genes is expressed without evolving binding sites for different regulators at each of these genes. The phosphorelay is a form of signal transduction used by organisms in all three domains of life. Typically, a phosphorelay consists of sensor proteins that respond to specific signals by activating a cognate regulatory protein that alters gene expression. Phosphorelays exhibit specificity towards their cognate regulators, thereby ensuring that any changes in gene expression help an organism cope with the experienced stress (and not with an unrelated stress). However, we now report that the regulator RcsB is activated by both cognate and non-cognate phosphorelay proteins in the bacterium Salmonella enterica serovar Typhimurium. The phosphorelay proteins RcsC and RcsD activate RcsB upon cell envelope perturbations, whereas the non-cognate phosphorelay protein BarA activates RcsB during rapid growth in Luria-Bertani medium. Our findings establish that BarA controls gene expression via both its cognate regulator SirA and the non-cognate regulator RcsB. In addition, they demonstrate that RcsB controls gene expression in response to multiple signals detected by the RcsC, RcsD, and BarA proteins.
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Affiliation(s)
- Hubert Salvail
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Yale Microbial Sciences Institute, West Haven, Connecticut, United States of America
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Yale Microbial Sciences Institute, West Haven, Connecticut, United States of America
- * E-mail:
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11
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Alwis PA, Treerat P, Gong L, Deveson Lucas D, Allwood EM, Prescott M, Devenish RJ, Adler B, Boyce JD. Disruption of the Burkholderia pseudomallei two-component signal transduction system BbeR-BbeS leads to increased extracellular DNA secretion and altered biofilm formation. Vet Microbiol 2020; 242:108603. [PMID: 32122607 DOI: 10.1016/j.vetmic.2020.108603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 02/03/2020] [Indexed: 10/25/2022]
Abstract
Two-component signal transduction systems (TCSTS) are abundant among prokaryotes and regulate important functions, including drug resistance and virulence. The Gram-negative bacterium Burkholderia pseudomallei, which causes the severe infectious disease melioidosis, encodes 136 putative TCSTS components. In silico analyses of these TCSTS indicated that the predicted BbeR-BbeS system (BPSL1036-BPSL1037) displayed significant amino acid sequence similarity to the Shigella flexneri virulence-associated OmpR-EnvZ osmoregulator. To assess the function of the B. pseudomallei BbeR-BbeS system, we constructed by allelic exchange a ΔbbeRS double mutant strain lacking both genes, and single ΔbbeR and ΔbbeS mutants. All three mutant strains caused disease in the BALB/c acute melioidosis model at the same rate as the wild-type strain, displayed unchanged swarming motility on semi-solid medium, and were unaffected for viability on high-osmolarity media. However, when cultured at 37 °C for at least 14 days, ΔbbeS and ΔbbeR colonies developed a distinct, hypermucoid morphology absent in similarly-cultured wild-type colonies. At both 30 °C and 37 °C, these hypermucoid strains produced wild-type levels of type I capsule but released increased quantities of extracellular DNA (eDNA). Upon static growth in liquid medium, all B. pseudomallei strains produced pellicle biofilms that contained DNA in close association with bacterial cells; however, the ΔbbeS and ΔbbeR strains produced increased biofilms with altered microscopic architecture compared to the wild-type. Unusually, while the ΔbbeS and ΔbbeR single-deletion mutants displayed clear phenotypes, the ΔbbeRS double-deletion mutant was indistinguishable from the wild-type strain. We propose that BbeR-BbeS indirectly affects eDNA secretion and biofilm formation through cross-talk with one or more other TCSTS.
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Affiliation(s)
- Priyangi A Alwis
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Puthayalai Treerat
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Lan Gong
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Deanna Deveson Lucas
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Elizabeth M Allwood
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Mark Prescott
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Rodney J Devenish
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Ben Adler
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - John D Boyce
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia.
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12
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García-Torrico AI, Guijarro JA, Cascales D, Méndez J. Changes in physiology and virulence during the selection of resistant Yersinia ruckeri mutants under subinhibitory cefotaxime concentrations. JOURNAL OF FISH DISEASES 2019; 42:1687-1696. [PMID: 31617230 DOI: 10.1111/jfd.13086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/24/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Bacterial antibiotic resistance is one of the main healthcare problems currently. Apart from reducing antibiotic efficacy, it has awakened the interest of scientists due to its association with bacterial fitness and virulence. Interestingly, antibiotic resistance can be a source of both increased fitness and decreased fitness, even though the molecular basis of these relationships remains unknown. The aim of this work is to define the effects of sub-MIC concentrations of cefotaxime, an antibiotic extensively used in clinical practice, on the physiology and virulence of Yersinia ruckeri and to determine the importance of these sub-MIC concentrations for the selection of antibiotic-resistant mutants in the aquatic environment. Results indicated that exposure to sub-MIC concentrations of cefotaxime selected Y. ruckeri populations with irreversible alterations in the physiology, such as slow growth, aggregation in liquid cultures and modification of the colony morphology. These bacteria also displayed changes in the OMPs and LPS profiles and a full attenuation of virulence. An overexpression of the envelope stress regulator RpoE was also detected after exposure to the antibiotic. In conclusion, exposure to cefotaxime selected, at high frequency, Y. ruckeri strains that survive the antibiotic stress at the expense of a fitness cost and the loss of virulence.
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Affiliation(s)
- Ana Isabel García-Torrico
- Área de Microbiología, Departamento de Biología Funcional, Facultad de Medicina, IUBA, Universidad de Oviedo, Oviedo, Spain
| | - José A Guijarro
- Área de Microbiología, Departamento de Biología Funcional, Facultad de Medicina, IUBA, Universidad de Oviedo, Oviedo, Spain
| | - Desirée Cascales
- Área de Microbiología, Departamento de Biología Funcional, Facultad de Medicina, IUBA, Universidad de Oviedo, Oviedo, Spain
| | - Jessica Méndez
- Área de Microbiología, Departamento de Biología Funcional, Facultad de Medicina, IUBA, Universidad de Oviedo, Oviedo, Spain
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13
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Fajardo-Lubián A, Ben Zakour NL, Agyekum A, Qi Q, Iredell JR. Host adaptation and convergent evolution increases antibiotic resistance without loss of virulence in a major human pathogen. PLoS Pathog 2019; 15:e1007218. [PMID: 30875398 PMCID: PMC6436753 DOI: 10.1371/journal.ppat.1007218] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 03/27/2019] [Accepted: 01/16/2019] [Indexed: 12/19/2022] Open
Abstract
As human population density and antibiotic exposure increase, specialised bacterial subtypes have begun to emerge. Arising among species that are common commensals and infrequent pathogens, antibiotic-resistant 'high-risk clones' have evolved to better survive in the modern human. Here, we show that the major matrix porin (OmpK35) of Klebsiella pneumoniae is not required in the mammalian host for colonisation, pathogenesis, nor for antibiotic resistance, and that it is commonly absent in pathogenic isolates. This is found in association with, but apparently independent of, a highly specific change in the co-regulated partner porin, the osmoporin (OmpK36), which provides enhanced antibiotic resistance without significant loss of fitness in the mammalian host. These features are common in well-described 'high-risk clones' of K. pneumoniae, as well as in unrelated members of this species and similar adaptations are found in other members of the Enterobacteriaceae that share this lifestyle. Available sequence data indicate evolutionary convergence, with implications for the spread of lethal antibiotic-resistant pathogens in humans.
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Affiliation(s)
- Alicia Fajardo-Lubián
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Sydney, New South Wales, Australia
- * E-mail: (AFL); (JRI)
| | - Nouri L. Ben Zakour
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Sydney, New South Wales, Australia
| | - Alex Agyekum
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Sydney, New South Wales, Australia
| | - Qin Qi
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Sydney, New South Wales, Australia
| | - Jonathan R. Iredell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Sydney, New South Wales, Australia
- * E-mail: (AFL); (JRI)
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14
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Abstract
The transport of small molecules across membranes is essential for the import of nutrients and other energy sources into the cell and, for the export of waste and other potentially harmful byproducts out of the cell. While hydrophobic molecules are permeable to membranes, ions and other small polar molecules require transport via specialized membrane transport proteins . The two major classes of membrane transport proteins are transporters and channels. With our focus here on porins-major class of non-specific diffusion channel proteins , we will highlight some recent structural biology reports and functional assays that have substantially contributed to our understanding of the mechanism that mediates uptake of small molecules, including antibiotics, across the outer membrane of Enterobacteriaceae . We will also review advances in the regulation of porin expression and porin biogenesis and discuss these pathways as new therapeutic targets.
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Affiliation(s)
- Muriel Masi
- UMR_MD1, Inserm U1261, IRBA, Membranes et Cibles Thérapeutiques, Facultés de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France
| | | | - Jean-Marie Pagès
- UMR_MD1, Inserm U1261, IRBA, Membranes et Cibles Thérapeutiques, Facultés de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France.
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15
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Pardo-Esté C, Hidalgo AA, Aguirre C, Briones AC, Cabezas CE, Castro-Severyn J, Fuentes JA, Opazo CM, Riedel CA, Otero C, Pacheco R, Valvano MA, Saavedra CP. The ArcAB two-component regulatory system promotes resistance to reactive oxygen species and systemic infection by Salmonella Typhimurium. PLoS One 2018; 13:e0203497. [PMID: 30180204 PMCID: PMC6122832 DOI: 10.1371/journal.pone.0203497] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/21/2018] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica Serovar Typhimurium (S. Typhimurium) is an intracellular bacterium that overcomes host immune system barriers for successful infection. The bacterium colonizes the proximal small intestine, penetrates the epithelial layer, and is engulfed by macrophages and neutrophils. Intracellularly, S. Typhimurium encounters highly toxic reactive oxygen species including hydrogen peroxide and hypochlorous acid. The molecular mechanisms of Salmonella resistance to intracellular oxidative stress is not completely understood. The ArcAB two-component system is a global regulatory system that responds to oxygen. In this work, we show that the ArcA response regulator participates in Salmonella adaptation to changing oxygen levels and is also involved in promoting intracellular survival in macrophages and neutrophils, enabling S. Typhimurium to successfully establish a systemic infection.
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Affiliation(s)
- Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alejandro A. Hidalgo
- Laboratorio de Patogenesis Bacteriana, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Camila Aguirre
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alan C. Briones
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Carolina E. Cabezas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan Castro-Severyn
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan A. Fuentes
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Cecilia M. Opazo
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Claudia A. Riedel
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Carolina Otero
- Center for Integrative Medicine and Innovative Science (CIMIS), Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Rodrigo Pacheco
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Santiago, Chile
- Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Miguel A. Valvano
- The Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Claudia P. Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
- * E-mail:
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16
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Nabergoj D, Modic P, Podgornik A. Effect of bacterial growth rate on bacteriophage population growth rate. Microbiologyopen 2018; 7:e00558. [PMID: 29195013 PMCID: PMC5911998 DOI: 10.1002/mbo3.558] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 01/15/2023] Open
Abstract
It is important to understand how physiological state of the host influence propagation of bacteriophages (phages), due to the potential higher phage production needs in the future. In our study, we tried to elucidate the effect of bacterial growth rate on adsorption constant (δ), latent period (L), burst size (b), and bacteriophage population growth rate (λ). As a model system, a well-studied phage T4 and Escherichia coli K-12 as a host was used. Bacteria were grown in a continuous culture operating at dilution rates in the range between 0.06 and 0.98 hr-1 . It was found that the burst size increases linearly from 8 PFU·cell-1 to 89 PFU·cell-1 with increase in bacteria growth rate. On the other hand, adsorption constant and latent period were both decreasing from 2.6∙10-9 ml·min-1 and 80 min to reach limiting values of 0.5 × 10-9 ml·min-1 and 27 min at higher growth rates, respectively. Both trends were mathematically described with Michaelis-Menten based type of equation and reasons for such form are discussed. By applying selected equations, a mathematical equation for prediction of bacteriophage population growth rate as a function of dilution rate was derived, reaching values around 8 hr-1 at highest dilution rate. Interestingly, almost identical description can be obtained using much simpler Monod type equation and possible reasons for this finding are discussed.
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Affiliation(s)
- Dominik Nabergoj
- Center of Excellence for BiosensorsInstrumentation and Process Control ‐ COBIKAjdovščinaSlovenia
| | - Petra Modic
- Faculty of Chemistry and Chemical TechnologyUniversity of LjubljanaLjubljanaSlovenia
| | - Aleš Podgornik
- Center of Excellence for BiosensorsInstrumentation and Process Control ‐ COBIKAjdovščinaSlovenia
- Faculty of Chemistry and Chemical TechnologyUniversity of LjubljanaLjubljanaSlovenia
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17
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Lee YH, Kim JH. Direct interaction between the transcription factors CadC and OmpR involved in the acid stress response of Salmonella enterica. J Microbiol 2017; 55:966-972. [DOI: 10.1007/s12275-017-7410-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/18/2017] [Accepted: 10/23/2017] [Indexed: 01/12/2023]
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18
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Solov'eva T, Likhatskaya G, Khomenko V, Guzev K, Kim N, Bystritskaya E, Novikova O, Stenkova A, Rakin A, Isaeva M. The impact of length variations in the L2 loop on the structure and thermal stability of non-specific porins: The case of OmpCs from the Yersinia pseudotuberculosis complex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:515-525. [PMID: 29038023 DOI: 10.1016/j.bbamem.2017.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 09/25/2017] [Accepted: 10/11/2017] [Indexed: 10/18/2022]
Abstract
Porins are integral proteins of the outer membranes of gram-negative bacteria. In membranes, they exist as homotrimers and the L2 loops contribute to their stability. Comparison of OmpC porins of the Yersinia pseudotuberculosis complex with other enterobacterial porins demonstrated L2 loop length diversity, which is caused by varying numbers of dipeptide/tripeptide repeats. The OmpC porins are highly homologous to each other, and they can be subdivided into five isoforms based on their L2 loop structure. Optical spectroscopy and SDS-PAGE experiments revealed that particularities of the L2 loops affected the structure and thermal stability of the porins. Thermal denaturation studies showed that porins with shorter loops, compared to porins with longer loops, had more stable tertiary and less stable secondary and quaternary structures. According to our comparative modeling results, the L2 loops differ in their structure by adopting different spatial positions and forming different polar bonds with a neighbor monomer. The replacement of asparagine with arginine at the C-terminus of the L2 loop shifts the loop upwards and causes the loss of contacts with the arginine clusters within the pores. The increase in the length of these loops ensures that they shift down toward the pore and restore their contacts with arginines on the channel wall, as is the case in classical nonspecific porins. Despite the fact that the surface charge density varies considerably among the OmpC porins, the L2 loops form a typical negatively charged region in the center of the trimer.
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Affiliation(s)
- T Solov'eva
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - G Likhatskaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - V Khomenko
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - K Guzev
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - N Kim
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - E Bystritskaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - O Novikova
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - A Stenkova
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia
| | - A Rakin
- Institute for Bacterial Infections and Zoonoses, Federal Research Institute for Animal Health, Naumburger Str. 96 a, 07743 Jena, Germany
| | - M Isaeva
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry FEB RAS, 690022 Prospect 100-let Vladivostoku 159, Vladivostok, Russia.
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19
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Guckes KR, Breland EJ, Zhang EW, Hanks SC, Gill NK, Algood HMS, Schmitz JE, Stratton CW, Hadjifrangiskou M. Signaling by two-component system noncognate partners promotes intrinsic tolerance to polymyxin B in uropathogenic Escherichia coli. Sci Signal 2017; 10:10/461/eaag1775. [PMID: 28074004 PMCID: PMC5677524 DOI: 10.1126/scisignal.aag1775] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bacteria use two-component systems (TCSs) to react appropriately to environmental stimuli. Typical TCSs comprise a sensor histidine kinase that acts as a receptor coupled to a partner response regulator that coordinates changes in bacterial behavior, often through its activity as a transcriptional regulator. TCS interactions are typically confined to cognate pairs of histidine kinases and response regulators. We describe two distinct TCSs in uropathogenic Escherichia coli (UPEC) that interact to mediate a response to ferric iron. The PmrAB and QseBC TCSs were both required for proper transcriptional response to ferric iron. Ferric iron induced the histidine kinase PmrB to phosphotransfer to both its cognate response regulator PmrA and the noncognate response regulator QseB, leading to transcriptional responses coordinated by both regulators. Pretreatment of the UPEC strain UTI89 with ferric iron led to increased resistance to polymyxin B that required both PmrA and QseB. Similarly, pretreatment of several UPEC isolates with ferric iron increased tolerance to polymyxin B. This study defines physiologically relevant cross talk between TCSs in a bacterial pathogen and provides a potential mechanism for antibiotic resistance of some strains of UPEC.
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Affiliation(s)
- Kirsten R Guckes
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Erin J Breland
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ellisa W Zhang
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | | | - Holly M S Algood
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Veterans Affairs Tennessee Valley Healthcare Services, Nashville, TN 37212, USA
| | - Jonathan E Schmitz
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Charles W Stratton
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Maria Hadjifrangiskou
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA. .,Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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20
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Agrawal R, Sahoo BK, Saini DK. Cross-talk and specificity in two-component signal transduction pathways. Future Microbiol 2016; 11:685-97. [PMID: 27159035 DOI: 10.2217/fmb-2016-0001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two-component signaling systems (TCSs) are composed of two proteins, sensor kinases and response regulators, which can cross-talk and integrate information between them by virtue of high-sequence conservation and modular nature, to generate concerted and diversified responses. However, TCSs have been shown to be insulated, to facilitate linear signal transmission and response generation. Here, we discuss various mechanisms that confer specificity or cross-talk among TCSs. The presented models are supported with evidence that indicate the physiological significance of the observed TCS signaling architecture. Overall, we propose that the signaling topology of any TCSs cannot be predicted using obvious sequence or structural rules, as TCS signaling is regulated by multiple factors, including spatial and temporal distribution of the participating proteins.
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Affiliation(s)
- Ruchi Agrawal
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, India
| | - Bikash Kumar Sahoo
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, India
| | - Deepak Kumar Saini
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, India.,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
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21
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Functional Dissection of the CroRS Two-Component System Required for Resistance to Cell Wall Stressors in Enterococcus faecalis. J Bacteriol 2016; 198:1326-36. [PMID: 26883822 DOI: 10.1128/jb.00995-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/05/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Bacteria use two-component signal transduction systems (TCSs) to sense and respond to environmental changes via a conserved phosphorelay between a sensor histidine kinase and its cognate response regulator. The opportunistic pathogen Enterococcus faecalis utilizes a TCS comprised of the histidine kinase CroS and the response regulator CroR to mediate resistance to cell wall stresses such as cephalosporin antibiotics, but the molecular details by which CroRS promotes cephalosporin resistance have not been elucidated. Here, we analyzed mutants of E. faecalis carrying substitutions in CroR and CroS to demonstrate that phosphorylated CroR drives resistance to cephalosporins, and that CroS exhibits kinase and phosphatase activities to control the level of CroR phosphorylation in vivo. Deletion of croS in various lineages of E. faecalis revealed a CroS-independent mechanism for CroR phosphorylation and led to the identification of a noncognate histidine kinase capable of influencing CroR (encoded by OG1RF_12162; here called cisS). Further analysis of this TCS network revealed that both systems respond to cell wall stress. IMPORTANCE TCSs allow bacteria to sense and respond to many different environmental conditions. The opportunistic pathogen Enterococcus faecalis utilizes the CroRS TCS to mediate resistance to cell wall stresses, including clinically relevant antibiotics such as cephalosporins and glycopeptides. In this study, we use genetic and biochemical means to investigate the relationship between CroRS signaling and cephalosporin resistance in E. faecalis cells. Through this, we uncovered a signaling network formed between the CroRS TCS and a previously uncharacterized TCS that also responds to cell wall stress. This study provides mechanistic insights into CroRS signaling and cephalosporin resistance in E. faecalis.
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22
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Marcus EA, Sachs G, Wen Y, Scott DR. Phosphorylation-dependent and Phosphorylation-independent Regulation of Helicobacter pylori Acid Acclimation by the ArsRS Two-component System. Helicobacter 2016; 21:69-81. [PMID: 25997502 PMCID: PMC4655181 DOI: 10.1111/hel.12235] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND The pH-sensitive Helicobacter pylori ArsRS two-component system (TCS) aids survival of this neutralophile in the gastric environment by directly sensing and responding to environmental acidity. ArsS is required for acid-induced trafficking of urease and its accessory proteins to the inner membrane, allowing rapid, urea-dependent cytoplasmic and periplasmic buffering. Expression of ArsR, but not its phosphorylation, is essential for bacterial viability. The aim of this study was to characterize the roles of ArsS and ArsR in the response of H. pylori to acid. MATERIALS AND METHODS Wild-type H. pylori and an arsR(D52N) phosphorylation-deficient strain were incubated at acidic or neutral pH. Gene and protein expression, survival, membrane trafficking of urease proteins, urease activity, and internal pH were studied. RESULTS Phosphorylation of ArsR is not required for acid survival. ArsS-driven trafficking of urease proteins to the membrane in acid, required for recovery of internal pH, is independent of ArsR phosphorylation. ArsR phosphorylation increases expression of the urease gene cluster, and the loss of negative feedback in a phosphorylation-deficient mutant leads to an increase in total urease activity. CONCLUSIONS ArsRS has a dual function in acid acclimation: regulation of urease trafficking to UreI at the cytoplasmic membrane, driven by ArsS, and regulation of urease gene cluster expression, driven by phosphorylation of ArsR. ArsS and ArsR work through phosphorylation-dependent and phosphorylation-independent regulatory mechanisms to impact acid acclimation and allow gastric colonization. Furthering understanding of the intricacies of acid acclimation will impact the future development of targeted, nonantibiotic treatment regimens.
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Affiliation(s)
- Elizabeth A. Marcus
- Department of Pediatrics, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
| | - George Sachs
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA
- Department of Medicine, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
| | - Yi Wen
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
| | - David R. Scott
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
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23
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Nguyen MP, Yoon JM, Cho MH, Lee SW. Prokaryotic 2-component systems and the OmpR/PhoB superfamily. Can J Microbiol 2015; 61:799-810. [DOI: 10.1139/cjm-2015-0345] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In bacteria, 2-component regulatory systems (TCSs) are the critical information-processing pathways that link stimuli to specific adaptive responses. Signals perceived by membrane sensors, which are generally histidine kinases, are transmitted by response regulators (RRs) to allow cells to cope rapidly and effectively with environmental challenges. Over the past few decades, genes encoding components of TCSs and their responsive proteins have been identified, crystal structures have been described, and signaling mechanisms have been elucidated. Here, we review recent findings and interesting breakthroughs in bacterial TCS research. Furthermore, we discuss structural features, mechanisms of activation and regulation, and cross-regulation of RRs, with a focus on the largest RR family, OmpR/PhoB, to provide a comprehensive overview of these critically important signaling molecules.
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Affiliation(s)
| | - Joo-Mi Yoon
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
| | - Man-Ho Cho
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
| | - Sang-Won Lee
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
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Fröhlich H. biRte: Bayesian inference of context-specific regulator activities and transcriptional networks. Bioinformatics 2015; 31:3290-8. [PMID: 26112290 DOI: 10.1093/bioinformatics/btv379] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/15/2015] [Indexed: 11/14/2022] Open
Abstract
UNLABELLED In the last years there has been an increasing effort to computationally model and predict the influence of regulators (transcription factors, miRNAs) on gene expression. Here we introduce biRte as a computationally attractive approach combining Bayesian inference of regulator activities with network reverse engineering. biRte integrates target gene predictions with different omics data entities (e.g. miRNA and mRNA data) into a joint probabilistic framework. The utility of our method is tested in extensive simulation studies and demonstrated with applications from prostate cancer and Escherichia coli growth control. The resulting regulatory networks generally show a good agreement with the biological literature. AVAILABILITY AND IMPLEMENTATION biRte is available on Bioconductor (http://bioconductor.org). CONTACT frohlich@bit.uni-bonn.de SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Holger Fröhlich
- University of Bonn, Institute for Computer Science, Römerstr. 164, 53117 Bonn, Germany
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25
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The two-component signalling networks of Mycobacterium tuberculosis display extensive cross-talk in vitro. Biochem J 2015; 469:121-34. [DOI: 10.1042/bj20150268] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/01/2015] [Indexed: 02/06/2023]
Abstract
Bacteria use two-component signalling systems (TCSs) to sense and respond to environmental changes. Currently, they are thought to be highly specific, with each TCS functioning independently. Here, unlike the prevalent paradigm, we show that the TCSs of M. tuberculosis cross-talk extensively, thereby proposing an alternative signalling scenario.
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Bielecki P, Jensen V, Schulze W, Gödeke J, Strehmel J, Eckweiler D, Nicolai T, Bielecka A, Wille T, Gerlach RG, Häussler S. Cross talk between the response regulators PhoB and TctD allows for the integration of diverse environmental signals in Pseudomonas aeruginosa. Nucleic Acids Res 2015; 43:6413-25. [PMID: 26082498 PMCID: PMC4513871 DOI: 10.1093/nar/gkv599] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 05/25/2015] [Indexed: 01/08/2023] Open
Abstract
Two-component systems (TCS) serve as stimulus-response coupling mechanisms to allow organisms to adapt to a variety of environmental conditions. The opportunistic pathogen Pseudomonas aeruginosa encodes for more than 100 TCS components. To avoid unwanted cross-talk, signaling cascades are very specific, with one sensor talking to its cognate response regulator (RR). However, cross-regulation may provide means to integrate different environmental stimuli into a harmonized output response. By applying a split luciferase complementation assay, we identified a functional interaction of two RRs of the OmpR/PhoB subfamily, namely PhoB and TctD in P. aeruginosa. Transcriptional profiling, ChIP-seq analysis and a global motif scan uncovered the regulons of the two RRs as well as a quadripartite binding motif in six promoter regions. Phosphate limitation resulted in PhoB-dependent expression of the downstream genes, whereas the presence of TctD counteracted this activation. Thus, the integration of two important environmental signals e.g. phosphate availability and the carbon source are achieved by a titration of the relative amounts of two phosphorylated RRs that inversely regulate a common subset of genes. In conclusion, our results on the PhoB and TctD mediated two-component signal transduction pathways exemplify how P. aeruginosa may exploit cross-regulation to adapt bacterial behavior to complex environments.
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Affiliation(s)
- Piotr Bielecki
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany
| | - Vanessa Jensen
- Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany
| | - Wiebke Schulze
- Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany
| | - Julia Gödeke
- Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany
| | - Janine Strehmel
- Department of Molecular Bacteriology; Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
| | - Denitsa Eckweiler
- Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany Department of Molecular Bacteriology; Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
| | - Tanja Nicolai
- Department of Molecular Bacteriology; Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
| | - Agata Bielecka
- Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany Department of Molecular Bacteriology; Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
| | - Thorsten Wille
- Junior Research Group 3, Robert Koch-Institute, Wernigerode Branch, Burgstrasse 37, 38855 Wernigerode, Germany
| | - Roman G Gerlach
- Junior Research Group 3, Robert Koch-Institute, Wernigerode Branch, Burgstrasse 37, 38855 Wernigerode, Germany
| | - Susanne Häussler
- Institute of Molecular Bacteriology, TWINCORE GmbH, Centre for Clinical and Experimental Infection Research, a joint venture of the Hannover Medical School and the Helmholtz Centre for Infection Research, Feodor-Lynen-Strasse 7, 30625 Hannover, Germany Department of Molecular Bacteriology; Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
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Two-component system cross-regulation integrates Bacillus anthracis response to heme and cell envelope stress. PLoS Pathog 2014; 10:e1004044. [PMID: 24675902 PMCID: PMC3968170 DOI: 10.1371/journal.ppat.1004044] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 02/06/2014] [Indexed: 11/30/2022] Open
Abstract
Two-component signaling systems (TCSs) are one of the mechanisms that bacteria employ to sense and adapt to changes in the environment. A prototypical TCS functions as a phosphorelay from a membrane-bound sensor histidine kinase (HK) to a cytoplasmic response regulator (RR) that controls target gene expression. Despite significant homology in the signaling domains of HKs and RRs, TCSs are thought to typically function as linear systems with little to no cross-talk between non-cognate HK-RR pairs. Here we have identified several cell envelope acting compounds that stimulate a previously uncharacterized Bacillus anthracis TCS. Furthermore, this TCS cross-signals with the heme sensing TCS HssRS; therefore, we have named it HssRS interfacing TCS (HitRS). HssRS reciprocates cross-talk to HitRS, suggesting a link between heme toxicity and cell envelope stress. The signaling between HssRS and HitRS occurs in the parental B. anthracis strain; therefore, we classify HssRS-HitRS interactions as cross-regulation. Cross-talk between HssRS and HitRS occurs at both HK-RR and post-RR signaling junctions. Finally, HitRS also regulates a previously unstudied ABC transporter implicating this transporter in the response to cell envelope stress. This chemical biology approach to probing TCS signaling provides a new model for understanding how bacterial signaling networks are integrated to enable adaptation to complex environments such as those encountered during colonization of the vertebrate host. The vertebrate host is a hostile environment to microbes, where large variations in temperature, oxygen, and nutrient availability challenge microbial replication. In order to successfully infect vertebrates, pathogens must sense that they have entered their host and alter gene expression accordingly. One way bacteria adapt to their environment is by using two-component signaling systems (TCS), which are comprised of a signal sensor and a transcriptional regulator. The core signaling components of TCSs are conserved across the bacterial Kingdom; however, examples of interactions between two distinct TCS are extremely rare. Here we have probed how Bacillus anthracis, the causative agent of anthrax, adapts to life in the vertebrate host. The B. anthracis heme sensing TCS, HssRS, senses heme as a component of vertebrate blood and protects the bacteria from heme toxicity. We have identified a new TCS (HitRS), which is activated by compounds that alter the integrity of the cell envelope, and interacts with HssRS to coordinate a simultaneous response to both heme and cell envelope stress. This reciprocal HssRS-HitRS signaling is an unusual demonstration of bacterial signal cross-regulation and suggests that coordinating the response to heme and cell envelope stress is important for B. anthracis adaptation to the vertebrate host.
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Park DM, Akhtar MS, Ansari AZ, Landick R, Kiley PJ. The bacterial response regulator ArcA uses a diverse binding site architecture to regulate carbon oxidation globally. PLoS Genet 2013; 9:e1003839. [PMID: 24146625 PMCID: PMC3798270 DOI: 10.1371/journal.pgen.1003839] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/13/2013] [Indexed: 12/02/2022] Open
Abstract
Despite the importance of maintaining redox homeostasis for cellular viability, how cells control redox balance globally is poorly understood. Here we provide new mechanistic insight into how the balance between reduced and oxidized electron carriers is regulated at the level of gene expression by mapping the regulon of the response regulator ArcA from Escherichia coli, which responds to the quinone/quinol redox couple via its membrane-bound sensor kinase, ArcB. Our genome-wide analysis reveals that ArcA reprograms metabolism under anaerobic conditions such that carbon oxidation pathways that recycle redox carriers via respiration are transcriptionally repressed by ArcA. We propose that this strategy favors use of catabolic pathways that recycle redox carriers via fermentation akin to lactate production in mammalian cells. Unexpectedly, bioinformatic analysis of the sequences bound by ArcA in ChIP-seq revealed that most ArcA binding sites contain additional direct repeat elements beyond the two required for binding an ArcA dimer. DNase I footprinting assays suggest that non-canonical arrangements of cis-regulatory modules dictate both the length and concentration-sensitive occupancy of DNA sites. We propose that this plasticity in ArcA binding site architecture provides both an efficient means of encoding binding sites for ArcA, σ(70)-RNAP and perhaps other transcription factors within the same narrow sequence space and an effective mechanism for global control of carbon metabolism to maintain redox homeostasis.
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Affiliation(s)
- Dan M. Park
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Md. Sohail Akhtar
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Aseem Z. Ansari
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Bacteriology; University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Patricia J. Kiley
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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Morales EH, Calderón IL, Collao B, Gil F, Porwollik S, McClelland M, Saavedra CP. Hypochlorous acid and hydrogen peroxide-induced negative regulation of Salmonella enterica serovar Typhimurium ompW by the response regulator ArcA. BMC Microbiol 2012; 12:63. [PMID: 22545862 PMCID: PMC3358236 DOI: 10.1186/1471-2180-12-63] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 04/30/2012] [Indexed: 11/29/2022] Open
Abstract
Background Hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) are reactive oxygen species that are part of the oxidative burst encountered by Salmonella enterica serovar Typhimurium (S. Typhimurium) upon internalization by phagocytic cells. In order to survive, bacteria must sense these signals and modulate gene expression. Growing evidence indicates that the ArcAB two component system plays a role in the resistance to reactive oxygen species. We investigated the influx of H2O2 and HOCl through OmpW and the role of ArcAB in modulating its expression after exposure to both toxic compounds in S. Typhimurium. Results H2O2 and HOCl influx was determined both in vitro and in vivo. A S. Typhimurium ompW mutant strain (∆ompW) exposed to sub-lethal levels of H2O2 and HOCl showed a decreased influx of both compounds as compared to a wild type strain. Further evidence of H2O2 and HOCl diffusion through OmpW was obtained by using reconstituted proteoliposomes. We hypothesized that ompW expression should be negatively regulated upon exposure to H2O2 and HOCl to better exclude these compounds from the cell. As expected, qRT-PCR showed a negative regulation in a wild type strain treated with sub-lethal concentrations of these compounds. A bioinformatic analysis in search for potential negative regulators predicted the presence of three ArcA binding sites at the ompW promoter region. By electrophoretic mobility shift assay (EMSA) and using transcriptional fusions we demonstrated an interaction between ArcA and one site at the ompW promoter region. Moreover, qRT-PCR showed that the negative regulation observed in the wild type strain was lost in an arcA and in arcB mutant strains. Conclusions OmpW allows the influx of H2O2 and HOCl and is negatively regulated by ArcA by direct interaction with the ompW promoter region upon exposure to both toxic compounds.
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Affiliation(s)
- Eduardo H Morales
- Laboratorio de Microbiología Molecular, Facultad Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile
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Zacher B, Abnaof K, Gade S, Younesi E, Tresch A, Fröhlich H. Joint Bayesian inference of condition-specific miRNA and transcription factor activities from combined gene and microRNA expression data. ACTA ACUST UNITED AC 2012; 28:1714-20. [PMID: 22563068 DOI: 10.1093/bioinformatics/bts257] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
MOTIVATION There have been many successful experimental and bioinformatics efforts to elucidate transcription factor (TF)-target networks in several organisms. For many organisms, these annotations are complemented by miRNA-target networks of good quality. Attempts that use these networks in combination with gene expression data to draw conclusions on TF or miRNA activity are, however, still relatively sparse. RESULTS In this study, we propose Bayesian inference of regulation of transcriptional activity (BIRTA) as a novel approach to infer both, TF and miRNA activities, from combined miRNA and mRNA expression data in a condition specific way. That means our model explains mRNA and miRNA expression for a specific experimental condition by the activities of certain miRNAs and TFs, hence allowing for differentiating between switches from active to inactive (negative switch) and inactive to active (positive switch) forms. Extensive simulations of our model reveal its good prediction performance in comparison to other approaches. Furthermore, the utility of BIRTA is demonstrated at the example of Escherichia coli data comparing aerobic and anaerobic growth conditions, and by human expression data from pancreas and ovarian cancer. AVAILABILITY AND IMPLEMENTATION The method is implemented in the R package birta, which is freely available for Bio-conductor (>=2.10) on http://www.bioconductor.org/packages/release/bioc/html/birta.html.
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Affiliation(s)
- Benedikt Zacher
- Ludwig-Maximilians-Universität München, Gene Center Munich and Center for integrated Protein Science CiPSM, Department of Chemistry and Biochemistry, Feodor-Lynen-Street 25, 81377 Munich, Germany
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The LovK-LovR two-component system is a regulator of the general stress pathway in Caulobacter crescentus. J Bacteriol 2012; 194:3038-49. [PMID: 22408156 DOI: 10.1128/jb.00182-12] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A conserved set of regulators control the general stress response in Caulobacter crescentus, including σ(T), its anti-σ factor NepR, the anti-anti-σ factor PhyR, and the transmembrane sensor kinase PhyK. We report that the soluble histidine kinase LovK and the single-domain response regulator LovR also function within the C. crescentus general stress pathway. Our genetic data support a model in which LovK-LovR functions upstream of σ(T) by controlling the phosphorylation state and thus anti-anti-σ activity of PhyR. Transcription of lovK and lovR is independently activated by stress through a mechanism that requires sigT and phyR. Conversely, lovK and lovR function together to repress transcription of the general stress regulon. Concordant with a functional role of the LovK-LovR two-component system as a negative regulator of the general stress pathway, lovK-lovR-null mutants exhibit increased cell survival after osmotic stress, while coordinate overexpression of lovK and lovR attenuates cell survival relative to that of the wild type. Notably, lovK can complement the transcriptional and cell survival defects of a phyK-null mutant when lovR is deleted. Moreover, in this same genetic background, σ(T)-dependent transcription is activated in response to osmotic stress. This result suggests that flavin-binding LOV (light, oxygen, or voltage) histidine kinases are competent to perceive cytoplasmic signals in addition to the environmental signal blue light. We conclude that the PhyK-PhyR and LovK-LovR two-component signaling systems coordinately regulate stress physiology in C. crescentus.
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Yuan J, Wei B, Shi M, Gao H. Functional assessment of EnvZ/OmpR two-component system in Shewanella oneidensis. PLoS One 2011; 6:e23701. [PMID: 21886811 PMCID: PMC3160321 DOI: 10.1371/journal.pone.0023701] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 07/22/2011] [Indexed: 11/23/2022] Open
Abstract
EnvZ and OmpR constitute the bacterial two-component signal transduction system known to mediate osmotic stress response in a number of Gram-negative bacteria. In an effort to understand the mechanism through which Shewanella oneidensis senses and responds to environmental osmolarity changes, structure of the ompR-envZ operon was determined with Northern blotting assay and roles of the EnvZ/OmpR two-component system in response to various stresses were investigated with mutational analysis, quantitative reverse transcriptase PCR (qRT-PCR), and phenotype microarrays. Results from the mutational analysis and qRT-PCR suggested that the EnvZ/OmpR system contributed to osmotic stress response of S. oneidensis and very likely engaged a similar strategy employed by E. coli, which involved reciprocal regulation of two major porin coding genes. Additionally, the ompR-envZ system was also found related to cell motility. We further showed that the ompR-envZ dependent regulation of porin genes and motility resided almost completely on ompR and only partially on envZ, indicating additional mechanisms for OmpR phosphorylation. In contrast to E. coli lacking ompR-envZ, however, growth of S. oneidensis did not show a significant dependence on ompR-envZ even under osmotic stress. Further analysis with phenotype microarrays revealed that the S. oneidensis strains lacking a complete ompR-envZ system displayed hypersensitivities to a number of agents, especially in alkaline environment. Taken together, our results suggest that the function of the ompR-envZ system in S. oneidensis, although still connected with osmoregulation, has diverged considerably from that of E. coli. Additional mechanism must exist to support growth of S. oneidensis under osmotic stress.
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Affiliation(s)
- Jie Yuan
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Buyun Wei
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Miaomiao Shi
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Haichun Gao
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- * E-mail:
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Camsund D, Lindblad P, Jaramillo A. Genetically engineered light sensors for control of bacterial gene expression. Biotechnol J 2011; 6:826-36. [PMID: 21648094 DOI: 10.1002/biot.201100091] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2011] [Revised: 04/11/2011] [Accepted: 04/18/2011] [Indexed: 12/28/2022]
Abstract
Light of different wavelengths can serve as a transient, noninvasive means of regulating gene expression for biotechnological purposes. Implementation of advanced gene regulatory circuits will require orthogonal transcriptional systems that can be simultaneously controlled and that can produce several different control states. Fully genetically encoded light sensors take advantage of the favorable characteristics of light, do not need the supplementation of any chemical inducers or co-factors, and have been demonstrated to control gene expression in Escherichia coli. Herein, we review engineered light-sensor systems with potential for in vivo regulation of gene expression in bacteria, and highlight different means of extending the range of available light input and transcriptional output signals. Furthermore, we discuss advances in multiplexing different light sensors for achieving multichromatic control of gene expression and indicate developments that could facilitate the construction of efficient systems for light-regulated, multistate control of gene expression.
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Affiliation(s)
- Daniel Camsund
- Department of Photochemistry and Molecular Science, Uppsala University, Ångström Laboratories, Uppsala, Sweden
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The expression levels of outer membrane proteins STM1530 and OmpD, which are influenced by the CpxAR and BaeSR two-component systems, play important roles in the ceftriaxone resistance of Salmonella enterica serovar Typhimurium. Antimicrob Agents Chemother 2011; 55:3829-37. [PMID: 21646491 DOI: 10.1128/aac.00216-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Significant increases in STM3031, STM1530, and AcrD protein levels and significant decreases in OmpC and OmpD protein levels are present when the ceftriaxone-resistant Salmonella enterica serovar Typhimurium R200 strain is compared with the ceftriaxone-susceptible strain 01-4. AcrD is known to be involved in drug export, and STM3031 seems to play a key role in ceftriaxone resistance. Here, we examine the roles of STM1530, OmpC, and OmpD in ceftriaxone resistance. An ompD gene deletion mutant showed 4-fold higher ceftriaxone resistance than 01-4. An ompC gene deletion mutant showed 4-fold higher cephalothin and erythromycin resistance than 01-4, but there was no effect on ceftriaxone resistance. However, a stm1530 deletion mutant did show >64-fold lower ceftriaxone resistance than R200. Moreover, the STM3031 protein was significantly decreased in R200(Δstm1530) compared to R200. STM3031 expression has been shown to be influenced by the two-component system regulator gene baeR. CpxR seems to modulate BaeR. A cpxA-cpxR gene deletion mutant showed >2,048-fold lower ceftriaxone resistance than R200. The outer membrane protein profile of R200(ΔcpxAR) showed significant decreases in STM3031 and STM1530 compared to R200, while OmpD had returned to the level found in 01-4. Furthermore, the stm3031, stm1530, and ompD mRNA levels were correlated with their protein expression levels in these strains, while decreases in the mRNA levels of the efflux pump acrB, acrD, and acrF genes were found in R200(ΔcpxAR). Findings similar to those for R200(ΔcpxAR) were found for R200(ΔbaeSR). These results, together with those for STM3031 and the fact that STM1530 is an outer membrane protein, suggest that STM1530 and OmpD are influenced by the CpxAR and BaeSR two-component systems and that this contributes to S. enterica serovar Typhimurium ceftriaxone resistance.
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Biochemical characterization of plant hormone cytokinin-receptor histidine kinases using microorganisms. Methods Enzymol 2010; 471:335-56. [PMID: 20946856 DOI: 10.1016/s0076-6879(10)71018-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Results of recent studies on the model higher plant Arabidopsis thaliana have led us to learn about the generality and versatility of two-component systems (TCS) in eukaryotes. In the plant, TCS are crucially involved in certain signal transduction mechanisms underlying the regulation of plant development in response to a subset of plant hormones, namely, cytokinin and ethylene. Results of extensive plant genomics revealed that these hormone-responsive TCS are evolutionarily conserved in many other plants, including mosses, grasses, crops, and trees. In particular, the conserved cytokinin-responsive TCS is typical in the sense that the signaling pathway consists of cytokinin-receptor histidine kinases (HK), histidine-containing phosphotransfer (HPt) factors, and downstream phosphoaccepting response regulators (RR), which together act as His-to-Asp multistep phosphorelay components, and which together modulate the downstream network of cytokinin-responsive gene regulation. The ethylene-responsive TCS is atypical in that ethylene-receptor HKs appear to directly interact with the downstream mitogen-activated protein kinase (MAPK) cascade. The ethylene-responsive HKs have already been introduced in the previous edition of Methods in Enzymology [Schaller, G. E., and Binder, B. M. (2007). Biochemical characterization of plant ethylene receptors following transgenic expression in yeast. Methods Enzymol. 422, 270-287]. Hence, here we focus on the cytokinin-receptor HKs, which are capable of functioning in microorganisms, such as Escherichia coli and Saccharomyces cerevisiae. Some versatile protocols useful for analyzing plant TCS factors by employing these microorganisms will be introduced.
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Lee B, Schramm A, Jagadeesan S, Higgs PI. Two-Component Systems and Regulation of Developmental Progression in Myxococcus xanthus. Methods Enzymol 2010; 471:253-78. [DOI: 10.1016/s0076-6879(10)71014-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Jagadeesan S, Mann P, Schink CW, Higgs PI. A novel "four-component" two-component signal transduction mechanism regulates developmental progression in Myxococcus xanthus. J Biol Chem 2009; 284:21435-45. [PMID: 19535336 PMCID: PMC2755868 DOI: 10.1074/jbc.m109.033415] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Histidine-aspartate phosphorelays are employed by two-component signal transduction family proteins to mediate responses to specific signals or stimuli in microorganisms and plants. The RedCDEF proteins constitute a novel signaling system in which four two-component proteins comprising a histidine kinase, a histidine-kinase like protein, and two response regulators function together to regulate progression through the elaborate developmental program of Myxococcus xanthus. A combination of in vivo phenotypic analyses of in-frame deletions and non-functional point mutations in each gene as well as in vitro autophosphorylation and phosphotransfer analyses of recombinant proteins indicate that the RedC histidine kinase protein autophosphorylates and donates a phosphoryl group to the single domain response regulator, RedF, to repress progression through the developmental program. To relieve this developmental repression, RedC instead phosphorylates RedD, a dual receiver response regulator protein. Surprisingly, RedD transfers the phosphoryl group to the histidine kinase-like protein RedE, which itself appears to be incapable of autophosphorylation. Phosphorylation of RedE may render RedE accessible to RedF, where it removes the phosphoryl group from RedF-P, which is otherwise an unusually stable phosphoprotein. These analyses reveal a novel "four-component" signaling mechanism that has probably arisen to temporally coordinate signals controlling the developmental program in M. xanthus. The RedCDEF signaling system provides an important example of how the inherent plasticity and modularity of the basic two-component signaling domains comprise a highly adaptable framework well suited to expansion into complex signaling mechanisms.
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Affiliation(s)
- Sakthimala Jagadeesan
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
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Yan Q, Gao W, Wu XG, Zhang LQ. Regulation of the PcoI/PcoR quorum-sensing system in Pseudomonas fluorescens 2P24 by the PhoP/PhoQ two-component system. Microbiology (Reading) 2009; 155:124-133. [DOI: 10.1099/mic.0.020750-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A quorum-sensing locus, pcoI/pcoR, which is involved in the regulation of root colonization and plant disease-suppressive ability, was previously identified in Pseudomonas fluorescens 2P24. In this study, we performed random mutagenesis using mini-Tn5 in order to screen the upstream transcriptional regulators of pcoI, a biosynthase gene responsible for the synthesis of N-acylhomoserine lactone signal molecules. Two mutants, PM400 and PM410, with elevated pcoI gene promoter activity, were identified from ∼10 000 insertion clones. The amino acid sequences of the interrupted genes in these two mutants were highly similar to PhoQ, a sensor protein of the two-component regulatory system PhoP/PhoQ, which responds to environmental Mg2+ starvation and regulates virulence in Salmonella typhimurium and antimicrobial peptide resistance in Pseudomonas aeruginosa. The promoter activity of pcoI was also induced under low-Mg2+ conditions in the 2P24 strain of P. fluorescens. Deletion mutagenesis and complementation experiments demonstrated that the transcription of pcoI was negatively regulated by the sensor PhoQ but positively regulated by the response regulator PhoP. Genetic evidence also indicated that transcription of the outer-membrane protein gene oprH was induced by Mg2+ starvation through regulation of the wild-type PhoP/PhoQ system. Additionally, PhoQ was involved in biofilm formation by 2P24 under low-Mg2+ conditions through a PhoP-independent pathway.
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Affiliation(s)
- Qing Yan
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Wei Gao
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Xiao-Gang Wu
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Li-Qun Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
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Mahdiuni H, Mobasheri H, Shafiee A, Foroumadi A. Effects of novel antituberculosis agents on OmpF channel activity. Biochem Biophys Res Commun 2008; 376:174-9. [PMID: 18762173 DOI: 10.1016/j.bbrc.2008.08.113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 08/23/2008] [Indexed: 11/18/2022]
Abstract
Nanopore forming proteins spanning the outer membrane mediate in the diffusion of hydrophilic chemicals through the hydrophobic bacterial cell wall. In this study, the effects of two novel anti-TB derivatives, ethyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio] acetates and propyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio] acetates, on OmpF channel reconstituted in artificial bilayers were evaluated by voltage clamp technique. Surprisingly, ethyl derivative (MIC > or = 6.75 microg/ml) showed no effects on OmpF channel activity but the propyl derivative (MIC=0.39 microg/ml) reduced the channel conductance considerably and changed the gating pattern of the channel. The findings obtained here at molecular level, might shed light on better understanding of the actual mechanism(s) by which the novel anti-TB agents permeate through the cell wall of the Mycobacterium tuberculosis.
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Affiliation(s)
- H Mahdiuni
- Laboratory of Membrane Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, P.O. Box 1384-13145, Tehran, Iran
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Gueriri I, Bay S, Dubrac S, Cyncynatus C, Msadek T. The Pta-AckA pathway controlling acetyl phosphate levels and the phosphorylation state of the DegU orphan response regulator both play a role in regulating Listeria monocytogenes motility and chemotaxis. Mol Microbiol 2008; 70:1342-57. [PMID: 19019159 DOI: 10.1111/j.1365-2958.2008.06496.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DegU is considered to be an orphan response regulator in Listeria monocytogenes since the gene encoding the cognate histidine kinase DegS is absent from the genome. We have previously shown that DegU is involved in motility, chemotaxis and biofilm formation and contributes to L. monocytogenes virulence. Here, we have investigated the role of DegU phosphorylation in Listeria and shown that DegS of Bacillus subtilis can phosphorylate DegU of L. monocytogenes in vitro. We introduced the B. subtilis degS gene into L. monocytogenes, and showed that this leads to highly increased expression of motility and chemotaxis genes, in a DegU-dependent fashion. We inactivated the predicted phosphorylation site of DegU by replacing aspartate residue 55 with asparagine and showed that this modified protein (DegU(D55N)) is no longer phosphorylated by DegS in vitro. We show that although the unphosphorylated form of DegU retains much of its activity in vivo, expression of motility and chemotaxis genes is lowered in the degU(D55N) mutant. We also show that the small-molecular-weight metabolite acetyl phosphate is an efficient phosphodonor for DegU in vitro and our evidence suggests this is also true in vivo. Indeed, a L. monocytogenesDeltaptaDeltaackA mutant that can no longer synthesize acetyl phosphate was found to be strongly affected in chemotaxis and motility gene expression and biofilm formation. Our findings suggest that phosphorylation by acetyl phosphate could play an important role in modulating DegU activity in vivo, linking its phosphorylation state to the metabolic status of L. monocytogenes.
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Affiliation(s)
- Ibtissem Gueriri
- Biology of Gram-Positive Pathogens, Department of Microbiology, CNRS URA 2172, Paris, France
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Abstract
Two-component signal transduction systems enable bacteria to sense, respond, and adapt to a wide range of environments, stressors, and growth conditions. In the prototypical two-component system, a sensor histidine kinase catalyzes its autophosphorylation and then subsequently transfers the phosphoryl group to a response regulator, which can then effect changes in cellular physiology, often by regulating gene expression. The utility of these signaling systems is underscored by their prevalence throughout the bacterial kingdom and by the fact that many bacteria contain dozens, or sometimes hundreds, of these signaling proteins. The presence of so many highly related signaling proteins in individual cells creates both an opportunity and a challenge. Do cells take advantage of the similarity between signaling proteins to integrate signals or diversify responses, and thereby enhance their ability to process information? Conversely, how do cells prevent unwanted cross-talk and maintain the insulation of distinct pathways? Here we address both questions by reviewing the cellular and molecular mechanisms that dictate the specificity of two-component signaling pathways.
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Affiliation(s)
- Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Bibb LA, Kunkle CA, Schmitt MP. The ChrA-ChrS and HrrA-HrrS signal transduction systems are required for activation of the hmuO promoter and repression of the hemA promoter in Corynebacterium diphtheriae. Infect Immun 2007; 75:2421-31. [PMID: 17353293 PMCID: PMC1865786 DOI: 10.1128/iai.01821-06] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription of the Corynebacterium diphtheriae hmuO gene, which encodes a heme oxygenase involved in heme iron utilization, is activated in a heme- or hemoglobin-dependent manner in part by the two-component system ChrA-ChrS. Mutation of either the chrA or the chrS gene resulted in a marked reduction of hemoglobin-dependent activation at the hmuO promoter in C. diphtheriae; however, it was observed that significant levels of hemoglobin-dependent expression were maintained in the mutants, suggesting that an additional activator is involved in regulation. A BLAST search of the C. diphtheriae genome sequence revealed a second two-component system, encoded by DIP2268 and DIP2267, that shares similarity with ChrS and ChrA, respectively; we have designated these genes hrrS (DIP2268) and hrrA (DIP2267). Analysis of hmuO promoter expression demonstrated that hemoglobin-dependent activity was fully abolished in strains from which both the chrA-chrS and the hrrA-hrrS two-component systems were deleted. Similarly, deletion of the sensor kinase genes chrS and hrrS or the genes encoding both of the response regulators chrA and hrrA also eliminated hemoglobin-dependent activation at the hmuO promoter. We also show that the regulators ChrA-ChrS and HrrA-HrrS are involved in the hemoglobin-dependent repression of the promoter upstream of hemA, which encodes a heme biosynthesis enzyme. Evidence for cross talk between the ChrA-ChrS and HrrA-HrrS systems is presented. In conclusion, these findings demonstrate that the ChrA-ChrS and HrrA-HrrS regulatory systems are critical for full hemoglobin-dependent activation at the hmuO promoter and also suggest that these two-component systems are involved in the complex mechanism of the regulation of heme homeostasis in C. diphtheriae.
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Affiliation(s)
- Lori A Bibb
- Laboratory of Respiratory and Special Pathogens, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
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Yang HH, Morrow JB, Grasso D, Vinopal RT, Smets BF. Intestinal versus external growth conditions change the surficial properties in a collection of environmental Escherichia coli isolates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:6976-82. [PMID: 17154004 DOI: 10.1021/es061100t] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Predicting the fate of microorganisms in the environment is increasingly warranted, especially for pathogenic strains. A major habitat of Escherichia coli, which encompasses commensal as well as pathogenic strains, is the gastrointestinal tract with conditions very different from the environment it encounters after shedding from the host or during cultivation in the laboratory. We developed two relevant growth conditions representative of intestinal (host-associated) and external (postshedding) environments to investigate the surficial properties and behaviors of a diverse subset of E. coli feedlot isolates. Surficial properties may determine an isolate's physical fate. A pronounced increase in cell hydrophobicity and concomitant biofilm mass formation was observed for isolates grown under external conditions. Isolates that exhibited the highest surface hydrophobicity also formed visible suspended aggregates under external conditions. Other than hydrophobicity, flagella-mediated motility was determinant in affecting E. coli biofilm formation under external conditions, with all four nonmotile E. coli isolates characterized as thin-biofilm formers. The majority (88%) of Ag43+ (outer membrane protein, antigen 43) isolates formed thick biofilms, whereas the majority (75%) of Ag43- isolates formed thin biofilms. The tested E. coli O157:H7 strain behaved differently from the environmental E. coli isolates: it displayed a low electrostatic charge, a small decrease in hydrophobicity upon shifts to external conditions, and very little biofilm formation. On the other hand, the commonly used laboratory strain E. coli K-12 displayed low hydrophobicity both intestinally and externally, but it formed significant biofilm mass under external conditions. Clearly, various E. coli strains manifest significant variability in surficial behavior. This variability is further modulated by growth conditions. The interacting strain-inherent and cultivation-dependent effects on surficial behavior may have broad consequences for the fate and ecology of pathogenic and commensal E. coli strains.
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Affiliation(s)
- Hsiao-Hui Yang
- Microbiology Program and Environmental Engineering Program, University of Connecticut, Storrs, Connecticut 06269, USA
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Weber A, Kögl SA, Jung K. Time-dependent proteome alterations under osmotic stress during aerobic and anaerobic growth in Escherichia coli. J Bacteriol 2006; 188:7165-75. [PMID: 17015655 PMCID: PMC1636219 DOI: 10.1128/jb.00508-06] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli lives in the mammalian gastrointestinal tract anaerobically at high osmolarity as well as in the soil aerobically at varying osmolarities. Adaptation to these varying environmental conditions is crucial for growth and survival of E. coli. Two-dimensional protein gels were used to visualize global time-dependent changes (10 to 60 min) in the proteome of cells responding to osmotic stress (0.4 M NaCl or 0.7 M sorbitol) under aerobic or anaerobic conditions. The protein profiles revealed an induction of 12 proteins (Dps, HchA, HdhA, InfB, OsmC, OsmY, ProX, KatE, PspA, TalA, TktB, and TreF) under osmotic stress in an aerobic milieu. Eleven additional proteins (OtsB, YceI, YciE, YciF, YgaU, YjbJ, AcnA, MetL, PoxB, Ssb, and YhbO) were induced by osmotic stress imposed by NaCl. Most of the accumulated proteins were cross-protecting proteins (e.g., OsmY, OsmC, Dps, and KatE) which are regulated at the transcriptional level predominantly by RpoS and other regulators (e.g., integration host factor, OxyR, H-NS, LRP, and FIS). Comparative analysis of the proteome of E. coli grown under aerobic or anaerobic conditions under osmotic stress (NaCl) revealed an overlap of the up-regulated proteins of more than 50%. Ten proteins (PoxB, AcnA, TalA, TktB, KatE, PspA, Ssb, TreF, MetL, and YhbO) were detectable only under aerobic, high-osmolality conditions. Time-dependent alterations of the proteome were monitored, allowing classification of the up-regulated proteins into early, middle, and long-term phases of adaptation. Only a few proteins were found to be down-regulated upon osmotic stress.
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Affiliation(s)
- Arnim Weber
- Ludwig-Maximilians-Universität München, Department Biologie I, Bereich Mikrobiologie, Maria-Ward-Str. 1a, D-80638 München, Germany
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Leech AJ, Mattick JS. Effect of site-specific mutations in different phosphotransfer domains of the chemosensory protein ChpA on Pseudomonas aeruginosa motility. J Bacteriol 2006; 188:8479-86. [PMID: 17012390 PMCID: PMC1698234 DOI: 10.1128/jb.00157-06] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The virulence of Pseudomonas aeruginosa and other surface pathogens involves the coordinate expression of a wide range of virulence determinants, including type IV pili. These surface filaments are important for the colonization of host epithelial tissues and mediate bacterial attachment to, and translocation across, surfaces by a process known as twitching motility. This process is controlled in part by a complex signal transduction system whose central component, ChpA, possesses nine potential sites of phosphorylation, including six histidine-containing phosphotransfer (HPt) domains, one serine-containing phosphotransfer domain, one threonine-containing phosphotransfer domain, and one CheY-like receiver domain. Here, using site-directed mutagenesis, we show that normal twitching motility is entirely dependent on the CheY-like receiver domain and partially dependent on two of the HPt domains. Moreover, under different assay conditions, point mutations in several of the phosphotransfer domains of ChpA give rise to unusual "swarming" phenotypes, possibly reflecting more subtle perturbations in the control of P. aeruginosa motility that are not evident from the conventional twitching stab assay. Together, these results suggest that ChpA plays a central role in the complex regulation of type IV pilus-mediated motility in P. aeruginosa.
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Affiliation(s)
- Andrew J Leech
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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47
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Laskowski MA, Kazmierczak BI. Mutational analysis of RetS, an unusual sensor kinase-response regulator hybrid required for Pseudomonas aeruginosa virulence. Infect Immun 2006; 74:4462-73. [PMID: 16861632 PMCID: PMC1539586 DOI: 10.1128/iai.00575-06] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen capable of causing both acute and chronic infections in a wide range of hosts. Expression of the type III secretion system (T3SS) proteins is correlated with virulence in models of acute infection, while downregulation of the T3SS and upregulation of genes important for biofilm formation are observed during chronic infections. RetS, a hybrid sensor kinase-response regulator protein of P. aeruginosa, plays a key role in the reciprocal regulation of virulence factors required for acute versus chronic infection and is postulated to act in concert with two other sensor kinase-response regulator hybrids, GacS and LadS. This work examines the roles of the putative sensing and signal transduction domains of RetS in induction of the T3SS in vitro and in a murine model of acute pneumonia. We identify distinct signaling roles for the tandem receiver domains of RetS and present evidence suggesting that RetS may serve as a substrate for another sensor kinase. Phenotypes associated with RetS alleles lacking periplasmic and/or transmembrane domains further indicate that the periplasmic domain of RetS may transmit a signal that inhibits RetS activity during acute infections.
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Affiliation(s)
- Michelle A Laskowski
- Program in Microbiology, Yale University School of Medicine, 333 Cedar Street, P.O. Box 208022, New Haven, Connecticut 06520-8022, USA
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Begic S, Worobec EA. Regulation of Serratia marcescens ompF and ompC porin genes in response to osmotic stress, salicylate, temperature and pH. MICROBIOLOGY-SGM 2006; 152:485-491. [PMID: 16436436 DOI: 10.1099/mic.0.28428-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Serratia marcescens is a Gram-negative enterobacterium that has become an important opportunistic pathogen, largely due to its high degree of natural antibiotic resistance. One factor contributing to this natural antibiotic resistance is reduced outer membrane permeability, which is controlled in part by OmpC and OmpF porin proteins. OmpF expression is regulated by micF, an RNA transcript encoded upstream of the ompC gene, which hybridizes with the ompF transcript to inhibit its translation. Regulation of S. marcescens porin gene expression, as well as that of micF, was investigated using beta-galactosidase reporter gene fusions in response to 5, 8 and 10 % sucrose, 1, 5 and 8 mM salicylate, and different pH and temperature values. beta-Galactosidase activity assays revealed that a lower growth temperature (28 degrees C), a more basic pH (pH 8), and an absence of sucrose and salicylate induce the transcription of the ompF gene, whereas the induction of ompC is stimulated at a higher growth temperature (42 degrees C), acidic pH (pH 6), and maximum concentrations of sucrose (10 %) and salicylate (8 mM). In addition, when multiple conditions were tested, temperature had the predominant effect, followed by pH. In this study, it was found that the MicF regulatory mechanism does not play a role in the osmoregulation of the ompF and ompC genes, whereas MicF does repress OmpF expression in the presence of salicylate and high growth temperature, and under low pH conditions.
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Affiliation(s)
- Sanela Begic
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Elizabeth A Worobec
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
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Vemuri GN, Aristidou AA. Metabolic engineering in the -omics era: elucidating and modulating regulatory networks. Microbiol Mol Biol Rev 2006; 69:197-216. [PMID: 15944454 PMCID: PMC1197421 DOI: 10.1128/mmbr.69.2.197-216.2005] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The importance of regulatory control in metabolic processes is widely acknowledged, and several enquiries (both local and global) are being made in understanding regulation at various levels of the metabolic hierarchy. The wealth of biological information has enabled identifying the individual components (genes, proteins, and metabolites) of a biological system, and we are now in a position to understand the interactions between these components. Since phenotype is the net result of these interactions, it is immensely important to elucidate them not only for an integrated understanding of physiology, but also for practical applications of using biological systems as cell factories. We present some of the recent "-omics" approaches that have expanded our understanding of regulation at the gene, protein, and metabolite level, followed by analysis of the impact of this progress on the advancement of metabolic engineering. Although this review is by no means exhaustive, we attempt to convey our ideology that combining global information from various levels of metabolic hierarchy is absolutely essential in understanding and subsequently predicting the relationship between changes in gene expression and the resulting phenotype. The ultimate aim of this review is to provide metabolic engineers with an overview of recent advances in complementary aspects of regulation at the gene, protein, and metabolite level and those involved in fundamental research with potential hurdles in the path to implementing their discoveries in practical applications.
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Affiliation(s)
- Goutham N Vemuri
- Center for Molecular BioEngineering, Drifmier Engineering Center, University of Georgia, Athens, 30605, USA
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50
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Bekker M, Teixeira De Mattos MJ, Hellingwerf KJ. The role of two-component regulation systems in the physiology of the bacterial cell. Sci Prog 2006; 89:213-42. [PMID: 17338439 PMCID: PMC10368358 DOI: 10.3184/003685006783238308] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two-component regulation systems (TCRSs) are the dominant type of signal transduction system in prokaryotes that are used to inform the cellular trancriptional machinery (and additional targets for regulation, like the motility apparatus) about actual changes in the extracellular physicochemical conditions. We now review their molecular structure and enzymatic characteristics, their mutual interactions and its implications, and their role in cellular physiology. Specific emphasis is placed on the ArcB/A system, a representative of the phosphorelay type of TCRS, and a key player in the adjustment of the cellular make-up of enterobacteria in response to alterations in the oxygen availability. Also some applied aspects of the TCRSs are discussed, i.e. their role as a target to develop new anti-bacterials and their application in biotechnology (or: 'synthetic biology').
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Affiliation(s)
| | | | - Klaas J. Hellingwerf
- Laboratory for Microbiology, Swammerdam Institute for Life Sciences, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
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