1
|
Nwokocha GC, Ghosh A, Grove A. Regulation of bacterial virulence genes by PecS family transcription factors. J Bacteriol 2024:e0030224. [PMID: 39287432 DOI: 10.1128/jb.00302-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2024] Open
Abstract
Bacterial plant pathogens adjust their gene expression programs in response to environmental signals and host-derived compounds. This ensures that virulence genes or genes encoding proteins, which promote bacterial fitness in a host environment, are expressed only when needed. Such regulation is in the purview of transcription factors, many of which belong to the ubiquitous multiple antibiotic resistance regulator (MarR) protein family. PecS proteins constitute a subset of this large protein family. PecS has likely been distributed by horizontal gene transfer, along with the divergently encoded efflux pump PecM, suggesting its integration into existing gene regulatory networks. Here, we discuss the roles of PecS in the regulation of genes associated with virulence and fitness of bacterial plant pathogens. A comparison of phenotypes and differential gene expression associated with the disruption of pecS shows that functional consequences of PecS integration into existing transcriptional networks are highly variable, resulting in distinct PecS regulons. Although PecS universally binds to the pecS-pecM intergenic region to repress the expression of both genes, binding modes differ. A particularly relaxed sequence preference appears to apply for Dickeya dadantii PecS, perhaps to optimize its integration as a global regulator and regulate genes ancestral to the acquisition of pecS-pecM. Even inducing ligands for PecS are not universally conserved. It appears that PecS function has been optimized to match the unique regulatory needs of individual bacterial species and that its roles must be appreciated in the context of the regulatory networks into which it was recruited.
Collapse
Affiliation(s)
| | - Arpita Ghosh
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Anne Grove
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| |
Collapse
|
2
|
Clara L, David C, Laila S, Virginie R, Marie-Joelle V. Comparative Proteomic Analysis of Transcriptional and Regulatory Proteins Abundances in S. lividans and S. coelicolor Suggests a Link between Various Stresses and Antibiotic Production. Int J Mol Sci 2022; 23:ijms232314792. [PMID: 36499130 PMCID: PMC9739823 DOI: 10.3390/ijms232314792] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/29/2022] Open
Abstract
Streptomyces coelicolor and Streptomyces lividans constitute model strains to study the regulation of antibiotics biosynthesis in Streptomyces species since these closely related strains possess the same pathways directing the biosynthesis of various antibiotics but only S. coelicolor produces them. To get a better understanding of the origin of the contrasted abilities of these strains to produce bioactive specialized metabolites, these strains were grown in conditions of phosphate limitation or proficiency and a comparative analysis of their transcriptional/regulatory proteins was carried out. The abundance of the vast majority of the 355 proteins detected greatly differed between these two strains and responded differently to phosphate availability. This study confirmed, consistently with previous studies, that S. coelicolor suffers from nitrogen stress. This stress likely triggers the degradation of the nitrogen-rich peptidoglycan cell wall in order to recycle nitrogen present in its constituents, resulting in cell wall stress. When an altered cell wall is unable to fulfill its osmo-protective function, the bacteria also suffer from osmotic stress. This study thus revealed that these three stresses are intimately linked in S. coelicolor. The aggravation of these stresses leading to an increase of antibiotic biosynthesis, the connection between these stresses, and antibiotic production are discussed.
Collapse
Affiliation(s)
- Lejeune Clara
- Institute for Integrative Biology of the Cell (I2BC), Department of Microbiology, Group “Energetic Metabolism of Streptomyces”, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Cornu David
- Institute for Integrative Biology of the Cell (I2BC), Department of Microbiology, Group “Energetic Metabolism of Streptomyces”, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Sago Laila
- Institute for Integrative Biology of the Cell (I2BC), Department of Microbiology, Group “Energetic Metabolism of Streptomyces”, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Redeker Virginie
- Institute for Integrative Biology of the Cell (I2BC), Department of Microbiology, Group “Energetic Metabolism of Streptomyces”, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
- Laboratory of Neurodegenerative Diseases, Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) and Centre National de la Recherche Scientifique (CNRS), Molecular Imaging Center (MIRCen), Institut François Jacob, Université Paris-Saclay, 92260 Fontenay-aux-Roses, France
| | - Virolle Marie-Joelle
- Institute for Integrative Biology of the Cell (I2BC), Department of Microbiology, Group “Energetic Metabolism of Streptomyces”, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
- Correspondence:
| |
Collapse
|
3
|
A Major Facilitator Superfamily (MFS) Efflux Pump, SCO4121, from Streptomyces coelicolor with Roles in Multidrug Resistance and Oxidative Stress Tolerance and Its Regulation by a MarR Regulator. Appl Environ Microbiol 2021; 87:AEM.02238-20. [PMID: 33483304 DOI: 10.1128/aem.02238-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 01/12/2021] [Indexed: 12/12/2022] Open
Abstract
Overexpression of efflux pumps is one of the major determinants of resistance in bacteria. Streptomyces species harbor a large array of efflux pumps that are transcriptionally silenced under laboratory conditions. However, their dissemination results in multidrug resistance in different clinical pathogens. In this study, we have identified an efflux pump from Streptomyces coelicolor, SCO4121, belonging to the major facilitator superfamily (MFS) family of transporters and characterized its role in antibiotic resistance. SCO4121 provided resistance to multiple dissimilar drugs upon overexpression in both native and heterologous hosts. Further, deletion of SCO4121 resulted in increased sensitivity toward ciprofloxacin and chloramphenicol, suggesting the pump to be a major transporter of these substrates. Apart from providing multidrug resistance, SCO4121 imparted increased tolerance against the strong oxidant HOCl. In wild-type Streptomyces coelicolor cells, these drugs were found to transcriptionally regulate the pump in a concentration-dependent manner. Additionally, we identified SCO4122, a MarR regulator that positively regulates SCO4121 in response to various drugs and the oxidant HOCl. Thus, through these studies we present the multiple roles of SCO4121 in S. coelicolor and highlight the intricate mechanisms via which it is regulated in response to antibiotics and oxidative stress.IMPORTANCE One of the key mechanisms of drug resistance in bacteria is overexpression of efflux pumps. Streptomyces species are a reservoir of a large number of efflux pumps, potentially to provide resistance to both endogenous and nonendogenous antibiotics. While many of these pumps are not expressed under standard laboratory conditions, they result in resistance to multiple drugs when spread to other bacterial pathogens through horizontal gene transfer. In this study, we have identified a widely conserved efflux pump SCO4121 from Streptomyces coelicolor with roles in both multidrug resistance and oxidative stress tolerance. We also report the presence of an adjacent MarR regulator, SCO4122, which positively regulates SCO4121 in the presence of diverse substrates in a redox-responsive manner. This study highlights that soil bacteria such as Streptomyces can reveal novel mechanisms of antibiotic resistance that may potentially emerge in clinically important bacteria.
Collapse
|
4
|
Deochand DK, Pande A, Meariman JK, Grove A. Redox Sensing by PecS from the Plant Pathogen Pectobacterium atrosepticum and Its Effect on Gene Expression and the Conformation of PecS-Bound Promoter DNA. Biochemistry 2019; 58:2564-2575. [PMID: 31046241 DOI: 10.1021/acs.biochem.9b00288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The plant pathogen Pectobacterium atrosepticum encounters a stressful environment when it colonizes the plant apoplast. Chief among the stressors are the reactive oxygen species (ROS) that are produced by the host as a first line of defense. Bacterial transcription factors in turn use these signals as cues to upregulate expression of virulence-associated genes. We have previously shown that the transcription factor PecS from P. atrosepticum binds the promoters that drive expression of pecS and pecM, which encodes an efflux pump, to repress gene expression. We show here that addition of oxidant relieves repression in vivo and in vitro. While reduced PecS distorts promoter DNA on binding, oxidized PecS does not, as evidenced by DNaseI footprinting. PecS oxidation is reversible, as shown by an oxidant-dependent quenching of the intrinsic tryptophan fluorescence that is completely reversed upon addition of a reducing agent. Cysteine 45 positioned at the PecS dimer interface is the redox sensor. Reduced PecS-C45A causes less DNA distortion on binding compared to wild-type PecS; addition of an oxidant has no effect on binding, and PecS-C45A cannot repress gene expression. Our data suggest that reduced PecS distorts its cognate DNA on binding, perhaps inducing a conformation in which promoter elements are suboptimally aligned for RNA polymerase binding, resulting in transcriptional repression. In contrast, oxidized PecS binds promoter DNA such that RNA polymerase may successfully compete with PecS for binding, allowing gene expression. This mode of regulation would facilitate induction of the PecS regulon when the bacteria encounter host-derived ROS in the plant apoplast.
Collapse
Affiliation(s)
- Dinesh K Deochand
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Anuja Pande
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Jacob K Meariman
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Anne Grove
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| |
Collapse
|
5
|
Gong Z, Li H, Cai Y, Stojkoska A, Xie J. Biology of MarR family transcription factors and implications for targets of antibiotics against tuberculosis. J Cell Physiol 2019; 234:19237-19248. [PMID: 31012115 DOI: 10.1002/jcp.28720] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/03/2019] [Accepted: 04/10/2019] [Indexed: 12/12/2022]
Abstract
The emergence of multidrug resistant (MDR) Mycobacterium tuberculosis strains and increased incidence of HIV coinfection fueled the difficulty in controlling tuberculosis (TB). MarR (multiple antibiotic resistance regulator) family transcription factors can regulate marRAB operon and are involved in resistance to multiple environmental stresses. We have summarized the structure, function, distribution, and regulation of the MarR family proteins, as well as their implications for novel targets for antibiotics, especially for tuberculosis.
Collapse
Affiliation(s)
- Zhen Gong
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Hui Li
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Yuhua Cai
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Andrea Stojkoska
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Jianping Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| |
Collapse
|
6
|
Abstract
The genus Vibrio includes serious human pathogens, and mollusks are a significant reservoir for species such as V. vulnificus. Vibrio species encode PecS, a member of the multiple antibiotic resistance regulator (MarR) family of transcription factors; pecS is divergently oriented to pecM, which encodes an efflux pump. We report here that Vibrio species feature frequent duplications of pecS-pecM genes, suggesting evolutionary pressures to respond to distinct environmental situations. The single V. vulnificus PecS binds two sites within the pecS-pecM intergenic region with Kd = 0.3 ± 0.1 nM, a binding that is attenuated by the ligands xanthine and urate, except when promoter DNA is saturated with PecS. A unique target is found in the intergenic region between genes encoding the nitric oxide sensing transcription factor, NsrR, and nod; the nod-encoded nitric oxide dioxygenase is important for preventing nitric oxide stress. Reporter gene assays show that PecS-mediated repression of gene expression can be relieved in presence of ligand. Since xanthine and urate are produced as part of the oxidative burst during host defenses and under molluscan hypoxia, we propose that these intermediates in the host purine degradation pathway function to promote bacterial survival during hypoxia and oxidative stress.
Collapse
|
7
|
Guo J, Zhang X, Lu X, Liu W, Chen Z, Li J, Deng L, Wen Y. SAV4189, a MarR-Family Regulator in Streptomyces avermitilis, Activates Avermectin Biosynthesis. Front Microbiol 2018; 9:1358. [PMID: 30013524 PMCID: PMC6036246 DOI: 10.3389/fmicb.2018.01358] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/05/2018] [Indexed: 12/15/2022] Open
Abstract
The bacterial species Streptomyces avermitilis is an important industrial producer of avermectins, which are widely utilized as effective anthelmintic and insecticidal drugs. We used gene deletion, complementation, and overexpression experiments to identify SAV4189, a MarR-family transcriptional regulator (MFR) in this species, as an activator of avermectin biosynthesis. SAV4189 indirectly stimulated avermectin production by altering expression of cluster-situated activator gene aveR, and directly repressed the transcription of its own gene (sav_4189) and adjacent cotranscribed gene sav_4190 (which encodes an unknown transmembrane efflux protein). A consensus 13-bp palindromic sequence, 5'-TTGCCYKHRSCAA-3' (Y = T/C; K = T/G; H = A/C/T; R = A/G; S = C/G), was found within the SAV4189-binding sites of its own promoter region, and shown to be essential for binding. The SAV4189 regulon was thus predicted based on bioinformatic analysis. Night new identified SAV4189 targets are involved in transcriptional regulation, primary metabolism, secondary metabolism, and stress response, reflecting a pleiotropic role of SAV4189. sav_4190, the important target gene of SAV4189, exerted a negative effect on avermectin production. sav_4189 overexpression and sav_4190 deletion in S. avermitilis wild-type and industrial strains significantly increased avermectin production. SAV4189 homologs are widespread in other Streptomyces species. sav_4189 overexpression in the model species S. coelicolor also enhanced antibiotic production. The strategy of increasing yield of important antibiotics by engineering of SAV4189 homologs and target gene may potentially be extended to other industrial Streptomyces species. In addition, SAV4189 bound and responded to exogenous antibiotics hygromycin B and thiostrepton to modulate its DNA-binding activity and transcription of target genes. SAV4189 is the first reported exogenous antibiotic receptor among Streptomyces MFRs.
Collapse
Affiliation(s)
- Jia Guo
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
- Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, China
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Xuan Zhang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiaorui Lu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Wenshuai Liu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Zhi Chen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jilun Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Linhong Deng
- Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, China
| | - Ying Wen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| |
Collapse
|
8
|
Sivapragasam S, Deochand DK, Meariman JK, Grove A. The Stringent Response Induced by Phosphate Limitation Promotes Purine Salvage in Agrobacterium fabrum. Biochemistry 2017; 56:5831-5843. [DOI: 10.1021/acs.biochem.7b00844] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Smitha Sivapragasam
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Dinesh K. Deochand
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Jacob K. Meariman
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Anne Grove
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| |
Collapse
|
9
|
Deochand DK, Grove A. MarR family transcription factors: dynamic variations on a common scaffold. Crit Rev Biochem Mol Biol 2017; 52:595-613. [PMID: 28670937 DOI: 10.1080/10409238.2017.1344612] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Members of the multiple antibiotic resistance regulator (MarR) family of transcription factors are critical for bacterial cells to respond to chemical signals and to convert such signals into changes in gene activity. Obligate dimers belonging to the winged helix-turn-helix protein family, they are critical for regulation of a variety of functions, including degradation of organic compounds and control of virulence gene expression. The conventional regulatory paradigm is based on a genomic locus in which the gene encoding the MarR protein is divergently oriented from a gene under its control; MarR binding to the intergenic region controls expression of both genes by changing the interaction of RNA polymerase with gene promoters. MarR protein oxidation or binding of a small molecule ligand adversely affects DNA binding, resulting in altered expression of the divergent genes. The generality of this simple paradigm, including the regulation of Escherichia coli MarR by direct binding of antibiotics, has been challenged by reports published in recent years. In addition, structural and biochemical analyses of ligand binding to numerous MarR homologs are converging to identify a shared ligand-binding "hot-spot". This review highlights recent research advances that point to shared features, yet at the same time highlights the remarkable flexibility with which members of this protein family implement responses to inducing signals. A more comprehensive understanding of protein function will pave the way towards the development of both antibacterial agents and biosensors that are based on MarR family proteins.
Collapse
Affiliation(s)
- Dinesh K Deochand
- a Department of Biological Sciences , Louisiana State University , Baton Rouge , LA , USA
| | - Anne Grove
- a Department of Biological Sciences , Louisiana State University , Baton Rouge , LA , USA
| |
Collapse
|
10
|
Deochand DK, Meariman JK, Grove A. pH-Dependent DNA Distortion and Repression of Gene Expression by Pectobacterium atrosepticum PecS. ACS Chem Biol 2016; 11:2049-56. [PMID: 27213700 DOI: 10.1021/acschembio.6b00168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Transcriptional activity is exquisitely sensitive to changes in promoter DNA topology. Transcription factors may therefore control gene activity by modulating the relative positioning of -10 and -35 promoter elements. The plant pathogen Pectobacterium atrosepticum, which causes soft rot in potatoes, must alter gene expression patterns to ensure growth in planta. In the related soft-rot enterobacterium Dickeya dadantii, PecS functions as a master regulator of virulence gene expression. Here, we report that P. atrosepticum PecS controls gene activity by altering promoter DNA topology in response to pH. While PecS binds the pecS promoter with high affinity regardless of pH, it induces significant DNA distortion only at neutral pH, the pH at which the pecS promoter is repressed in vivo. At pH ∼8, DNA distortions are attenuated, and PecS no longer represses the pecS promoter. A specific histidine (H142) located in a crevice between the dimerization- and DNA-binding regions is required for pH-dependent changes in DNA distortion and repression of gene activity, and mutation of this histidine renders the mutant protein incapable of repressing the pecS promoter. We propose that protonated PecS induces a DNA conformation at neutral pH in which -10 and -35 promoter elements are suboptimally positioned for RNA polymerase binding; on deprotonation of PecS, binding is no longer associated with significant changes in DNA conformation, allowing gene expression. We suggest that this mode of gene regulation leads to differential expression of the PecS regulon in response to alkalinization of the plant apoplast.
Collapse
Affiliation(s)
- Dinesh K. Deochand
- Department
of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Jacob K. Meariman
- Department
of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Anne Grove
- Department
of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| |
Collapse
|
11
|
Otani H, Stogios PJ, Xu X, Nocek B, Li SN, Savchenko A, Eltis LD. The activity of CouR, a MarR family transcriptional regulator, is modulated through a novel molecular mechanism. Nucleic Acids Res 2015; 44:595-607. [PMID: 26400178 PMCID: PMC4737184 DOI: 10.1093/nar/gkv955] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/11/2015] [Indexed: 12/21/2022] Open
Abstract
CouR, a MarR-type transcriptional repressor, regulates the cou genes, encoding p-hydroxycinnamate catabolism in the soil bacterium Rhodococcus jostii RHA1. The CouR dimer bound two molecules of the catabolite p-coumaroyl-CoA (Kd = 11 ± 1 μM). The presence of p-coumaroyl-CoA, but neither p-coumarate nor CoASH, abrogated CouR's binding to its operator DNA in vitro. The crystal structures of ligand-free CouR and its p-coumaroyl-CoA-bound form showed no significant conformational differences, in contrast to other MarR regulators. The CouR-p-coumaroyl-CoA structure revealed two ligand molecules bound to the CouR dimer with their phenolic moieties occupying equivalent hydrophobic pockets in each protomer and their CoA moieties adopting non-equivalent positions to mask the regulator's predicted DNA-binding surface. More specifically, the CoA phosphates formed salt bridges with predicted DNA-binding residues Arg36 and Arg38, changing the overall charge of the DNA-binding surface. The substitution of either arginine with alanine completely abrogated the ability of CouR to bind DNA. By contrast, the R36A/R38A double variant retained a relatively high affinity for p-coumaroyl-CoA (Kd = 89 ± 6 μM). Together, our data point to a novel mechanism of action in which the ligand abrogates the repressor's ability to bind DNA by steric occlusion of key DNA-binding residues and charge repulsion of the DNA backbone.
Collapse
Affiliation(s)
- Hiroshi Otani
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Xiaohui Xu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Boguslaw Nocek
- Structural Biology Center, Biosciences Division, Argonne National Laboratory and the Midwest Center for Structural Genomics, Lemont, IL 60439, USA
| | - Shu-Nan Li
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Lindsay D Eltis
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| |
Collapse
|
12
|
Wang ZC, Liu CJ, Huang YJ, Wang YS, Peng HL. PecS regulates the urate-responsive expression of type 1 fimbriae in Klebsiella pneumoniae CG43. MICROBIOLOGY-SGM 2015; 161:2395-409. [PMID: 26385366 DOI: 10.1099/mic.0.000185] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In the Klebsiella pneumoniae CG43 genome, the divergently transcribed genes coding for PecS, the MarR-type transcription factor, and PecM, the drug metabolite transporter, are located between the type 1 and type 3 fimbrial gene clusters. The intergenic sequence pecO between pecS and pecM contains three putative PecS binding sites and a CpxR box. Electrophoretic mobility shift assay revealed that the recombinant PecS and CpxR could specifically bind to the pecO sequence, and the specific interaction of PecS and pecO could be attenuated by urate. The expression of pecS and pecM was negatively regulated by CpxAR and PecS, and was inducible by exogenous urate in the absence of cpxAR. Compared with CG43S3ΔcpxAR, the derived mutants CG43S3ΔcpxARΔpecS and CG43S3ΔcpxARΔpecSΔpecM exerted similar levels of sensitivity to H2O2 or paraquat, but higher levels of mannose-sensitive yeast agglutination activity and FimA production. The promoter activity and transcript levels of fimA in CG43S3ΔcpxAR were also increased by deleting pecS. However, no binding activity between PecS and the fimA promoter could be observed. Nevertheless, PecS deletion could reduce the expression of the global regulator HNS and release the negative effect of HNS on FimA expression. In CG43S3ΔcpxAR, the expression of FimA as well as PecS was inducible by urate, whilst urate-induced FimA expression was inhibited by the deletion of pecS. Taken together, we propose that K. pneumoniae PecS indirectly and negatively regulates the expression of type 1 fimbriae, and the regulation is urate-inducible in the absence of CpxAR.
Collapse
Affiliation(s)
- Zhe-Chong Wang
- 1 Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, ROC
| | - Chia-Jui Liu
- 1 Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, ROC
| | - Ying-Jung Huang
- 2 Division of Hematology-Oncology, Chang Gung Memorial Hospital, Tao Yuan, ROC
| | - Yu-Seng Wang
- 1 Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, ROC
| | - Hwei-Ling Peng
- 1 Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, ROC
| |
Collapse
|
13
|
Romero-Rodríguez A, Robledo-Casados I, Sánchez S. An overview on transcriptional regulators in Streptomyces. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1017-39. [PMID: 26093238 DOI: 10.1016/j.bbagrm.2015.06.007] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 12/19/2022]
Abstract
Streptomyces are Gram-positive microorganisms able to adapt and respond to different environmental conditions. It is the largest genus of Actinobacteria comprising over 900 species. During their lifetime, these microorganisms are able to differentiate, produce aerial mycelia and secondary metabolites. All of these processes are controlled by subtle and precise regulatory systems. Regulation at the transcriptional initiation level is probably the most common for metabolic adaptation in bacteria. In this mechanism, the major players are proteins named transcription factors (TFs), capable of binding DNA in order to repress or activate the transcription of specific genes. Some of the TFs exert their action just like activators or repressors, whereas others can function in both manners, depending on the target promoter. Generally, TFs achieve their effects by using one- or two-component systems, linking a specific type of environmental stimulus to a transcriptional response. After DNA sequencing, many streptomycetes have been found to have chromosomes ranging between 6 and 12Mb in size, with high GC content (around 70%). They encode for approximately 7000 to 10,000 genes, 50 to 100 pseudogenes and a large set (around 12% of the total chromosome) of regulatory genes, organized in networks, controlling gene expression in these bacteria. Among the sequenced streptomycetes reported up to now, the number of transcription factors ranges from 471 to 1101. Among these, 315 to 691 correspond to transcriptional regulators and 31 to 76 are sigma factors. The aim of this work is to give a state of the art overview on transcription factors in the genus Streptomyces.
Collapse
Affiliation(s)
- Alba Romero-Rodríguez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico
| | - Ivonne Robledo-Casados
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico
| | - Sergio Sánchez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico.
| |
Collapse
|
14
|
A MarR Family Transcriptional Regulator, DptR3, Activates Daptomycin Biosynthesis and Morphological Differentiation in Streptomyces roseosporus. Appl Environ Microbiol 2015; 81:3753-65. [PMID: 25819953 DOI: 10.1128/aem.00057-15] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/19/2015] [Indexed: 11/20/2022] Open
Abstract
Daptomycin produced by Streptomyces roseosporus is an important lipopeptide antibiotic used to treat human infections caused by Gram-positive pathogenic bacteria, including drug-resistant strains. The genetic basis for regulatory mechanisms of daptomycin production is poorly known. Here, we characterized the dptR3 gene, which encodes a MarR family transcriptional regulator located adjacent to the known daptomycin biosynthetic (dpt) genes. Deletion of dptR3 reduced daptomycin production significantly and delayed aerial mycelium formation and sporulation on solid media. Dissection of the mechanism underlying the function of DptR3 in daptomycin production revealed that it stimulates daptomycin production indirectly by altering the transcription of dpt structural genes. DptR3 directly activated the transcription of its own gene, dptR3, but repressed the transcription of the adjacent, divergent gene orf16 (which encodes a putative ABC transporter ATP-binding protein). A 66-nucleotide DptR3-binding site in the intergenic region of dptR3-orf16 was determined by DNase I footprinting, and the palindromic sequence TCATTGTTACCTATGCTCACAATGA (underlining indicates inverted repeats) in the protected region was found to be essential for DptR3 binding. orf16, the major target gene of DptR3, exerted a positive effect on daptomycin biosynthesis. Our findings indicate that DptR3 functions as a global regulator that positively controls daptomycin production and morphological development in S. roseosporus.
Collapse
|
15
|
Shu HY, Lin LC, Lin TK, Chen HP, Yang HH, Peng KC, Lin GH. Transcriptional regulation of the iac locus from Acinetobacter baumannii by the phytohormone indole-3-acetic acid. Antonie van Leeuwenhoek 2015; 107:1237-47. [PMID: 25726082 DOI: 10.1007/s10482-015-0417-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 02/24/2015] [Indexed: 11/25/2022]
Abstract
The iac locus is involved in indole-3-acetic acid (IAA) catabolism in Acinetobacter baumannii. Nine structural genes of iac are transcribed in the same direction, whereas iacR, which encodes a MarR-type transcriptional regulator, is transcribed in the opposite direction. The IacA protein, which is encoded by the second structural gene of the iac locus, is expressed in an IAA-dependent manner. Here, we characterized gene expression from this locus in wild type A. baumannii and in an iacR mutant; this revealed that the iacH promoter is negatively regulated by IacR. The transcriptional site of iacH was determined by using 5' rapid amplification of cDNA ends; one IacR-binding site was identified between positions -35 and +28 of the iacH promoter. Sequence analysis and an electrophoretic mobility shift assay indicated that recombinant IacR binds specifically to a sequence with dyad symmetry in the iacR-iacH overlapping promoters in the absence of IAA. In addition, a two-plasmid expression system in Escherichia coli showed that IAA probably serves as a ligand that binds to IacR and releases it from the iacH promoter, thereby allowing RNA polymerase to transcribe iac. Thus, iac is expressed in order to promote IAA degradation, whereas free IacR is required for iac repression. We conclude that IacR serves as a key regulator of IAA degradation in A. baumannii in the rhizosphere. These results provide new insights into the possible role of A. baumannii in the environment.
Collapse
Affiliation(s)
- Hung-Yu Shu
- Department of Bioscience Technology, Chang Jung Christian University, Tainan, 711, Taiwan
| | | | | | | | | | | | | |
Collapse
|
16
|
Gupta A, Grove A. Ligand-binding pocket bridges DNA-binding and dimerization domains of the urate-responsive MarR homologue MftR from Burkholderia thailandensis. Biochemistry 2014; 53:4368-80. [PMID: 24955985 PMCID: PMC4100783 DOI: 10.1021/bi500219t] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
![]()
Members of the multiple antibiotic
resistance regulator (MarR)
family often regulate gene activity by responding to a specific ligand.
In the absence of ligand, most MarR proteins function as repressors,
while ligand binding causes attenuated DNA binding and therefore increased
gene expression. Previously, we have shown that urate is a ligand
for MftR (major facilitator transport regulator), which is encoded
by the soil bacterium Burkholderia thailandensis.
We show here that both mftR and the divergently oriented
gene mftP encoding a major facilitator transport
protein are upregulated in the presence of urate. MftR binds two cognate
sites in the mftR-mftP intergenic region with equivalent
affinity and sensitivity to urate. Mutagenesis of four conserved residues
previously reported to be involved in urate binding to Deinococcus
radiodurans HucR and Rhizobium radiobacter PecS significantly reduced protein stability and DNA binding affinity
but not ligand binding. These data suggest that residues equivalent
to those implicated in ligand binding to HucR and PecS serve structural
roles and that MftR relies on distinct residues for ligand binding.
MftR exhibits a two-step melting transition suggesting independent
unfolding of the dimerization and DNA-binding regions; urate binding
or mutations in the predicted ligand-binding sites result in one-step
unfolding transitions. We suggest that MftR binds the ligand in a
cleft between the DNA-binding lobes and the dimer interface but that
the mechanism of ligand-mediated attenuation of DNA binding differs
from that proposed for other urate-responsive MarR homologues. Since
DNA binding by MftR is attenuated at 37 °C, our data also suggest
that MftR responds to both ligand and a thermal upshift by attenuated
DNA binding and upregulation of the genes under its control.
Collapse
Affiliation(s)
- Ashish Gupta
- Department of Biological Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | | |
Collapse
|