1
|
Jian P, Liu J, Li L, Song Q, Zhang D, Zhang S, Chai C, Zhao H, Zhao G, Zhu H, Qiao J. AcrR1, a novel TetR/AcrR family repressor, mediates acid and antibiotic resistance and nisin biosynthesis in Lactococcus lactis F44. J Dairy Sci 2024:S0022-0302(24)00806-3. [PMID: 38762103 DOI: 10.3168/jds.2024-24754] [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: 02/02/2024] [Accepted: 03/31/2024] [Indexed: 05/20/2024]
Abstract
Lactococcus lactis, widely used in the manufacture of dairy products, encounters various environmental stresses both in natural habitats and during industrial processes. It has evolved intricate machinery of stress sensing and defense to survive harsh stress conditions. Here, we identified a novel TetR/AcrR family transcription regulator, designated AcrR1, to be a repressor for acid and antibiotic tolerance that was derepressed in the presence of vancomycin or under acid stress. The survival rates of acrR1 deletion strain ΔAcrR1 under acid and vancomycin stresses were about 28.7-fold (pH 3.0, HCl), 8.57-fold (pH 4.0, lactic acid) and 2.73-fold (300 ng/mL vancomycin) as that of original strain F44. We also demonstrated that ΔAcrR1 was better able to maintain intracellular pH homeostasis and had a lower affinity to vancomycin. No evident effects of AcrR1 deletion on the growth and morphology of strain F44 were observed. Subsequently, we characterized that the transcription level of genes associated with amino acids biosynthesis, carbohydrate transport and metabolism, multiple drug resistance and DNA repair proteins significantly upregulated in ΔAcrR1 using transcriptome analysis and quantitative reverse transcription-PCR (qRT-PCR) assays. Additionally, AcrR1 could repress the transcription of nisin post-translational modification gene, nisC, leading to a 16.3% increase in nisin yield after AcrR1 deletion. Our results not only refined the knowledge of the regulatory mechanism of TetR/AcrR family regulator in L. lactis, but presented a potential strategy to enhance industrial production of nisin.
Collapse
Affiliation(s)
- Pingqiu Jian
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Jiaheng Liu
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China.
| | - Li Li
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Qianqian Song
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Di Zhang
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Shenyi Zhang
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Chaofan Chai
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Hui Zhao
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Guangrong Zhao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Hongji Zhu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Jianjun Qiao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| |
Collapse
|
2
|
Zhu Y, Luo B, Mou X, Song Y, Zhou Y, Luo Y, Sun B, Luo Y, Tang H, Su Z, Bao R. Pseudomonas aeruginosa regulator PvrA binds simultaneously to multiple pseudo-palindromic sites for efficient transcription activation. SCIENCE CHINA. LIFE SCIENCES 2024; 67:900-912. [PMID: 37938507 DOI: 10.1007/s11427-022-2363-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 05/10/2023] [Indexed: 11/09/2023]
Abstract
Tetracycline repressor (TetR) family regulators (TFRs) are the largest group of DNA-binding transcription factors and are widely distributed in bacteria and archaea. TFRs play vital roles in controlling the expression of various genes and regulating diverse physiological processes. Recently, a TFR protein Pseudomonas virulence regulator A (PvrA), was identified from Pseudomonas aeruginosa as the transcriptional activator of genes involved in fatty acid utilization and bacterial virulence. Here, we show that PvrA can simultaneously bind to multiple pseudo-palindromic sites and upregulate the expression levels of target genes. Cryo-electron microscopy (cryo-EM) analysis indicates the simultaneous DNA recognition mechanism of PvrA and suggests that the bound DNA fragments consist of a distorted B-DNA double helix. The crystal structure and functional analysis of PvrA reveal a hinge region that secures the correct domain motion for recognition of the promiscuous promoter. Additionally, our results showed that mutations disrupting the regulatory hinge region have differential effects on biofilm formation and pyocyanin biosynthesis, resulting in attenuated bacterial virulence. Collectively, these findings will improve the understanding of the relationship between the structure and function of the TetR family and provide new insights into the mechanism of regulation of P. aeruginosa virulence.
Collapse
Affiliation(s)
- Yibo Zhu
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
- Accurate Biotechnology (Hunan) Co., Ltd, Changsha, 410006, China
| | - Bingnan Luo
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xingyu Mou
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yingjie Song
- College of Life Science, Sichuan Normal University, Chengdu, 610101, China
| | - Yonghong Zhou
- Key Laboratory of Biodiversity and Environment on the Qinghai-Tibetan Plateau, Ministry of Education, School of Ecology and Environment, Tibet University, Lhasa, 850000, China
| | - Yongbo Luo
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Bo Sun
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Youfu Luo
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Hong Tang
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Zhaoming Su
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
- Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Rui Bao
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
| |
Collapse
|
3
|
Kosiorek K, Koryszewska-Bagińska A, Skoneczny M, Aleksandrzak-Piekarczyk T. Control of Bacterial Phenotype and Chromosomal Gene Expression by Single Plasmids of Lactococcus lactis IL594. Int J Mol Sci 2023; 24:9877. [PMID: 37373024 DOI: 10.3390/ijms24129877] [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: 04/18/2023] [Revised: 06/04/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Plasmid-free Lactococcus lactis IL1403 is one of the best-characterized representatives of lactic acid bacteria (LAB), intensively used in broad microbiology worldwide. Its parent strain, L. lactis IL594, contains seven plasmids (pIL1-pIL7) with resolved DNA sequences and an indicated role for overall plasmid load in enhancing host-adaptive potential. To determine how individual plasmids manipulate the expression of phenotypes and chromosomal genes, we conducted global comparative phenotypic analyses combined with transcriptomic studies in plasmid-free L. lactis IL1403, multiplasmid L. lactis IL594, and its single-plasmid derivatives. The presence of pIL2, pIL4, and pIL5 led to the most pronounced phenotypic differences in the metabolism of several carbon sources, including some β-glycosides and organic acids. The pIL5 plasmid also contributed to increased tolerance to some antimicrobial compounds and heavy metal ions, especially those in the toxic cation group. Comparative transcriptomics showed significant variation in the expression levels of up to 189 chromosomal genes due to the presence of single plasmids and 435 unique chromosomal genes that were resultant of the activity of all plasmids, which may suggest that the observed phenotypic changes are not only the result of a direct action of their own genes but also originate from indirect actions through crosstalk between plasmids and the chromosome. The data obtained here indicate that plasmid maintenance leads to the development of important mechanisms of global gene regulation that provide changes in the central metabolic pathways and adaptive properties of L. lactis and suggest the possibility of a similar phenomenon among other groups of bacteria.
Collapse
Affiliation(s)
- Katarzyna Kosiorek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences (IBB PAS), Pawińskiego 5a, 02-106 Warsaw, Poland
| | | | - Marek Skoneczny
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences (IBB PAS), Pawińskiego 5a, 02-106 Warsaw, Poland
| | | |
Collapse
|
4
|
Song Q, Wu H, Zhang P, Tian K, Zhu H, Qiao J. LssR plays a positive regulatory role in acid and nisin tolerance response of Lactococcus lactis. J Dairy Sci 2022; 105:6483-6498. [PMID: 35840402 DOI: 10.3168/jds.2022-21842] [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: 01/19/2022] [Accepted: 04/14/2022] [Indexed: 11/19/2022]
Abstract
In Lactococcus lactis, different regulation mechanisms can be activated to overcome the effects of adverse environmental stresses. Here, a TetR family regulator LssR was demonstrated as a positive regulator in the activation of the mechanisms involved in acid and nisin tolerance of L. lactis. The deletion of lssR led to the reduction of tolerance of L. lactis NZ9000 to nisin and acid stress, and the survival rates of NZ9000 under nisin and acid stress were roughly 20-fold, 10-fold (pH 3.0, hydrochloric acid), and 8.9-fold (pH 4.0, lactic acid) of the lssR mutant NZΔlssR, respectively. Moreover, the lssR mutant NZΔlssR also displayed a lower intracellular pH stability and a changed cell surface morphology. Subsequently, transcriptome analysis revealed that genes related to the arginine deiminase pathway, the surface polysaccharides biosynthesis, carbohydrates transport and metabolism, multidrug resistance, cell repair proteins and chaperones were predominantly down transcribed in NZΔlssR. The transcript levels of the arginine deiminase pathway and the surface polysaccharides biosynthesis-associated genes under acid and nisin stresses were compared between the wild type NZ9000 and NZΔlssR using real-time fluorescence quantitative PCR. It revealed that the arginine deiminase pathway genes (arcD1C1C2T) and the surface polysaccharides biosynthesis genes (cgT, gmhB, gmhA, hddA, tagH and tarS) were proposed to be the main regulatory mechanisms of LssR in response to the acid and nisin stresses. Overall, the important role of LssR in the acid and nisin stresses response was demonstrated and the putative regulation mechanism of LssR was revealed.
Collapse
Affiliation(s)
- Qianqian Song
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Hao Wu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; Zhejiang Shaoxing Research Institute of Tianjin University, Shaoxing 312300, China
| | - Peng Zhang
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Kairen Tian
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Hongji Zhu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Jianjun Qiao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; Zhejiang Shaoxing Research Institute of Tianjin University, Shaoxing 312300, China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China; SynBio Research Platform Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
| |
Collapse
|
5
|
Tarazona NA, Hernández-Arriaga AM, Kniewel R, Prieto MA. Phasin interactome reveals the interplay of PhaF with the polyhydroxyalkanoate transcriptional regulatory protein PhaD in Pseudomonas putida. Environ Microbiol 2020; 22:3922-3936. [PMID: 32705785 PMCID: PMC7590123 DOI: 10.1111/1462-2920.15175] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/16/2020] [Accepted: 07/21/2020] [Indexed: 01/12/2023]
Abstract
Phasin PhaF, a multifunctional protein associated with the surface of polyhydroxyalkanoate (PHA) granules that also interacts with the nucleoid, contributes significantly to PHA biogenesis in pseudomonads. As a protein present on the surface of PHA granules, PhaF participates in granule stabilization and segregation, whereas its deletion has a notable impact on overall transcriptome, PHA accumulation and cell physiology, suggesting more extensive functions besides solely being a granule structural protein. Here, we followed a systematic approach to detect potential interactions of PhaF with other components of the cell, which could pinpoint unexplored functions of PhaF in the regulation of PHA production. We determined the PhaF interactome in Pseudomonas putida KT2440 via pull‐down‐mass spectrometry (PD‐MS) experiments. PhaF complexed with PHA‐related proteins, phasin PhaI and the transcriptional regulator PhaD, interactions that were verified to be direct using in vivo two‐hybrid analysis. The determination of the PHA granule proteome showed that PhaI and three other potential PhaF interacting partners, but not PhaD, were granule‐associated proteins. Analysis of the interaction of PhaF and PhaD with the phaI promoter by EMSA suggested a new role for PhaF in interacting with PhaD and raises new questions on the regulatory system controlling pha gene expression.
Collapse
Affiliation(s)
- Natalia A Tarazona
- Polymer Biotechnology Group, Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), Madrid, 28040, Spain
| | - Ana M Hernández-Arriaga
- Polymer Biotechnology Group, Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), Madrid, 28040, Spain.,Interdisciplinary Platform for Sustainable Plastics Towards a Circular Economy-CSIC (SusPlast-CSIC), Spain
| | - Ryan Kniewel
- Polymer Biotechnology Group, Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), Madrid, 28040, Spain.,Interdisciplinary Platform for Sustainable Plastics Towards a Circular Economy-CSIC (SusPlast-CSIC), Spain
| | - M Auxiliadora Prieto
- Polymer Biotechnology Group, Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), Madrid, 28040, Spain.,Interdisciplinary Platform for Sustainable Plastics Towards a Circular Economy-CSIC (SusPlast-CSIC), Spain
| |
Collapse
|
6
|
Ikegaya R, Shintani M, Kimbara K, Fakuda M, Yoshida N. Identification of a transcriptional regulator for oligotrophy-responsive promoter in Rhodococcus erythropolis N9T-4. Biosci Biotechnol Biochem 2020; 84:865-868. [PMID: 31884880 DOI: 10.1080/09168451.2019.1709792] [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: 10/25/2022]
Abstract
Two genes, aldA, and mnoA, encoding an NAD-dependent aliphatic dehydrogenase and N,N'-dimethyl-4-nitrosoaniline-dependent methanol dehydrogenase, respectively, are strongly expressed when Rhodococcus erythropolis N9T-4 is grown under oligotrophic conditions. In this study, we found a transcriptional regulator required for the transcription of both aldA and mnoA. The transcriptional regulator was also found to be essential for the oligotrophic growth of N9T-4.
Collapse
Affiliation(s)
- Ryoji Ikegaya
- Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan
| | - Masaki Shintani
- Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan
| | - Kazuhide Kimbara
- Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan
| | | | - Nobuyuki Yoshida
- Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan
| |
Collapse
|
7
|
Kasai D. Poly( cis-1,4-isoprene)-cleavage enzymes from natural rubber-utilizing bacteria. Biosci Biotechnol Biochem 2020; 84:1089-1097. [PMID: 32114907 DOI: 10.1080/09168451.2020.1733927] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Natural rubber and synthetic poly(cis-1,4-isoprene) are used industrially in the world. Microbial utilization for the isoprene rubbers has been reported in gram-positive and gram-negative bacteria. Poly(cis-1,4-isoprene)-cleavage enzymes that are secreted by rubber-utilizing bacteria cleave the poly(cis-1,4-isoprene) chain to generate low-molecular-weight oligo(cis-1,4-isoprene) derivatives containing aldehyde and ketone groups. The resulting products are converted to the compounds including carboxyl groups, which could then be further catabolized through β-oxidation pathway. One of poly(cis-1,4-isoprene)-cleavage enzymes is latex-clearing protein (Lcp) that was found in gram-positive rubber degraders including Streptomyces, Gordonia, Rhodococcus, and Nocardia species. The other one is rubber oxygenase A and B (RoxA/RoxB) which have been identified from gram-negative rubber degraders such as Steroidobacter cummioxidans and Rhizobacter gummiphilus. Recently, the transcriptional regulation mechanisms for Lcp-coding genes in gram-positive bacteria have been characterized. Here, the current knowledge of genes and enzymes for the isoprene rubber catabolism were summarized.
Collapse
Affiliation(s)
- Daisuke Kasai
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Japan
| |
Collapse
|
8
|
Hingston P, Brenner T, Truelstrup Hansen L, Wang S. Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions. Toxins (Basel) 2019; 11:toxins11070426. [PMID: 31330827 PMCID: PMC6669625 DOI: 10.3390/toxins11070426] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 01/31/2023] Open
Abstract
Listeria monocytogenes strains are known to harbour plasmids that confer resistance to sanitizers, heavy metals, and antibiotics; however, very little research has been conducted into how plasmids may influence L. monocytogenes’ ability to tolerate food-related stresses. To investigate this, a library (n = 93) of L. monocytogenes plasmid sequences were compared. Plasmid sequences were divided into two groups (G1 and G2) based on a repA phylogeny. Twenty-six unique plasmid types were observed, with 13 belonging to each of the two repA-based groups. G1 plasmids were significantly (p < 0.05) smaller than G2 plasmids but contained a larger diversity of genes. The most prevalent G1 plasmid (57,083 bp) was observed in 26 strains from both Switzerland and Canada and a variety of serotypes. Quantitative PCR (qPCR) revealed a >2-fold induction of plasmid-contained genes encoding an NADH peroxidase, cadmium ATPase, multicopper oxidase, and a ClpL chaperone protein during growth under salt (6% NaCl) and acid conditions (pH 5) and ProW, an osmolyte transporter, under salt stress conditions. No differences in salt and acid tolerance were observed between plasmid-cured and wildtype strains. This work highlights the abundance of specific plasmid types among food-related L. monocytogenes strains, the unique characteristics of G1 and G2 plasmids, and the possible contributions of plasmids to L. monocytogenes tolerance to food-related stresses.
Collapse
Affiliation(s)
- Patricia Hingston
- Department of Food, Nutrition and Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Thomas Brenner
- Department of Food, Nutrition and Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | | | - Siyun Wang
- Department of Food, Nutrition and Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| |
Collapse
|
9
|
Murarka P, Bagga T, Singh P, Rangra S, Srivastava P. Isolation and identification of a TetR family protein that regulates the biodesulfurization operon. AMB Express 2019; 9:71. [PMID: 31127394 PMCID: PMC6534649 DOI: 10.1186/s13568-019-0801-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 05/16/2019] [Indexed: 11/10/2022] Open
Abstract
Biodesulfurization helps in removal of sulfur from organosulfur present in petroleum fractions. All microorganisms isolated to date harbor a desulfurization operon consisting of three genes dszA, -B and -C which encode for monooxygenases (DszA & C) and desulfinase (DszB). Most of the studies have been carried out using dibenzothiophene as the model organosulfur compound, which is converted into 2 hydroxybiphenyl by a 4S pathway which maintains the calorific value of fuel. There are few studies reported on the regulation of this operon. However, there are no reports on the proteins which can enhance the activity of the operon. In the present study, we used in vitro and in vivo methods to identify a novel TetR family transcriptional regulator from Gordonia sp. IITR100 which functions as an activator of the dsz operon. Activation by TetR family regulator resulted in enhanced levels of desulfurization enzymes in Gordonia sp. IITR100. Activation was observed only when the 385 bp full length promoter was used. Upstream sequences between - 385 and - 315 were found to be responsible for activation. We provide evidence that the TetR family transcription regulator serves as an activator in other biodesulfurizing microorganisms such as Rhodococcus erythropolis IGTS8 and heterologous host Escherichia coli. This is the first report on the isolation of a possible transcriptional regulator that activates the desulfurization operon resulting in improved biodesulfurization.
Collapse
|
10
|
Glycerol metabolism and its regulation in lactic acid bacteria. Appl Microbiol Biotechnol 2019; 103:5079-5093. [DOI: 10.1007/s00253-019-09830-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/02/2019] [Accepted: 04/04/2019] [Indexed: 01/09/2023]
|
11
|
Ball AS, van Kessel JC. The master quorum-sensing regulators LuxR/HapR directly interact with the alpha subunit of RNA polymerase to drive transcription activation in Vibrio harveyi and Vibrio cholerae. Mol Microbiol 2019; 111:1317-1334. [PMID: 30742725 DOI: 10.1111/mmi.14223] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2019] [Indexed: 12/19/2022]
Abstract
In Vibrio species, quorum sensing controls gene expression for numerous group behaviors, including bioluminescence production, biofilm formation, virulence factor secretion systems, and competence. The LuxR/HapR master quorum-sensing regulators activate expression of hundreds of genes in response to changes in population densities. The mechanism of transcription activation by these TetR-type transcription factors is unknown, though LuxR DNA binding sites that lie in close proximity to the -35 region of the promoter are required for activation at some promoters. Here, we show that Vibrio harveyi LuxR directly interacts with RNA polymerase to activate transcription of the luxCDABE bioluminescence genes. LuxR interacts with RNA polymerase in vitro and in vivo and specifically interacts with both the N- and C-terminal domains of the RNA polymerase α-subunit. Amino acid substitutions in the RNAP interaction domain on LuxR decrease interactions between LuxR and the α-subunit and result in defects in transcription activation of quorum-sensing genes in vivo. The RNAP-LuxR interaction domain is conserved in Vibrio cholerae HapR and is required for activation of the HapR-regulated gene hapA. Our findings support a model in which LuxR/HapR bind proximally to RNA polymerase to drive transcription initiation at a subset of quorum-sensing genes in Vibrio species.
Collapse
Affiliation(s)
- Alyssa S Ball
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | | |
Collapse
|
12
|
DNA Binding and Sensor Specificity of FarR, a Novel TetR Family Regulator Required for Induction of the Fatty Acid Efflux Pump FarE in Staphylococcus aureus. J Bacteriol 2019; 201:JB.00602-18. [PMID: 30455282 DOI: 10.1128/jb.00602-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 11/12/2018] [Indexed: 12/18/2022] Open
Abstract
Divergent genes in Staphylococcus aureus USA300 encode the efflux pump FarE and TetR family regulator FarR, which confer resistance to antimicrobial unsaturated fatty acids. To study their regulation, we constructed USA300 ΔfarER, which exhibited a 2-fold reduction in MIC of linoleic acid. farE expressed from its native promoter on pLIfarE conferred increased resistance to USA300 but not USA300 ΔfarER Complementation of USA300 ΔfarER with pLIfarR also had no effect, whereas resistance was restored with pLIfarER or through ectopic expression of farE In electrophoretic mobility shift assays, FarR bound to three different oligonucleotide probes that each contained a TAGWTTA motif, occurring as (i) a singular motif overlapping the -10 element of the P farR promoter, (ii) in palindrome PAL1 immediately in the 3' direction of P farR , or (iii) within PAL2 upstream of the predicted P farE promoter. FarR autorepressed its expression through cooperative binding to PAL1 and the adjacent TAGWTTA motif in P farR Consistent with reports that S. aureus does not metabolize fatty acids through acyl coenzyme A (acyl-CoA) intermediates, DNA binding activity of FarR was not affected by linoleoyl-CoA. Conversely, induction of farE required fatty acid kinase FakA, which catalyzes the first metabolic step in the incorporation of unsaturated fatty acids into phospholipid. We conclude that FarR is needed to promote the expression of farE while strongly autorepressing its own expression, and our data are consistent with a model whereby FarR interacts with a FakA-dependent product of exogenous fatty acid metabolism to ensure that efflux only occurs when the metabolic capacity for incorporation of fatty acid into phospholipid is exceeded.IMPORTANCE Here, we describe the DNA binding and sensor specificity of FarR, a novel TetR family regulator (TFR) in Staphylococcus aureus Unlike the majority of TFRs that have been characterized, which function to repress a divergently transcribed gene, we find that FarR is needed to promote expression of the divergently transcribed farE gene, encoding a resistance-nodulation-division (RND) family efflux pump that is induced in response to antimicrobial unsaturated fatty acids. Induction of farE was dependent on the function of the fatty acid kinase FakA, which catalyzes the first metabolic step in the incorporation of exogenous unsaturated fatty acids into phospholipid. This represents a novel example of TFR function.
Collapse
|
13
|
Jiang M, Yin M, Wu S, Han X, Ji K, Wen M, Lu T. GdmRIII, a TetR Family Transcriptional Regulator, Controls Geldanamycin and Elaiophylin Biosynthesis in Streptomyces autolyticus CGMCC0516. Sci Rep 2017; 7:4803. [PMID: 28684749 PMCID: PMC5500506 DOI: 10.1038/s41598-017-05073-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 05/24/2017] [Indexed: 11/13/2022] Open
Abstract
Geldanamycin and elaiophylin are co-produced in several Streptomyces strains. However, the regulation of their biosynthesis is not fully understood yet. Herein the function of a TetR family regulator GdmRIII, which is located in the biosynthetic gene cluster of geldanamycin, was studied to understand the regulatory mechanism of geldanamycin biosynthesis in Streptomyces autolyticus CGMCC0516. The production of geldanamycin decreased substantially in a ΔgdmRIII mutant and the yield of three compounds which were thought to be geldanamycin congeners greatly increased. Surprisingly, the structural elucidation of these compounds showed that they were elaiophylin and its analogues, which implied that GdmRIII not only played a positive regulatory role in the biosynthesis of geldanamycin, but also played a negative role in elaiophylin biosynthesis. GdmRIII affected the expression of multiple genes in both gene clusters, and directly regulated the expression of gdmM, gdmN, and elaF by binding to the promoter regions of these three genes. A conserved non-palindromic sequence was found among the binding sites of elaF. Our findings suggested that the biosynthetic pathways of geldanamycin and elaiophylin were connected through GdmRIII, which might provide a way for Streptomyces to coordinate the biosynthesis of these compounds for better adapting to environment changes.
Collapse
Affiliation(s)
- MingXing Jiang
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China
| | - Min Yin
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China
| | - ShaoHua Wu
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China
| | - XiuLin Han
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China
| | - KaiYan Ji
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China
| | - MengLiang Wen
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China.
| | - Tao Lu
- Yunnan Institute of Microbiology, Yunnan University, 2 North Cui Hu Road, Kunming, Yunnan, 650091, China.
| |
Collapse
|
14
|
Crystal Structure of Fad35R from Mycobacterium tuberculosis H37Rv in the Apo-State. PLoS One 2015; 10:e0124333. [PMID: 25938298 PMCID: PMC4418694 DOI: 10.1371/journal.pone.0124333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 03/04/2015] [Indexed: 11/19/2022] Open
Abstract
Fad35R from Mycobacterium tuberculosis binds to the promoter site of Fad35 operon and its DNA binding activities are reduced in the presence of tetracycline and palmitoyl-CoA. We resolved the crystal structure of Fad35R using single-wavelength anomalous diffraction method (SAD). Fad35R comprises canonical DNA binding domain (DBD) and ligand binding domain (LBD), but displays several distinct structural features. Two recognition helices of two monomers in the homodimer are separated by ~ 48 Å and two core triangle-shaped ligand binding cavities are well exposed to solvent. Structural comparison with DesT and QacR structures suggests that ligand binding-induced movement of α7, which adopts a straight conformation in the Fad35R, may be crucial to switch the conformational states between repressive and derepressive forms. Two DBDs are packed asymmetrically, creating an alternative dimer interface which coincides with the possible tetramer interface that connects the two canonical dimers. Quaternary state of alternative dimer mimics a closed-state structure in which two recognition helices are distanced at ~ 35 Å and ligand binding pockets are inaccessible. Results of biophysical studies indicate that Fad35R has the propensity to oligomerize in solution in the presence of tetracycline. We present the first structure of a FadR homologue from mycobacterium and the structure reveals DNA and ligand binding features of Fad35R and also provides a view on alternative quaternary states that mimic open and closed forms of the regulator.
Collapse
|
15
|
Inducible Expression of a Resistance-Nodulation-Division-Type Efflux Pump in Staphylococcus aureus Provides Resistance to Linoleic and Arachidonic Acids. J Bacteriol 2015; 197:1893-905. [PMID: 25802299 DOI: 10.1128/jb.02607-14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Accepted: 03/17/2015] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Although Staphylococcus aureus is exposed to antimicrobial fatty acids on the skin, in nasal secretions, and in abscesses, a specific mechanism of inducible resistance to this important facet of innate immunity has not been identified. Here, we have sequenced the genome of S. aureus USA300 variants selected for their ability to grow at an elevated concentration of linoleic acid. The fatty acid-resistant clone FAR7 had a single nucleotide polymorphism resulting in an H₁₂₁Y substitution in an uncharacterized transcriptional regulator belonging to the AcrR family, which was divergently transcribed from a gene encoding a member of the resistance-nodulation-division superfamily of multidrug efflux pumps. We named these genes farR and farE, for regulator and effector of fatty acid resistance, respectively. Several lines of evidence indicated that FarE promotes efflux of antimicrobial fatty acids and is regulated by FarR. First, expression of farE was strongly induced by arachidonic and linoleic acids in an farR-dependent manner. Second, an H₁₂₁Y substitution in FarR resulted in increased expression of farE and was alone sufficient to promote increased resistance of S. aureus to linoleic acid. Third, inactivation of farE resulted in a significant reduction in the inducible resistance of S. aureus to the bactericidal activity of 100 μM linoleic acid, increased accumulation of [(14)C]linoleic acid by growing cells, and severely impaired growth in the presence of nonbactericidal concentrations of linoleic acid. Cumulatively, these findings represent the first description of a specific mechanism of inducible resistance to antimicrobial fatty acids in a Gram-positive pathogen. IMPORTANCE Staphylococcus aureus colonizes approximately 25% of humans and is a leading cause of human infectious morbidity and mortality. To persist on human hosts, S. aureus must have intrinsic defense mechanisms to cope with antimicrobial fatty acids, which comprise an important component of human innate defense mechanisms. We have identified a novel pair of genes, farR and farE, that constitute a dedicated regulator and effector of S. aureus resistance to linoleic and arachidonic acids, which are major fatty acids in human membrane phospholipid. Expression of farE, which encodes an efflux pump, is induced in an farR-dependent mechanism, in response to these antimicrobial fatty acids that would be encountered in a tissue abscess.
Collapse
|
16
|
Taylor DL, Ante VM, Bina XR, Howard MF, Bina JE. Substrate-dependent activation of the Vibrio cholerae vexAB RND efflux system requires vexR. PLoS One 2015; 10:e0117890. [PMID: 25695834 PMCID: PMC4335029 DOI: 10.1371/journal.pone.0117890] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 01/05/2015] [Indexed: 01/08/2023] Open
Abstract
Vibrio cholerae encodes six resistance-nodulation-division (RND) efflux systems which function in antimicrobial resistance, virulence factor production, and intestinal colonization. Among the six RND efflux systems, VexAB exhibited broad substrate specificity and played a predominant role in intrinsic antimicrobial resistance. The VexAB system was encoded in an apparent three gene operon that included vexR; which encodes an uncharacterized TetR family regulator. In this work we examined the role of vexR in vexRAB expression. We found that VexR bound to the vexRAB promoter and vexR deletion resulted in decreased vexRAB expression and increased susceptibility to VexAB antimicrobial substrates. Substrate-dependent induction of vexRAB was dependent on vexR and episomal vexR expression provided a growth advantage in the presence of the VexAB substrate deoxycholate. The expression of vexRAB increased, in a vexR-dependent manner, in response to the loss of RND efflux activity. This suggested that VexAB may function to export intracellular metabolites. Support for this hypothesis was provided by data showing that vexRAB was upregulated in several metabolic mutants including tryptophan biosynthetic mutants that were predicted to accumulate indole. In addition, vexRAB was found to be upregulated in response to exogenous indole and to contribute to indole resistance. The collective results indicate that vexR is required for vexRAB expression in response to VexAB substrates and that the VexAB RND efflux system modulates the intracellular levels of metabolites that could otherwise accumulate to toxic levels.
Collapse
Affiliation(s)
- Dawn L. Taylor
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - Vanessa M. Ante
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - X. Renee Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - Mondraya F. Howard
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - James E. Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
17
|
Nguyen Le Minh P, de Cima S, Bervoets I, Maes D, Rubio V, Charlier D. Ligand binding specificity of RutR, a member of the TetR family of transcription regulators in Escherichia coli. FEBS Open Bio 2015; 5:76-84. [PMID: 25685666 PMCID: PMC4325133 DOI: 10.1016/j.fob.2015.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 01/14/2015] [Accepted: 01/14/2015] [Indexed: 02/01/2023] Open
Abstract
RutR, a TetR-family member in E. coli, exerts both positive and negative regulation. The crystal structure of the RutR mutant W167 protein without bound uracil is determined. Comparison of uracil-free and uracil-bound RutR reveal structural transitions. L74, W77, W167 and L78 are important for binding of the uracil effector. L78 is crucial for the specificity for uracil, preventing thymine binding.
RutR is a member of the large family of TetR transcriptional regulators in Escherichiacoli. It was originally discovered as the regulator of the rutABCDEFG operon encoding a novel pathway for pyrimidine utilization, but its highest affinity target is the control region of the carAB operon, encoding carbamoylphosphate synthase. Unlike most other TetR-like regulators, RutR exerts both positive and negative effects on promoter activity. Furthermore, RutR exhibits a very narrow ligand binding specificity, unlike the broad effector specificity that characterizes some of the well-studied multidrug resistance regulators of the family. Here we focus on ligand binding and ligand specificity of RutR. We construct single alanine substitution mutants of amino acid residues of the ligand-binding pocket, study their effect on in vitro DNA binding in absence and presence of potential ligands, and analyse their effect on positive regulation of the carP1 promoter and negative autoregulation in vivo. Although RutR structures have been determined previously, they were deposited in the Protein Data Bank without accompanying publications. All of them have uracil bound in the effector-binding site, representing the inactive form of the regulator. We determined the crystal structure of an unliganded mutant RutR protein and provide a structural basis for the use of uracil as sole effector molecule and the exclusion of the very similar thymine from the ligand-binding pocket.
Collapse
Affiliation(s)
- Phu Nguyen Le Minh
- Research Group of Microbiology, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussel, Belgium ; Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Cientificas (IBV-CSIC), Centro de Investigación Biomédicaen Red de Enfermedades Raras (CIBERER-ISCIII), C/Jaime Roig 11, E-46010 Valencia, Spain
| | - Sergio de Cima
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Cientificas (IBV-CSIC), Centro de Investigación Biomédicaen Red de Enfermedades Raras (CIBERER-ISCIII), C/Jaime Roig 11, E-46010 Valencia, Spain
| | - Indra Bervoets
- Research Group of Microbiology, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussel, Belgium
| | - Dominique Maes
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussel, Belgium
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Cientificas (IBV-CSIC), Centro de Investigación Biomédicaen Red de Enfermedades Raras (CIBERER-ISCIII), C/Jaime Roig 11, E-46010 Valencia, Spain
| | - Daniel Charlier
- Research Group of Microbiology, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussel, Belgium
| |
Collapse
|
18
|
Wei D, Wang M, Jiang B, Shi J, Hao J. Role of dihydroxyacetone kinases I and II in the dha regulon of Klebsiella pneumoniae. J Biotechnol 2014; 177:13-9. [DOI: 10.1016/j.jbiotec.2014.02.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/11/2014] [Accepted: 02/14/2014] [Indexed: 10/25/2022]
|
19
|
Abstract
The most common prokaryotic signal transduction mechanisms are the one-component systems in which a single polypeptide contains both a sensory domain and a DNA-binding domain. Among the >20 classes of one-component systems, the TetR family of regulators (TFRs) are widely associated with antibiotic resistance and the regulation of genes encoding small-molecule exporters. However, TFRs play a much broader role, controlling genes involved in metabolism, antibiotic production, quorum sensing, and many other aspects of prokaryotic physiology. There are several well-established model systems for understanding these important proteins, and structural studies have begun to unveil the mechanisms by which they bind DNA and recognize small-molecule ligands. The sequences for more than 200,000 TFRs are available in the public databases, and genomics studies are identifying their target genes. Three-dimensional structures have been solved for close to 200 TFRs. Comparison of these structures reveals a common overall architecture of nine conserved α helices. The most important open question concerning TFR biology is the nature and diversity of their ligands and how these relate to the biochemical processes under their control.
Collapse
|
20
|
Erni B. The bacterial phosphoenolpyruvate: sugar phosphotransferase system (PTS): an interface between energy and signal transduction. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2012. [DOI: 10.1007/s13738-012-0185-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
21
|
Genome context as a predictive tool for identifying regulatory targets of the TetR family transcriptional regulators. PLoS One 2012; 7:e50562. [PMID: 23226315 PMCID: PMC3511530 DOI: 10.1371/journal.pone.0050562] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/23/2012] [Indexed: 01/21/2023] Open
Abstract
TetR family transcriptional regulators (TFRs) are found in most bacteria and archea. Most of the family members that have been investigated to date are repressors of their target genes, and the majority of these, like the well-characterized protein TetR, regulate genes that encode transmembrane efflux pumps. In many cases repression by TFR proteins is reversed through the direct binding of a small-molecule ligand. The number of TFRs in the public database has grown rapidly as a result of genome sequencing and there are now thousands of family members; however virtually nothing is known about the biology and biochemistry they regulate. Generally applicable methods for predicting their regulatory targets would assist efforts to characterize the family. Here, we investigate chromosomal context of 372 TFRs from three Streptomyces species. We find that the majority (250 TFRs) are transcribed divergently from one neighboring gene, as is the case for TetR and its target tetA. We explore predicted target gene product identity and intergenic separation to see which either correlates with a direct regulatory relationship. While intergenic separation is a critical factor in regulatory prediction the identity of the putative target gene product is not. Our data suggest that those TFRs that are <200 bp from their divergently oriented neighbors are most likely to regulate them. These target genes include membrane proteins (26% of which 22% are probable membrane-associated pumps), enzymes (60%), other proteins such as transcriptional regulators (1%), and proteins having no predictive sequence motifs (13%). In addition to establishing a solid foundation for identifying targets for TFRs of unknown function, our analysis demonstrates a much greater diversity of TFR-regulated biochemical functions.
Collapse
|
22
|
Anand S, Singh V, Singh AK, Mittal M, Datt M, Subramani B, Kumaran S. Equilibrium binding and kinetic characterization of putative tetracycline repressor family transcription regulator Fad35R from Mycobacterium tuberculosis. FEBS J 2012; 279:3214-28. [PMID: 22805491 DOI: 10.1111/j.1742-4658.2012.08707.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fatty acids play critical role in the survival and virulence of Mycobacterium tuberculosis (Mtb). Activation of fatty acids by acyl-CoA synthetases (Fad) into fatty acyl-CoA is the first and one of the crucial steps in fatty acid metabolism. Mtb possesses 36 fatty acyl-CoA synthetases, unlike Escherichia coli, which has single enzyme. However, the mechanisms by which the expression of these multiple Fad genes is regulated remain uncharacterized. We characterized the DNA- and ligand-binding properties of a putative tetracycline repressor family regulator, named Fad35R, located upstream of the Fad35 gene and ScoA-citE operon. We identified a palindromic regulatory motif upstream of Fad35 and characterized the binding of Fad35R to this motif. Equilibrium binding studies show that Fad35R binds to this motif with high affinity (K(d) ∼ 0.033 μm) and the specificity of binding was confirmed by an electromobility gel shift assay. Kinetic studies indicate that faster association (k(a,avg) ∼ 5.4 × 10(4) m(-1) · s(-1)) and slower dissociation rates (k(d,avg) ∼ 5.84 × 10(-4) s(-1)) confer higher affinity. The affinity for the promoter is maximum at 300 mm NaCl but decreases rapidly beyond this range. Ligand-binding studies indicate that Fad35R binds specifically to tetracycline and also binds to fatty acid derivatives. The promoter-binding affinity is decreased significantly in the presence of palmityl-CoA, suggesting that Fad35R can sense the levels of activated fatty acids and alter its DNA-binding activity. Our results suggest that Fad35R may be the functional homologue of FadR and controls the expression of genes in a metabolite-dependent manner.
Collapse
Affiliation(s)
- Sushma Anand
- Council of Scientific and Industrial Research, India, Institute of Microbial Technology, Chandigarh, India
| | | | | | | | | | | | | |
Collapse
|
23
|
Regulation of transcription by SMU.1349, a TetR family regulator, in Streptococcus mutans. J Bacteriol 2011; 193:6605-13. [PMID: 21965566 DOI: 10.1128/jb.06122-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The TetR family of transcriptional regulators is ubiquitous in bacteria, where it plays an important role in bacterial gene expression. Streptococcus mutans, a gram-positive pathogen considered to be the primary etiological agent in the formation of dental caries, encodes at least 18 TetR regulators. Here we characterized one such TetR regulator, SMU.1349, encoded by the TnSmu2 operon, which appeared to be acquired by the organism via horizontal gene transfer. SMU.1349 is transcribed divergently from the rest of the genes encoded by the operon. By the use of a transcriptional reporter system and semiquantitative reverse transcription-PCR (RT-PCR), we demonstrated that SMU.1349 activates the transcription of several genes that are encoded within the TnSmu2 operon. Gel mobility shift and DNase I footprinting assays with purified SMU.1349 protein demonstrated binding to the intergenic region between SMU.1349 and the TnSmu2 operon; therefore, SMU.1349 is directly involved in gene transcription. Using purified S. mutans RpoD and Escherichia coli RNA polymerase, we also demonstrated in an in vitro transcription assay that SMU.1349 could activate transcription from the TnSmu2 operon promoter. Furthermore, we showed that SMU.1349 could also repress transcription from its own promoter by binding to the intergenic region, suggesting that SMU.1349 acts as both an activator and a repressor. Thus, unlike most of the TetR family proteins, which generally function as transcriptional repressors, SMU.1349 is unique in that it can function as both.
Collapse
|
24
|
Nickel J, Irzik K, van Ooyen J, Eggeling L. The TetR-type transcriptional regulator FasR of Corynebacterium glutamicum controls genes of lipid synthesis during growth on acetate. Mol Microbiol 2011; 78:253-65. [PMID: 20923423 DOI: 10.1111/j.1365-2958.2010.07337.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The addition of fatty acids to either Escherichia coli or Bacillus subtilis elicits an elaborate cellular response of the lipid metabolism. We found that in Corynebacterium glutamicum the expression of accD1 encoding the β-subunit of the essential acetyl-CoA carboxylase is repressed in acetate-grown cells without the addition of fatty acids. The TetR-type transcriptional regulator NCgl2404, termed FasR, was identified and deleted. During growth on acetate, but not on glucose, 17 genes are differentially expressed in the deletion mutant, among them accD1, and fasA and fasB both encoding fatty acid synthases, which were upregulated. Determination of the 5' ends of accD1, fasA, fasB and accBC together with the use of isolated FasR protein identified the FasR binding site, fasO, which is located within the accD1 and fasA transcript initiation site thus blocking transcription by RNA polymerase binding directly. The identified fasO motif is present in C. efficiens or C. diphtheriae, too, and it is actually similarly positioned in these bacteria within the 5' ends of the accD1 and fasA transcripts, and a fasR orthologue is also present. The identification of the FasR-fasO system in Corynebacteriaceae might indicate a conserved transcriptional control of the unique lipid synthesis in these mycolic acid-containing bacteria.
Collapse
Affiliation(s)
- Jens Nickel
- Institute of Biotechnology 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | | | | | | |
Collapse
|
25
|
Yu Z, Reichheld SE, Savchenko A, Parkinson J, Davidson AR. A comprehensive analysis of structural and sequence conservation in the TetR family transcriptional regulators. J Mol Biol 2010; 400:847-64. [PMID: 20595046 DOI: 10.1016/j.jmb.2010.05.062] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 05/21/2010] [Accepted: 05/25/2010] [Indexed: 11/17/2022]
Abstract
The tetracycline repressor family transcriptional regulators (TFRs) are homodimeric DNA-binding proteins that generally act as transcriptional repressors. Their DNA-binding activity is allosterically inactivated by the binding of small-molecule ligands. TFRs constitute the third most frequently occurring transcriptional regulator family found in bacteria with more than 10,000 representatives in the nonredundant protein database. In addition, more than 100 unique TFR structures have been solved by X-ray crystallography. In this study, we have used computational and experimental approaches to reveal the variations and conservation present within TFRs. Although TFR structures are very diverse, we were able to identify a conserved central triangle in their ligand-binding domains that forms the foundation of the structure and the framework for the ligand-binding cavity. While the sequences of DNA-binding domains of TFRs are highly conserved across the whole family, the sequences of their ligand-binding domains are so diverse that pairwise sequence similarity is often undetectable. Nevertheless, by analyzing subfamilies of TFRs, we were able to identify distinct regions of conservation in ligand-binding domains that may be important for allostery. To aid in large-scale analyses of TFR function, we have developed a simple and reliable computational approach to predict TFR operator sequences, a temperature melt-based assay to measure DNA binding, and a generic ligand-binding assay that will likely be applicable to most TFRs. Finally, our analysis of TFR structures highlights their flexibility and provides insight into a conserved allosteric mechanism for this family.
Collapse
Affiliation(s)
- Zhou Yu
- Department of Molecular Genetics, University of Toronto, 4285 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada
| | | | | | | | | |
Collapse
|
26
|
de Eugenio LI, Galán B, Escapa IF, Maestro B, Sanz JM, García JL, Prieto MA. The PhaD regulator controls the simultaneous expression of thephagenes involved in polyhydroxyalkanoate metabolism and turnover inPseudomonas putidaKT2442. Environ Microbiol 2010; 12:1591-603. [DOI: 10.1111/j.1462-2920.2010.02199.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
27
|
Hasselt K, Sevvana M, Burkovski A, Muller YA. Crystallization and preliminary crystallographic analysis of the global nitrogen regulator AmtR from Corynebacterium glutamicum. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:1123-7. [PMID: 19923732 PMCID: PMC2777040 DOI: 10.1107/s174430910903663x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 09/10/2009] [Indexed: 11/10/2022]
Abstract
AmtR, a member of the TetR family of transcription regulators, is a global regulator of nitrogen control in Corynebacterium glutamicum. Unlike other TetR-family members, which are regulated by small-molecule effectors, AmtR is regulated by a protein called GlnK. It has been shown that a GlnK trimer has to become adenylylated prior to formation of a complex with AmtR. The physiological function of AmtR has been very well studied, but structural characterization of the mechanistic aspects of AmtR-regulated transcription has yet to be accomplished. AmtR has successfully been crystallized in space group P2(1)2(1)2, with six molecules in the asymmetric unit and unit-cell parameters a = 153.34, b = 163.10, c = 51.93 angstrom . Preliminary phases were obtained using Se-SAD.
Collapse
Affiliation(s)
- Kristin Hasselt
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Madhumati Sevvana
- Lehrstuhl für Biotechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, 91052 Erlangen, Germany
| | - Andreas Burkovski
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Yves A. Muller
- Lehrstuhl für Biotechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, 91052 Erlangen, Germany
| |
Collapse
|
28
|
Oberholzer AE, Schneider P, Siebold C, Baumann U, Erni B. Crystal structure of enzyme I of the phosphoenolpyruvate sugar phosphotransferase system in the dephosphorylated state. J Biol Chem 2009; 284:33169-76. [PMID: 19801641 DOI: 10.1074/jbc.m109.057612] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bacterial phosphoenolpyruvate (PEP) sugar phosphotransferase system mediates sugar uptake and controls the carbon metabolism in response to carbohydrate availability. Enzyme I (EI), the first component of the phosphotransferase system, consists of an N-terminal protein binding domain (EIN) and a C-terminal PEP binding domain (EIC). EI transfers phosphate from PEP by double displacement via a histidine residue on EIN to the general phosphoryl carrier protein HPr. Here we report the 2.4 A crystal structure of the homodimeric EI from Staphylococcus aureus. EIN consists of the helical hairpin HPr binding subdomain and the phosphorylatable betaalpha phospho-histidine (P-His) domain. EIC folds into an (betaalpha)(8) barrel. The dimer interface of EIC buries 1833 A(2) of accessible surface per monomer and contains two Ca(2+) binding sites per dimer. The structures of the S. aureus and Escherichia coli EI domains (Teplyakov, A., Lim, K., Zhu, P. P., Kapadia, G., Chen, C. C., Schwartz, J., Howard, A., Reddy, P. T., Peterkofsky, A., and Herzberg, O. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 16218-16223) are very similar. The orientation of the domains relative to each other, however, is different. In the present structure the P-His domain is docked to the HPr binding domain in an orientation appropriate for in-line transfer of the phosphate to the active site histidine of the acceptor HPr. In the E. coli structure the phospho-His of the P-His domain projects into the PEP binding site of EIC. In the S. aureus structure the crystallographic temperature factors are lower for the HPr binding domain in contact with the P-His domain and higher for EIC. In the E. coli structure it is the reverse.
Collapse
Affiliation(s)
- Anselm E Oberholzer
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | | | | | | | | |
Collapse
|
29
|
Zurbriggen A, Jeckelmann JM, Christen S, Bieniossek C, Baumann U, Erni B. X-ray structures of the three Lactococcus lactis dihydroxyacetone kinase subunits and of a transient intersubunit complex. J Biol Chem 2008; 283:35789-96. [PMID: 18957416 DOI: 10.1074/jbc.m804893200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Bacterial dihydroxyacetone (Dha) kinases do not exchange the ADP for ATP but utilize a subunit of the phosphoenolpyruvate carbohydrate phosphotransferase system for in situ rephosphorylation of a permanently bound ADP-cofactor. Here we report the 2.1-angstroms crystal structure of the transient complex between the phosphotransferase subunit DhaM of the phosphotransferase system and the nucleotide binding subunit DhaL of the Dha kinase of Lactococcus lactis, the 1.1-angstroms structure of the free DhaM dimer, and the 2.5-angstroms structure of the Dha-binding DhaK subunit. Conserved salt bridges and an edge-to-plane stacking contact between two tyrosines serve to orient DhaL relative to the DhaM dimer. The distance between the imidazole Nepsilon2 of the DhaM His-10 and the beta-phosphate oxygen of ADP, between which the gamma-phosphate is transferred, is 4.9 angstroms. An invariant arginine, which is essential for activity, is appropriately positioned to stabilize the gamma-phosphate in the transition state. The (betaalpha)4alpha fold of DhaM occurs a second time as a subfold in the DhaK subunit. By docking DhaL-ADP to this subfold, the nucleotide bound to DhaL and the C1-hydroxyl of Dha bound to DhaK are positioned for in-line transfer of phosphate.
Collapse
Affiliation(s)
- Andreas Zurbriggen
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, Bern CH-3012, Switzerland
| | | | | | | | | | | |
Collapse
|
30
|
Déméné H, Ducat T, De Guillen K, Birck C, Aymerich S, Kochoyan M, Declerck N. Structural mechanism of signal transduction between the RNA-binding domain and the phosphotransferase system regulation domain of the LicT antiterminator. J Biol Chem 2008; 283:30838-49. [PMID: 18682383 DOI: 10.1074/jbc.m805955200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LicT belongs to a family of bacterial transcriptional antiterminators, which control the expression of sugar-metabolizing operons in response to phosphorylations by the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Previous studies of LicT have revealed the structural basis of RNA recognition by the dimeric N-terminal co-antiterminator (CAT) domain on the one hand and the conformational changes undergone by the duplicated regulation domain (PRD1 and PRD2) upon activation on the other hand. To investigate the mechanism of signal transduction between the effector and regulation modules, we have undertaken the characterization of a fragment, including the CAT and PRD1 domains and the linker in-between. Comparative experiments, including RNA binding assays, NMR spectroscopy, limited proteolysis, analytical ultracentrifugation, and circular dichroism, were conducted on native CAT-PRD1 and on a constitutively active CAT-PRD1 mutant carrying a D99N substitution in PRD1. We show that in the native state, CAT-PRD1 behaves as a rather unstable RNA-binding deficient dimer, in which the CAT dimer interface is significantly altered and the linker region is folded as a trypsin-resistant helix. In the activated mutant form, the CAT-PRD1 linker becomes protease-sensitive, and the helix content decreases, and the CAT module adopts the same dimeric conformation as in isolated CAT, thereby restoring the affinity for RNA. From these results, we propose that a helix-to-coil transition in the linker acts as the structural relay triggered by the regulatory domain for remodeling the effector dimer interface. In essence, the structural mechanism modulating the LicT RNA antitermination activity is thus similar to that controlling the DNA binding activity of dimeric transcriptional regulators.
Collapse
Affiliation(s)
- Hélène Déméné
- CNRS UMR 5048, Centre de Biocimie Structurale, Montpellier Cedex, France.
| | | | | | | | | | | | | |
Collapse
|
31
|
Daam J, Mehdaoui K, Klotzsche M, Pfleiderer K, Berens C, Hillen W. Functionally important residues of the Tet repressor inducing peptide TIP determined by a complete mutational analysis. Gene 2008; 423:201-6. [PMID: 18672042 DOI: 10.1016/j.gene.2008.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 06/10/2008] [Accepted: 07/03/2008] [Indexed: 01/31/2023]
Abstract
Tet repressor (TetR) is widely used to control gene expression in pro- and eukaryotes. The mechanism of induction by its natural inducer tetracycline is well characterized. A 16-mer oligopeptide, called TIP, fused to thioredoxin A (TrxA) of Escherichia coli is an artificial inducer of TetR. We analyzed the sequence requirements of TIP by directed and random single amino acid substitutions and identified residues important for TetR induction. An alanine scanning analysis of the first twelve residues showed that all except the ones at position eleven and twelve are important for induction. A randomization of residues at positions one to twelve of TIP revealed the properties of each residue necessary for induction. These further insights into the specificity of TIP-TetR interaction are discussed in the light of the X-ray structure of the [TetR-TIP] complex. The last four residues of TIP contribute indirectly to TetR induction by increasing the steady-state level of the fusion protein. TIP mutants fused N-terminally or C-terminally to TrxA in E. coli induce with the same efficiency indicating identical binding and induction mechanisms, and the lack of contribution from TrxA.
Collapse
Affiliation(s)
- Janko Daam
- Lehrstuhl für Mikrobiologie, Department Biologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | | | | | | | | | | |
Collapse
|
32
|
Willems AR, Tahlan K, Taguchi T, Zhang K, Lee ZZ, Ichinose K, Junop MS, Nodwell JR. Crystal structures of the Streptomyces coelicolor TetR-like protein ActR alone and in complex with actinorhodin or the actinorhodin biosynthetic precursor (S)-DNPA. J Mol Biol 2008; 376:1377-87. [PMID: 18207163 DOI: 10.1016/j.jmb.2007.12.061] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 12/19/2007] [Accepted: 12/21/2007] [Indexed: 11/24/2022]
Abstract
Actinorhodin, an antibiotic produced by Streptomyces coelicolor, is exported from the cell by the ActA efflux pump. actA is divergently transcribed from actR, which encodes a TetR-like transcriptional repressor. We showed previously that ActR represses transcription by binding to an operator from the actA/actR intergenic region. Importantly, actinorhodin itself or various actinorhodin biosynthetic intermediates can cause ActR to dissociate from its operator, leading to derepression. This suggests that ActR may mediate timely self-resistance to an endogenously produced antibiotic by responding to one of its biosynthetic precursors. Here, we report the structural basis for this precursor-mediated derepression with crystal structures of homodimeric ActR by itself and in complex with either actinorhodin or the actinorhodin biosynthetic intermediate (S)-DNPA [4-dihydro-9-hydroxy-1-methyl-10-oxo-3-H-naphtho-[2,3-c]-pyran-3-(S)-acetic acid]. The ligand-binding tunnel in each ActR monomer has a striking hydrophilic/hydrophobic/hydrophilic arrangement of surface residues that accommodate either one hexacyclic actinorhodin molecule or two back-to-back tricyclic (S)-DNPA molecules. Moreover, our work also reveals the strongest structural evidence to date that TetR-mediated antibiotic resistance may have been acquired from an antibiotic-producer organism.
Collapse
Affiliation(s)
- A R Willems
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Ahn SK, Tahlan K, Yu Z, Nodwell J. Investigation of transcription repression and small-molecule responsiveness by TetR-like transcription factors using a heterologous Escherichia coli-based assay. J Bacteriol 2007; 189:6655-64. [PMID: 17644591 PMCID: PMC2045172 DOI: 10.1128/jb.00717-07] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The SCO7222 protein and ActR are two of approximately 150 TetR-like transcription factors encoded in the Streptomyces coelicolor genome. Using bioluminescence as a readout, we have developed Escherichia coli-based biosensors that accurately report the regulatory activity of these proteins and used it to investigate their interactions with DNA and small-molecule ligands. We found that the SCO7222 protein and ActR repress the expression of their putative target genes, SCO7223 and actII-ORF2 (actA), respectively, by interacting with operator sequence in the promoters. The operators recognized by the two proteins are related such that O(7223) (an operator for SCO7223) could be bound by both the SCO7222 protein and ActR with similar affinities. In contrast, O(act) (an operator for actII-ORF2) was bound tightly by ActR and more weakly by the SCO7222 protein. We demonstrated ligand specificity of these proteins by showing that while TetR (but not ActR or the SCO7222 protein) interacts with tetracyclines, ActR (but not TetR or the SCO7222 protein) interacts with actinorhodin and related molecules. Through operator-targeted mutagenesis, we found that at least two nucleotide changes in O(7223) were required to disrupt its interaction with SCO7222 protein, while ActR was more sensitive to changes on O(act). Most importantly, we found that the interaction of each protein with wild-type and mutant operator sequences in vivo and in vitro correlated perfectly. Our data suggest that E. coli-based biosensors of this type should be broadly applicable to TetR-like transcription factors.
Collapse
Affiliation(s)
- Sang Kyun Ahn
- Department of Biochemistry and Biomedical Sciences, HSC 4H21, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada
| | | | | | | |
Collapse
|
34
|
Kloosterman TG, van der Kooi-Pol MM, Bijlsma JJE, Kuipers OP. The novel transcriptional regulator SczA mediates protection against Zn2+ stress by activation of the Zn2+-resistance gene czcD in Streptococcus pneumoniae. Mol Microbiol 2007; 65:1049-63. [PMID: 17640279 DOI: 10.1111/j.1365-2958.2007.05849.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Maintenance of the intracellular homeostasis of metal ions is important for the virulence of many bacterial pathogens. Here, we demonstrate that the czcD gene of the human pathogen Streptococcus pneumoniae is involved in resistance against Zn2+, and that its transcription is induced by the transition-metal ions Zn2+, Co2+ and Ni2+. Upstream of czcD a gene was identified, encoding a novel TetR family regulator, SczA, that is responsible for the metal ion-dependent activation of czcD expression. Transcriptome analyses revealed that in a sczA mutant expression of czcD, a gene encoding a MerR-family transcriptional regulator and a gene encoding a zinc-containing alcohol dehydrogenase (adhB) were downregulated. Activation of the czcD promoter by SczA is shown to proceed by Zn2+-dependent binding of SczA to a conserved DNA motif. In the absence of Zn2+, SczA binds to a second site in the czcD promoter, thereby fully blocking czcD expression. This is the first example of a metalloregulatory protein belonging to the TetR family that has been described. The presence in S. pneumoniae of the Zn2+-resistance system characterized in this study might reflect the need for adjustment to a fluctuating Zn2+ pool encountered by this pathogen during infection of the human body.
Collapse
Affiliation(s)
- Tomas G Kloosterman
- Department of Molecular Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, PO Box 14, 9750 AA Haren, The Netherlands
| | | | | | | |
Collapse
|
35
|
Folster JP, Dhulipala V, Nicholas RA, Shafer WM. Differential regulation of ponA and pilMNOPQ expression by the MtrR transcriptional regulatory protein in Neisseria gonorrhoeae. J Bacteriol 2007; 189:4569-77. [PMID: 17483228 PMCID: PMC1913451 DOI: 10.1128/jb.00286-07] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neisseria gonorrhoeae utilizes the mtrCDE-encoded efflux pump system to resist not only host-derived, hydrophobic antimicrobials that bathe mucosal surfaces, which likely aids in its ability to colonize and infect numerous sites within the human host, but also antibiotics that have been used clinically to treat infections. Recently, overexpression of the MtrC-MtrD-MtrE efflux pump was shown to be critically involved in the capacity of gonococci to develop chromosomally mediated resistance to penicillin G, which for over 40 years was used to treat gonococcal infections. Mutations in either the promoter or the coding sequence of the mtrR gene, which encodes a repressor of the efflux pump operon, decrease gonococcal susceptibility to penicillin. We now describe the capacity of MtrR to directly or indirectly influence the expression of two other loci that are involved in gonococcal susceptibility to penicillin: ponA, which encodes penicillin-binding protein 1 (PBP 1), and the pilMNOPQ operon, which encodes components of the type IV pilus secretion system, with PilQ acting as a channel for entry for penicillin. We determined that MtrR increases the expression of ponA directly or indirectly, resulting in increased levels of PBP 1, while repressing the expression of the divergently transcribed pilM gene, the first gene in the pilMNOPQ operon. Taken together with other studies, the results presented herein indicate that transcriptional regulation of gonococcal genes by MtrR is centrally involved in determining levels of gonococcal susceptibility to penicillin and provides a framework for understanding how resistance developed over the years.
Collapse
Affiliation(s)
- Jason P Folster
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | | | | |
Collapse
|
36
|
Monedero V, Mazé A, Boël G, Zúñiga M, Beaufils S, Hartke A, Deutscher J. The Phosphotransferase System of Lactobacillus casei: Regulation of Carbon Metabolism and Connection to Cold Shock Response. J Mol Microbiol Biotechnol 2006; 12:20-32. [PMID: 17183208 DOI: 10.1159/000096456] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Genome sequencing of two different Lactobacillus casei strains (ATCC334 and BL23) is presently going on and preliminary data revealed that this lactic acid bacterium possesses numerous carbohydrate transport systems probably reflecting its capacity to proliferate under varying environmental conditions. Many carbohydrate transporters belong to the phosphoenolpyruvate:sugar phosphotransferase system (PTS), but all different kinds of non-PTS transporters are present as well and their substrates are known in a few cases. In L. casei regulation of carbohydrate transport and carbon metabolism is mainly achieved by PTS proteins. Carbon catabolite repression (CCR) is mediated via several mechanisms, including the major P-Ser-HPr/catabolite control protein A (CcpA)-dependent mechanism. Catabolite response elements, the target sites for the P-Ser-HPr/CcpA complex, precede numerous genes and operons. PTS regulation domain-containing antiterminators and transcription activators are also present in both L. casei strains. Their activity is usually controlled by two PTS-mediated phosphorylation reactions exerting antagonistic effects on the transcription regulators: P~EIIB-dependent phosphorylation regulates induction of the corresponding genes and P~His-HPr-mediated phosphorylation plays a role in CCR. Carbohydrate transport of L. casei is also regulated via inducer exclusion and inducer expulsion. The presence of glucose, fructose, etc. leads to inhibition of the transport or metabolism of less favorable carbon sources (inducer exclusion) or to the export of accumulated non-metabolizable carbon sources (inducer expulsion). While P-Ser-HPr is essential for inducer exclusion of maltose, it is not necessary for the expulsion of accumulated thio-methyl-beta-D-galactopyranoside. Surprisingly, recent evidence suggests that the PTS of L. casei also plays a role in cold shock response.
Collapse
Affiliation(s)
- Vicente Monedero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Burjassot, Spain
| | | | | | | | | | | | | |
Collapse
|