1
|
Qiu Q, Li H, Sun X, Zhang L, Tian K, Chang M, Li S, Zhou D, Huo H. Study on the estradiol degradation gene expression and resistance mechanism of Rhodococcus R-001 under low-temperature stress. CHEMOSPHERE 2024; 358:142146. [PMID: 38677604 DOI: 10.1016/j.chemosphere.2024.142146] [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: 04/10/2023] [Revised: 04/03/2024] [Accepted: 04/24/2024] [Indexed: 04/29/2024]
Abstract
Estradiol (E2), an endocrine disruptor, acts by mimicking or interfering with the normal physiological functions of natural hormones within organisms, leading to issues such as endocrine system disruption. Notably, seasonal fluctuations in environmental temperature may influence the degradation speed of estradiol (E2) in the natural environment, intensifying its potential health and ecological risks. Therefore, this study aims to explore how bacteria can degrade E2 under low-temperature conditions, unveiling their resistance mechanisms, with the goal of developing new strategies to mitigate the threat of E2 to health and ecological safety. In this paper, we found that Rhodococcus equi DSSKP-R-001 (R-001) can efficiently degrade E2 at 30 °C and 10 °C. Six genes in R-001 were shown to be involved in E2 degradation by heterologous expression at 30 °C. Among them, 17β-HSD, KstD2, and KstD3, were also involved in E2 degradation at 10 °C; KstD was not previously known to degrade E2. RNA-seq was used to characterize differentially expressed genes (DEGs) to explore the stress response of R-001 to low-temperature environments to elucidate the strain's adaptation mechanism. At the low temperature, R-001 cells changed from a round spherical shape to a long rod or irregular shape with elevated unsaturated fatty acids and were consistent with the corresponding genetic changes. Many differentially expressed genes linked to the cold stress response were observed. R-001 was found to upregulate genes encoding cold shock proteins, fatty acid metabolism proteins, the ABC transport system, DNA damage repair, energy metabolism and transcriptional regulators. In this study, we demonstrated six E2 degradation genes in R-001 and found for the first time that E2 degradation genes have different expression characteristics at 30 °C and 10 °C. Linking R-001 to cold acclimation provides new insights and a mechanistic basis for the simultaneous degradation of E2 under cold stress in Rhodococcus adaptation.
Collapse
Affiliation(s)
- Qing Qiu
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Han Li
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Xuejian Sun
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Lili Zhang
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Kejian Tian
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Menghan Chang
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Shuaiguo Li
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China.
| | - Dandan Zhou
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China; Engineering Research Center of Low-Carbon Treatment and Green Development of Polluted Water in Northeast China, Ministry of Education, Northeast Normal University, Changchun, 130117, China.
| | - Hongliang Huo
- School of Environment, Northeast Normal University, No. 2555 Jingyue Avenue, Changchun City, Jilin Province, China; Engineering Research Center of Low-Carbon Treatment and Green Development of Polluted Water in Northeast China, Ministry of Education, Northeast Normal University, Changchun, 130117, China.
| |
Collapse
|
2
|
Zhang R, Wang Y. EvgS/EvgA, the unorthodox two-component system regulating bacterial multiple resistance. Appl Environ Microbiol 2023; 89:e0157723. [PMID: 38019025 PMCID: PMC10734491 DOI: 10.1128/aem.01577-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023] Open
Abstract
IMPORTANCE EvgS/EvgA, one of the five unorthodox two-component systems in Escherichia coli, plays an essential role in adjusting bacterial behaviors to adapt to the changing environment. Multiple resistance regulated by EvgS/EvgA endows bacteria to survive in adverse conditions such as acidic pH, multidrug, and heat. In this minireview, we summarize the specific structures and regulation mechanisms of EvgS/EvgA and its multiple resistance. By discussing several unresolved issues and proposing our speculations, this review will be helpful and enlightening for future directions about EvgS/EvgA.
Collapse
Affiliation(s)
- Ruizhen Zhang
- MoE Key Laboratory of Evolution and Marine Biodiversity, College of Marine Life Sciences, Ocean University of China, Qingdao, China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Yan Wang
- MoE Key Laboratory of Evolution and Marine Biodiversity, College of Marine Life Sciences, Ocean University of China, Qingdao, China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| |
Collapse
|
3
|
Zhang C, Liu M, Wu Y, Li X, Zhang C, Call DR, Liu M, Zhao Z. ArcB orchestrates the quorum-sensing system to regulate type III secretion system 1 in Vibrio parahaemolyticus. Gut Microbes 2023; 15:2281016. [PMID: 37982663 PMCID: PMC10841015 DOI: 10.1080/19490976.2023.2281016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/05/2023] [Indexed: 11/21/2023] Open
Abstract
In many Vibrio species, virulence is regulated by quorum sensing, which is regulated by a complex, multichannel, two-component phosphorelay circuit. Through this circuit, sensor kinases transmit sensory information to the phosphotransferase LuxU via a phosphotransfer mechanism, which in turn transmits the signal to the response regulator LuxO. For Vibrio parahaemolyticus, type III secretion system 1 (T3SS1) is required for cytotoxicity, but it is unclear how quorum sensing regulates T3SS1 expression. Herein, we report that a hybrid histidine kinase, ArcB, instead of LuxU, and sensor kinase LuxQ and response regulator LuxO, collectively orchestrate T3SS1 expression in V. parahaemolyticus. Under high oxygen conditions, LuxQ can interact with ArcB directly and phosphorylates the Hpt domain of ArcB. The Hpt domain of ArcB phosphorylates the downstream response regulator LuxO instead of ArcA. LuxO then activates transcription of the T3SS1 gene cluster. Under hypoxic conditions, ArcB autophosphorylates and phosphorylates ArcA, whereas ArcA does not participate in regulating the expression of T3SS1. Our data provides evidence of an alternative regulatory path involving the quorum sensing phosphorelay and adds another layer of understanding about the environmental regulation of gene expression in V. parahaemolyticus.
Collapse
Affiliation(s)
- Ce Zhang
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Min Liu
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Ying Wu
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Xixi Li
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Chen Zhang
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Douglas R. Call
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA, USA
| | - Ming Liu
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, National Clinical Research Center for Infectious Diseases, Shenzhen, Guangdong Province, China
| | - Zhe Zhao
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, China
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| |
Collapse
|
4
|
Cho LH, Yoon J, Tun W, Baek G, Peng X, Hong WJ, Mori IC, Hojo Y, Matsuura T, Kim SR, Kim ST, Kwon SW, Jung KH, Jeon JS, An G. Cytokinin increases vegetative growth period by suppressing florigen expression in rice and maize. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 110:1619-1635. [PMID: 35388561 DOI: 10.1111/tpj.15760] [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: 01/28/2022] [Revised: 03/17/2022] [Accepted: 03/28/2022] [Indexed: 05/12/2023]
Abstract
Increasing the vegetative growth period of crops can increase biomass and grain yield. In rice (Oryza sativa), the concentration of trans -zeatin, an active cytokinin, was high in the leaves during vegetative growth and decreased rapidly upon induction of florigen expression, suggesting that this hormone is involved in the regulation of the vegetative phase. To elucidate whether exogenous cytokinin application influences the length of the vegetative phase, we applied 6-benzylaminopurine (BAP) to rice plants at various developmental stages. Our treatment delayed flowering time by 8-9 days when compared with mock-treated rice plants, but only at the transition stage when the flowering signals were produced. Our observations also showed that flowering in the paddy field is delayed by thidiazuron, a stable chemical that mimics the effects of cytokinin. The transcript levels of florigen genes Heading date 3a (Hd3a) and Rice Flowering locus T1 (RFT1) were significantly reduced by the treatment, but the expression of Early heading date 1 (Ehd1), a gene found directly upstream of the florigen genes, was not altered. In maize (Zea mays), similarly, BAP treatment increased the vegetative phage by inhibiting the expression of ZCN8, an ortholog of Hd3a. We showed that cytokinin treatment induced the expression of two type-A response regulators (OsRR1 and OsRR2) which interacted with Ehd1, a type-B response regulator. We also observed that cytokinin did not affect flowering time in ehd1 knockout mutants. Our study indicates that cytokinin application increases the duration of the vegetative phase by delaying the expression of florigen genes in rice and maize by inhibiting Ehd1.
Collapse
Affiliation(s)
- Lae-Hyeon Cho
- Department of Plant Bioscience, Life and Industry Convergence Research Institute, Pusan National University, Miryang, 50463, Republic of Korea
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| | - Jinmi Yoon
- Department of Plant Bioscience, Life and Industry Convergence Research Institute, Pusan National University, Miryang, 50463, Republic of Korea
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| | - Win Tun
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| | - Gibeom Baek
- Department of Plant Bioscience, Life and Industry Convergence Research Institute, Pusan National University, Miryang, 50463, Republic of Korea
| | - Xin Peng
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
- Institute of Genomics and Bioinformatics, South China Agricultural University, Guangzhou, 510642, China
| | - Woo-Jong Hong
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| | - Izumi C Mori
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Yuko Hojo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Takakazu Matsuura
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Sung-Ryul Kim
- Novel Gene Resources Laboratory, Strategic Innovation Platform, International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines
| | - Sun-Tae Kim
- Department of Plant Bioscience, Life and Industry Convergence Research Institute, Pusan National University, Miryang, 50463, Republic of Korea
| | - Soon-Wook Kwon
- Department of Plant Bioscience, Life and Industry Convergence Research Institute, Pusan National University, Miryang, 50463, Republic of Korea
| | - Ki-Hong Jung
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| | - Jong-Seong Jeon
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| | - Gynheung An
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, South Korea
| |
Collapse
|
5
|
Yang H, Zheng Z, Zhou H, Qu H, Gao H. Proteomics Reveals the Mechanism Underlying the Autolysis of Postharvest Coprinus comatus Fruiting Bodies. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:1346-1357. [PMID: 35076245 DOI: 10.1021/acs.jafc.1c07007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Autolysis occurs widely in edible mushroom fruiting bodies after harvest, but the mechanism is still unclear. In this study, quantitative proteomics and bioinformatics analyses have been applied for revealing the autolysis mechanism of postharvest Coprinus comatus fruiting bodies. The results indicated that the autolysis mechanism of postharvest C. comatus was complicated. Before pileus opening, the carbohydrate metabolism including cell wall hydrolysis and energy biosynthesis, which were probably regulated by the ribosome, was involved in mushroom autolysis, whereas after pileus opening, the autolysis mechanism was related to the accumulated reactive oxygen species (ROS) and activated mitogen-activated protein kinase (MAPK) signaling pathway based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Furthermore, the changes in cell wall components and hydrolases, along with the production of ROS and the activities of oxidoreductase in C. comatus, were also verified to confirm the proteomic analysis results.
Collapse
Affiliation(s)
- Hailong Yang
- School of Life & Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Zhihan Zheng
- School of Life & Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Huabin Zhou
- School of Life & Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Hang Qu
- School of Life & Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Haiyan Gao
- Institute of Food Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| |
Collapse
|
6
|
Liao B, Ye X, Chen X, Zhou Y, Cheng L, Zhou X, Ren B. The two-component signal transduction system and its regulation in Candida albicans. Virulence 2021; 12:1884-1899. [PMID: 34233595 PMCID: PMC8274445 DOI: 10.1080/21505594.2021.1949883] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/13/2021] [Accepted: 06/18/2021] [Indexed: 02/08/2023] Open
Abstract
Candida albicans, which can cause superficial and life-threatening systemic infections, is the most common opportunistic fungal pathogen in the human microbiome. The two-component system is one of the most important C. albicans signal transduction pathways, regulating the response to oxidative and osmotic stresses, adhesion, morphogenesis, cell wall synthesis, virulence, drug resistance, and the host-pathogen interactions. Notably, some components of this signaling pathway have not been found in the human genome, indicating that the two-component system of C. albicans can be a potential target for new antifungal agents. Here, we summarize the composition, signal transduction, and regulation of the two-component system of C. albicans to emphasize its essential roles in the pathogenesis of C. albicans and the new therapeutic target for antifungal drugs.
Collapse
Affiliation(s)
- Biaoyou Liao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
| | - Xingchen Ye
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
| | - Xi Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yujie Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lei Cheng
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Biao Ren
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
| |
Collapse
|
7
|
Patel V, Matange N. Adaptation and compensation in a bacterial gene regulatory network evolving under antibiotic selection. eLife 2021; 10:70931. [PMID: 34591012 PMCID: PMC8483737 DOI: 10.7554/elife.70931] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/22/2021] [Indexed: 12/28/2022] Open
Abstract
Gene regulatory networks allow organisms to generate coordinated responses to environmental challenges. In bacteria, regulatory networks are re-wired and re-purposed during evolution, though the relationship between selection pressures and evolutionary change is poorly understood. In this study, we discover that the early evolutionary response of Escherichia coli to the antibiotic trimethoprim involves derepression of PhoPQ signaling, an Mg2+-sensitive two-component system, by inactivation of the MgrB feedback-regulatory protein. We report that derepression of PhoPQ confers trimethoprim-tolerance to E. coli by hitherto unrecognized transcriptional upregulation of dihydrofolate reductase (DHFR), target of trimethoprim. As a result, mutations in mgrB precede and facilitate the evolution of drug resistance. Using laboratory evolution, genome sequencing, and mutation re-construction, we show that populations of E. coli challenged with trimethoprim are faced with the evolutionary ‘choice’ of transitioning from tolerant to resistant by mutations in DHFR, or compensating for the fitness costs of PhoPQ derepression by inactivating the RpoS sigma factor, itself a PhoPQ-target. Outcomes at this evolutionary branch-point are determined by the strength of antibiotic selection, such that high pressures favor resistance, while low pressures favor cost compensation. Our results relate evolutionary changes in bacterial gene regulatory networks to strength of selection and provide mechanistic evidence to substantiate this link.
Collapse
Affiliation(s)
- Vishwa Patel
- Dr. Vikram Sarabhai Institute of Cell and Molecular Biology, The Maharaja Sayajirao University of Baroda, Vadodara, India.,Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Nishad Matange
- Indian Institute of Science Education and Research (IISER), Pune, India
| |
Collapse
|
8
|
Liu W, Li X, Qi H, Wu Y, Qu J, Yin Z, Gao X, Han A, Shuai J. Biphasic regulation of transcriptional surge generated by the gene feedback loop in a two-component system. Bioinformatics 2021; 37:2682-2690. [PMID: 33677505 DOI: 10.1093/bioinformatics/btab138] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/28/2021] [Accepted: 02/26/2021] [Indexed: 11/12/2022] Open
Abstract
MOTIVATION Transcriptional surges generated by two-component systems (TCSs) have been observed experimentally in various bacteria. Suppression of the transcriptional surge may reduce the activity, virulence, and drug resistance of bacteria. In order to investigate the general mechanisms, we use a PhoP/PhoQ TCS as a model system to derive a comprehensive mathematical modeling that governs the surge. PhoP is a response regulator, which serves as a transcription factor under a phosphorylation-dependent modulation by PhoQ, a histidine kinase. RESULTS Our model reveals two major signaling pathways to modulate the phosphorylated PhoP (P-PhoP) level, one of which promotes the generation of P-PhoP, while the other depresses the level of P-PhoP. The competition between the P-PhoP-promoting and the P-PhoP-depressing pathways determines the generation of the P-PhoP surge. Furthermore, besides PhoQ, PhoP is also a bifunctional modulator that contributes to the dynamic control of P-PhoP state, leading to a biphasic regulation of the surge by the gene feedback loop. In summary, the mechanisms derived from the PhoP/PhoQ system for the transcriptional surges provide a better understanding on such a sophisticated signal transduction system and aid to develop new antimicrobial strategies targeting TCSs. AVAILABILITY https://github.com/jianweishuai/TCS. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Wen Liu
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China
| | - Xiang Li
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China.,State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen 361102, China
| | - Hong Qi
- Complex Systems Research Center, Shanxi University, Taiyuan 030006, China
| | - Yuning Wu
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China
| | - Jing Qu
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China
| | - Zhiyong Yin
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China
| | - Xuejuan Gao
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China
| | - Aidong Han
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen 361102, China.,School of Life Sciences, Xiamen University, Xiangan, Xiamen 361102, China
| | - Jianwei Shuai
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, China.,State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen 361102, China.,National Institute for Data Science in Health and Medicine, Xiamen University, Xiamen 361102, China
| |
Collapse
|
9
|
Regulation of Streptomyces Chitinases by Two-Component Signal Transduction Systems and their Post Translational Modifications: A Review. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2018. [DOI: 10.22207/jpam.12.3.45] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
|
10
|
Shah R, Del Vecchio D. Signaling Architectures that Transmit Unidirectional Information Despite Retroactivity. Biophys J 2017; 113:728-742. [PMID: 28793226 PMCID: PMC5549655 DOI: 10.1016/j.bpj.2017.06.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/23/2017] [Accepted: 06/06/2017] [Indexed: 01/15/2023] Open
Abstract
A signaling pathway transmits information from an upstream system to downstream systems, ideally in a unidirectional fashion. A key obstacle to unidirectional transmission is retroactivity, the additional reaction flux that affects a system once its species interact with those of downstream systems. This raises the fundamental question of whether signaling pathways have developed specialized architectures that overcome retroactivity and transmit unidirectional signals. Here, we propose a general procedure based on mathematical analysis that provides an answer to this question. Using this procedure, we analyze the ability of a variety of signaling architectures to transmit one-way (from upstream to downstream) signals, as key biological parameters are tuned. We find that single stage phosphorylation and phosphotransfer systems that transmit signals from a kinase show a stringent design tradeoff that hampers their ability to overcome retroactivity. Interestingly, cascades of these architectures, which are highly represented in nature, can overcome this tradeoff and thus enable unidirectional transmission. By contrast, phosphotransfer systems, and single and double phosphorylation cycles that transmit signals from a substrate, are unable to mitigate retroactivity effects, even when cascaded, and hence are not well suited for unidirectional information transmission. These results are largely independent of the specific reaction-rate constant values, and depend on the topology of the architectures. Our results therefore identify signaling architectures that, allowing unidirectional transmission of signals, embody modular processes that conserve their input/output behavior across multiple contexts. These findings can be used to decompose natural signal transduction networks into modules, and at the same time, they establish a library of devices that can be used in synthetic biology to facilitate modular circuit design.
Collapse
Affiliation(s)
- Rushina Shah
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
| | - Domitilla Del Vecchio
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| |
Collapse
|
11
|
Utsumi R. Bacterial signal transduction networks via connectors and development of the inhibitors as alternative antibiotics. Biosci Biotechnol Biochem 2017; 81:1663-1669. [PMID: 28743208 DOI: 10.1080/09168451.2017.1350565] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bacterial cells possess a signal transduction system that differs from those described in higher organisms, including human cells. These so-called two-component signal transduction systems (TCSs) consist of a sensor (histidine kinase, HK) and a response regulator, and are involved in cellular functions, such as virulence, drug resistance, biofilm formation, cell wall synthesis, cell division. They are conserved in bacteria across all species. Although TCSs are often studied and characterized individually, they are assumed to interact with each other and form signal transduction networks within the cell. In this review, I focus on the formation of TCS networks via connectors. I also explore the possibility of using TCS inhibitors, especially HK inhibitors, as alternative antimicrobial agents.
Collapse
Affiliation(s)
- Ryutaro Utsumi
- a Department of Bioscience, Graduate School of Agriculture , Kindai University , Nara , Japan
| |
Collapse
|
12
|
Page SC, Silversmith RE, Collins EJ, Bourret RB. Imidazole as a Small Molecule Analogue in Two-Component Signal Transduction. Biochemistry 2015; 54:7248-60. [PMID: 26569142 DOI: 10.1021/acs.biochem.5b01082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In two-component signal transduction systems (TCSs), responses to stimuli are mediated through phosphotransfer between protein components. Canonical TCSs use His → Asp phosphotransfer in which phosphoryl groups are transferred from a conserved His on a sensory histidine kinase (HK) to a conserved Asp on a response regulator (RR). RRs contain the catalytic core of His → Asp phosphotransfer, evidenced by the ability of RRs to autophosphorylate with small molecule analogues of phospho-His proteins. Phosphorelays are a more complex variation of TCSs that additionally utilize Asp → His phosphotransfer through the use of an additional component, the histidine-containing phosphotransfer domain (Hpt), which reacts with RRs both as phosphodonors and phosphoacceptors. Here we show that imidazole has features of a rudimentary Hpt. Imidazole acted as a nucleophile and attacked phosphorylated RRs (RR-P) to produce monophosphoimidazole (MPI) and unphosphorylated RR. Phosphotransfer from RR-P to imidazole required the intact RR active site, indicating that the RR provided the core catalytic machinery for Asp → His phosphotransfer. Imidazole functioned in an artificial phosphorelay to transfer phosphoryl groups between unrelated RRs. The X-ray crystal structure of an activated RR·imidazole complex showed imidazole oriented in the RR active site similarly to the His of an Hpt. Imidazole interacted with RR nonconserved active site residues, which influenced the relative reactivity of RR-P with imidazole versus water. Rate constants for reaction of imidazole or MPI with chimeric RRs suggested that the RR active site contributes to the kinetic preferences exhibited by the YPD1 Hpt.
Collapse
Affiliation(s)
- Stephani C Page
- Department of Biochemistry & Biophysics, University of North Carolina , Chapel Hill, North Carolina 27599-7260, United States
| | - Ruth E Silversmith
- Department of Microbiology & Immunology, University of North Carolina , Chapel Hill, North Carolina 27599-7290, United States
| | - Edward J Collins
- Department of Biochemistry & Biophysics, University of North Carolina , Chapel Hill, North Carolina 27599-7260, United States.,Department of Microbiology & Immunology, University of North Carolina , Chapel Hill, North Carolina 27599-7290, United States
| | - Robert B Bourret
- Department of Microbiology & Immunology, University of North Carolina , Chapel Hill, North Carolina 27599-7290, United States
| |
Collapse
|
13
|
Nguyen MP, Yoon JM, Cho MH, Lee SW. Prokaryotic 2-component systems and the OmpR/PhoB superfamily. Can J Microbiol 2015; 61:799-810. [DOI: 10.1139/cjm-2015-0345] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In bacteria, 2-component regulatory systems (TCSs) are the critical information-processing pathways that link stimuli to specific adaptive responses. Signals perceived by membrane sensors, which are generally histidine kinases, are transmitted by response regulators (RRs) to allow cells to cope rapidly and effectively with environmental challenges. Over the past few decades, genes encoding components of TCSs and their responsive proteins have been identified, crystal structures have been described, and signaling mechanisms have been elucidated. Here, we review recent findings and interesting breakthroughs in bacterial TCS research. Furthermore, we discuss structural features, mechanisms of activation and regulation, and cross-regulation of RRs, with a focus on the largest RR family, OmpR/PhoB, to provide a comprehensive overview of these critically important signaling molecules.
Collapse
Affiliation(s)
| | - Joo-Mi Yoon
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
| | - Man-Ho Cho
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
| | - Sang-Won Lee
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
| |
Collapse
|
14
|
Oxygen-Dependent Cell-to-Cell Variability in the Output of the Escherichia coli Tor Phosphorelay. J Bacteriol 2015; 197:1976-87. [PMID: 25825431 DOI: 10.1128/jb.00074-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 03/23/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Escherichia coli senses and responds to trimethylamine-N-oxide (TMAO) in the environment through the TorT-TorS-TorR signal transduction system. The periplasmic protein TorT binds TMAO and stimulates the hybrid kinase TorS to phosphorylate the response regulator TorR through a phosphorelay. Phosphorylated TorR, in turn, activates transcription of the torCAD operon, which encodes the proteins required for anaerobic respiration via reduction of TMAO to trimethylamine. Interestingly, E. coli respires TMAO in both the presence and absence of oxygen, a behavior that is markedly different from the utilization of other alternative electron acceptors by this bacterium. Here we describe an unusual form of regulation by oxygen for this system. While the average level of torCAD transcription is the same for aerobic and anaerobic cultures containing TMAO, the behavior across the population of cells is strikingly different under the two growth conditions. Cellular levels of torCAD transcription in aerobic cultures are highly heterogeneous, in contrast to the relatively homogeneous distribution in anaerobic cultures. Thus, oxygen regulates the variance of the output but not the mean for the Tor system. We further show that this oxygen-dependent variability stems from the phosphorelay. IMPORTANCE Trimethylamine-N-oxide (TMAO) is utilized by numerous bacteria as an electron acceptor for anaerobic respiration. In E. coli, expression of the proteins required for TMAO respiration is tightly regulated by a signal transduction system that is activated by TMAO. Curiously, although oxygen is the energetically preferred electron acceptor, TMAO is respired even in the presence of oxygen. Here we describe an interesting and unexpected form of regulation for this system in which oxygen produces highly variable expression of the TMAO utilization proteins across a population of cells without affecting the mean expression of these proteins. To our knowledge, this is the first reported example of a stimulus regulating the variance but not the mean output of a signaling system.
Collapse
|
15
|
A load driver device for engineering modularity in biological networks. Nat Biotechnol 2014; 32:1268-75. [PMID: 25419739 PMCID: PMC4262674 DOI: 10.1038/nbt.3044] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 09/03/2014] [Indexed: 11/21/2022]
Abstract
The behavior of gene modules in complex synthetic circuits is often unpredictable1–4. Upon joining modules to create a circuit, downstream elements (such as binding sites for a regulatory protein) apply a load to upstream modules that can negatively affect circuit function1,5. Here we devise a genetic device named a load driver that mitigates the impact of load on circuit function, and we demonstrate its behavior in Saccharomyces cerevisiae. The load driver implements the design principle of time scale separation: inclusion of the load driver’s fast phosphotransfer processes restores the capability of a slower transcriptional circuit to respond to time-varying input signals even in the presence of substantial load. Without the load driver, we observe circuit behavior that suffers from 76% delay in response time and a 25% decrease in system bandwidth due to load. With the addition of a load driver, circuit performance is almost completely restored. Load drivers will serve as fundamental building blocks in the creation of complex, higher level genetic circuits.
Collapse
|
16
|
Molecular Mechanism of Transcriptional Cascade Initiated by the EvgS/EvgA System inEscherichia coliK-12. Biosci Biotechnol Biochem 2014; 73:870-8. [DOI: 10.1271/bbb.80795] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
17
|
Straube R. Reciprocal regulation as a source of ultrasensitivity in two-component systems with a bifunctional sensor kinase. PLoS Comput Biol 2014; 10:e1003614. [PMID: 24809699 PMCID: PMC4014401 DOI: 10.1371/journal.pcbi.1003614] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/24/2014] [Indexed: 01/31/2023] Open
Abstract
Two-component signal transduction systems, where the phosphorylation state of a regulator protein is modulated by a sensor kinase, are common in bacteria and other microbes. In many of these systems, the sensor kinase is bifunctional catalyzing both, the phosphorylation and the dephosphorylation of the regulator protein in response to input signals. Previous studies have shown that systems with a bifunctional enzyme can adjust the phosphorylation level of the regulator protein independently of the total protein concentrations – a property known as concentration robustness. Here, I argue that two-component systems with a bifunctional enzyme may also exhibit ultrasensitivity if the input signal reciprocally affects multiple activities of the sensor kinase. To this end, I consider the case where an allosteric effector inhibits autophosphorylation and, concomitantly, activates the enzyme's phosphatase activity, as observed experimentally in the PhoQ/PhoP and NRII/NRI systems. A theoretical analysis reveals two operating regimes under steady state conditions depending on the effector affinity: If the affinity is low the system produces a graded response with respect to input signals and exhibits stimulus-dependent concentration robustness – consistent with previous experiments. In contrast, a high-affinity effector may generate ultrasensitivity by a similar mechanism as phosphorylation-dephosphorylation cycles with distinct converter enzymes. The occurrence of ultrasensitivity requires saturation of the sensor kinase's phosphatase activity, but is restricted to low effector concentrations, which suggests that this mode of operation might be employed for the detection and amplification of low abundant input signals. Interestingly, the same mechanism also applies to covalent modification cycles with a bifunctional converter enzyme, which suggests that reciprocal regulation, as a mechanism to generate ultrasensitivity, is not restricted to two-component systems, but may apply more generally to bifunctional enzyme systems. Bacteria often use two-component systems to sense and respond to environmental changes, which involves autophosphorylation of a sensor kinase and phosphotransfer to a cognate response regulator. However, despite conservation of this ‘classical’ scheme there exist substantial variations in the mechanism of phosphotransfer among systems. Also, many sensor kinases exhibit phosphatase activity raising the question whether such a bifunctional architecture enables special regulatory properties in the response behavior to input signals. According to previous studies, classical two-component systems are unlikely to produce sigmoidal response curves (ultrasensitivity) if the sensor protein is bifunctional. Here, I argue that this is not necessarily true if the input stimulus (allosteric effector) reciprocally affects multiple activities of the sensor kinase, as it seems to be common for bifunctional enzymes. To this end, I propose and analyze an extension of the experimentally well-supported Batchelor-Goulian model which shows that ultrasensitivity requires a high-affinity effector and saturation of the phosphatase activity. The underlying mechanism involves sequestration of the effector by the sensor kinase which restricts the occurrence of ultrasensitivity to sufficiently low effector concentrations. Hence, this operating regime might be useful to sense effector limitations or to amplify weak input signals.
Collapse
Affiliation(s)
- Ronny Straube
- Analysis and Redesign of Biological Networks Group, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- * E-mail:
| |
Collapse
|
18
|
Dual-histidine kinases in basidiomycete fungi. C R Biol 2014; 337:111-6. [PMID: 24581805 DOI: 10.1016/j.crvi.2013.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/15/2013] [Accepted: 12/17/2013] [Indexed: 11/20/2022]
Abstract
Dual-histidine kinases (HKs) are complex hybrid HKs containing in a single polypeptide two HK transmitter modules (T) and two-response regulator received domains (R) that are combined in a TRTR geometry. In fungi, this protein family is limited to some particular species of the phylum Basidiomycota and absent in the other phyla. This study extends the investigation of dual-HKs to 80 fully sequenced genomes of basidiomycetes, analyzing their distribution, domain architecture and phylogenetic relationships. Moreover, similarly to dual-HKs of basidiomycetes, several species of bacteria were found that contain hybrid HKs with a TRTR domain architecture encoded in a single gene.
Collapse
|
19
|
Abstract
Cytokinins are N (6) substituted adenine derivatives that affect many aspects of plant growth and development, including cell division, shoot initiation and growth, leaf senescence, apical dominance, sink/source relationships, nutrient uptake, phyllotaxis, and vascular, gametophyte, and embryonic development, as well as the response to biotic and abiotic factors. Molecular genetic studies in Arabidopsis have helped elucidate the mechanisms underlying the function of this phytohormone in plants. Here, we review our current understanding of cytokinin biosynthesis and signaling in Arabidopsis, the latter of which is similar to bacterial two-component phosphorelays. We discuss the perception of cytokinin by the ER-localized histidine kinase receptors, the role of the AHPs in mediating the transfer of the phosphoryl group from the receptors to the response regulators (ARRs), and finally the role of the large ARR family in cytokinin function. The identification and genetic manipulation of the genes involved in cytokinin metabolism and signaling have helped illuminate the roles of cytokinins in Arabidopsis. We discuss these diverse roles, and how other signaling pathways influence cytokinin levels and sensitivity though modulation of the expression of cytokinin signaling and metabolic genes.
Collapse
Affiliation(s)
- Joseph J Kieber
- University of North Carolina, Biology Department, Chapel Hill, NC 27599-3280
| | - G Eric Schaller
- Dartmouth College, Department of Biological Sciences, Hanover, NH 03755
| |
Collapse
|
20
|
Luo SC, Lou YC, Rajasekaran M, Chang YW, Hsiao CD, Chen C. Structural basis of a physical blockage mechanism for the interaction of response regulator PmrA with connector protein PmrD from Klebsiella pneumoniae. J Biol Chem 2013; 288:25551-25561. [PMID: 23861396 PMCID: PMC3757216 DOI: 10.1074/jbc.m113.481978] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In bacteria, the two-component system is the most prevalent for sensing and transducing environmental signals into the cell. The PmrA-PmrB two-component system, responsible for sensing external stimuli of high Fe(3+) and mild acidic conditions, can control the genes involved in lipopolysaccharide modification and polymyxin resistance in pathogens. In Klebsiella pneumoniae, the small basic connector protein PmrD protects phospho-PmrA and prolongs the expression of PmrA-activated genes. We previously determined the phospho-PmrA recognition mode of PmrD. However, how PmrA interacts with PmrD and prevents its dephosphorylation remains unknown. To address this question, we solved the x-ray crystal structure of the N-terminal receiver domain of BeF3(-)-activated PmrA (PmrA(N)) at 1.70 Å. With this structure, we applied the data-driven docking method based on NMR chemical shift perturbation to generate the complex model of PmrD-PmrA(N), which was further validated by site-directed spin labeling experiments. In the complex model, PmrD may act as a blockade to prevent phosphatase from contacting with the phosphorylation site on PmrA.
Collapse
Affiliation(s)
| | | | | | - Yi-Wei Chang
- Molecular Biology, Academia Sinica, Taipei 115, Taiwan and
| | | | - Chinpan Chen
- From the Institutes of Biomedical Sciences and ,Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, To whom correspondence should be addressed: Institute of Biomedical Sciences, Academia Sinica, 128 Academia Rd., Section 2, Taipei 115, Taiwan. Tel.: 886-2-2652-3035; Fax: 886-2-2788-7641; E-mail:
| |
Collapse
|
21
|
Del Bianco M, Giustini L, Sabatini S. Spatiotemporal changes in the role of cytokinin during root development. THE NEW PHYTOLOGIST 2013; 199:324-338. [PMID: 23692218 DOI: 10.1111/nph.12338] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/12/2013] [Indexed: 05/07/2023]
Abstract
The root is a dynamic system whose structure is regulated by a complex network of interactions between hormones. The primary root meristem is specified in the embryo. After germination, the primary root meristem grows and then reaches a final size that will be maintained during the life of the plant. Subsequently, secondary structures such as lateral roots and root nodules form via the re-specification of differentiated cells. Cytokinin plays key roles in the regulation of root development. Down-regulation of the cytokinin response is required for the specification of a new stem cell niche, during both embryo and lateral root development. In the root meristem, cytokinin signalling regulates the longitudinal zonation of the meristem by controlling cell differentiation. Moreover, cytokinin regulates radial patterning of root vasculature by promoting protophloem cell identity and by spatially inhibiting protoxylem formation. In this review, an effort is made to describe the known details of the role of cytokinin during root development, taking into account also the interactions between cytokinin and other hormones. Attention is given on the dynamicity of cytokinin signalling output during different developmental events. Indeed, there is much evidence that the effects of cytokinin change as organs grow, underlining the importance of the spatiotemporal specificity of cytokinin signalling.
Collapse
Affiliation(s)
- Marta Del Bianco
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| | - Leonardo Giustini
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| | - Sabrina Sabatini
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| |
Collapse
|
22
|
SCF(KMD) controls cytokinin signaling by regulating the degradation of type-B response regulators. Proc Natl Acad Sci U S A 2013; 110:10028-33. [PMID: 23720308 DOI: 10.1073/pnas.1300403110] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytokinins are plant hormones that play critical roles in growth and development. In Arabidopsis, the transcriptional response to cytokinin is regulated by action of type-B Arabidopsis response regulators (ARRs). Although central elements in the cytokinin signal transduction pathway have been identified, mechanisms controlling output remain to be elucidated. Here we demonstrate that a family of F-box proteins, called the kiss me deadly (KMD) family, targets type-B ARR proteins for degradation. KMD proteins form an S-phase kinase-associated PROTEIN1 (SKP1)/Cullin/F-box protein (SCF) E3 ubiquitin ligase complex and directly interact with type-B ARR proteins. Loss-of-function KMD mutants stabilize type-B ARRs and exhibit an enhanced cytokinin response. In contrast, plants with elevated KMD expression destabilize type-B ARR proteins leading to cytokinin insensitivity. Our results support a model in which an SCF(KMD) complex negatively regulates cytokinin responses by controlling levels of a key family of transcription factors.
Collapse
|
23
|
Structure, function, and biology of the Enterococcus faecalis cytolysin. Toxins (Basel) 2013; 5:895-911. [PMID: 23628786 PMCID: PMC3709268 DOI: 10.3390/toxins5050895] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 04/22/2013] [Accepted: 04/23/2013] [Indexed: 11/17/2022] Open
Abstract
Enterococcus faecalis is a Gram-positive commensal member of the gut microbiota of a wide range of organisms. With the advent of antibiotic therapy, it has emerged as a multidrug resistant, hospital-acquired pathogen. Highly virulent strains of E. faecalis express a pore-forming exotoxin, called cytolysin, which lyses both bacterial and eukaryotic cells in response to quorum signals. Originally described in the 1930s, the cytolysin is a member of a large class of lanthionine-containing bacteriocins produced by Gram-positive bacteria. While the cytolysin shares some core features with other lantibiotics, it possesses unique characteristics as well. The current understanding of cytolysin biosynthesis, structure/function relationships, and contribution to the biology of E. faecalis are reviewed, and opportunities for using emerging technologies to advance this understanding are discussed.
Collapse
|
24
|
Nicotinic acid modulates Legionella pneumophila gene expression and induces virulence traits. Infect Immun 2013; 81:945-55. [PMID: 23319553 DOI: 10.1128/iai.00999-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In response to environmental fluctuations or stresses, bacteria can activate transcriptional and phenotypic programs to coordinate an adaptive response. The intracellular pathogen Legionella pneumophila converts from a noninfectious replicative form to an infectious transmissive form when the bacterium encounters alterations in either amino acid concentrations or fatty acid biosynthesis. Here, we report that L. pneumophila differentiation is also triggered by nicotinic acid, a precursor of the central metabolite NAD(+). In particular, when replicative L. pneumophila are treated with 5 mM nicotinic acid, the bacteria induce numerous transmissive-phase phenotypes, including motility, cytotoxicity toward macrophages, sodium sensitivity, and lysosome avoidance. Transcriptional profile analysis determined that nicotinic acid induces the expression of a panel of genes characteristic of transmissive-phase L. pneumophila. Moreover, an additional 213 genes specific to nicotinic acid treatment were altered. Although nearly 25% of these genes lack an assigned function, the gene most highly induced by nicotinic acid treatment encodes a putative major facilitator superfamily transporter, Lpg0273. Indeed, lpg0273 protects L. pneumophila from toxic concentrations of nicotinic acid as judged by analyzing the growth of the corresponding mutant. The broad utility of the nicotinic acid pathway to couple central metabolism and cell fate is underscored by this small metabolite's modulation of gene expression by diverse microbes, including Candida glabrata, Bordetella pertussis, Escherichia coli, and L. pneumophila.
Collapse
|
25
|
Lavín JL, García-Yoldi A, Ramírez L, Pisabarro AG, Oguiza JA. Two-component signal transduction in Agaricus bisporus: a comparative genomic analysis with other basidiomycetes through the web-based tool BASID2CS. Fungal Genet Biol 2012; 55:77-84. [PMID: 23123423 DOI: 10.1016/j.fgb.2012.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 09/28/2012] [Accepted: 09/29/2012] [Indexed: 11/16/2022]
Abstract
Two-component systems (TCSs) are signal transduction mechanisms present in many eukaryotes, including fungi that play essential roles in the regulation of several cellular functions and responses. In this study, we carry out a genomic analysis of the TCS proteins in two varieties of the white button mushroom Agaricus bisporus. The genomes of both A. bisporus varieties contain eight genes coding for TCS proteins, which include four hybrid Histidine Kinases (HKs), a single histidine-containing phosphotransfer (HPt) protein and three Response Regulators (RRs). Comparison of the TCS proteins among A. bisporus and the sequenced basidiomycetes showed a conserved core complement of five TCS proteins including the Tco1/Nik1 hybrid HK, HPt protein and Ssk1, Skn7 and Rim15-like RRs. In addition, Dual-HKs, unusual hybrid HKs with 2 HK and 2 RR domains, are absent in A. bisporus and are limited to various species of basidiomycetes. Differential expression analysis showed no significant up- or down-regulation of the Agaricus TCS genes in the conditions/tissue analyzed with the exception of the Skn7-like RR gene (Agabi_varbisH97_2|198669) that is significantly up-regulated on compost compared to cultured mycelia. Furthermore, the pipeline web server BASID2CS (http://bioinformatics.unavarra.es:1000/B2CS/BASID2CS.htm) has been specifically designed for the identification, classification and functional annotation of putative TCS proteins from any predicted proteome of basidiomycetes using a combination of several bioinformatic approaches.
Collapse
Affiliation(s)
- José L Lavín
- Genetics and Microbiology Research Group, Departamento de Producción Agraria, Universidad Pública de Navarra, 31006 Pamplona, Spain
| | | | | | | | | |
Collapse
|
26
|
Bhardwaj D, Lakhanpaul S, Tuteja N. Wide range of interacting partners of pea Gβ subunit of G-proteins suggests its multiple functions in cell signalling. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2012; 58:1-5. [PMID: 22750791 DOI: 10.1016/j.plaphy.2012.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/05/2012] [Indexed: 06/01/2023]
Abstract
Climate change is a major concern especially in view of the increasing global population and food security. Plant scientists need to look for genetic tools whose appropriate usage can contribute to sustainable food availability. G-proteins have been identified as some of the potential genetic tools that could be useful for protecting plants from various stresses. Heterotrimeric G-proteins consisting of three subunits Gα, Gβ and Gγ are important components of a number of signalling pathways. Their structure and functions are already well studied in animals but their potential in plants is now gaining attention for their role in stress tolerance. Earlier we have reported that over expressing pea Gβ conferred heat tolerance in tobacco plants. Here we report the interacting partners (proteins) of Gβ subunit of Pisum sativum and their putative role in stress and development. Out of 90 transformants isolated from the yeast-two-hybrid (Y2H) screening, seven were chosen for further investigation due to their recurrence in multiple experiments. These interacting partners were confirmed using β-galactosidase colony filter lift and ONPG (O-nitrophenyl-β-D-galactopyranoside) assays. These partners include thioredoxin H, histidine-containing phosphotransfer protein 5-like, pathogenesis-related protein, glucan endo-beta-1, 3-glucosidase (acidic isoform), glycine rich RNA binding protein, cold and drought-regulated protein (corA gene) and soluble inorganic pyrophosphatase 1. This study suggests the role of pea Gβ subunit in stress signal transduction and development pathways owing to its capability to interact with a wide range of proteins of multiple functions.
Collapse
|
27
|
Mirabella A, Yañez Villanueva RM, Delrue RM, Uzureau S, Zygmunt MS, Cloeckaert A, De Bolle X, Letesson JJ. The two-component system PrlS/PrlR of Brucella melitensis is required for persistence in mice and appears to respond to ionic strength. MICROBIOLOGY-SGM 2012; 158:2642-2651. [PMID: 22859617 DOI: 10.1099/mic.0.060863-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacterial adaptation to environmental conditions is essential to ensure maximal fitness in the face of several stresses. In this context, two-component systems (TCSs) represent a predominant signal transduction mechanism, allowing an appropriate response to be mounted when a stimulus is sensed. As facultative intracellular pathogens, Brucella spp. face various environmental conditions, and an adequate response is required for a successful infection process. Recently, bioinformatic analysis of Brucella genomes predicted a set of 15 bona fide TCS pairs, among which some have been previously investigated. In this report, we characterized a new TCS locus called prlS/R, for probable proline sensor-regulator. It encodes a hybrid histidine kinase (PrlS) with an unusual Na(+)/solute symporter N-terminal domain and a transcriptional regulator (belonging to the LuxR family) (PrlR). In vitro, Brucella spp. with a functional PrlR/S system form bacterial aggregates, which seems to be an adaptive response to a hypersaline environment, while a prlS/R mutant does not. We identified ionic strength as a possible signal sensed by this TCS. Finally, this work correlates the absence of a functional PrlR/S system with the lack of hypersaline-induced aggregation in particular marine Brucella spp.
Collapse
Affiliation(s)
- Aurélie Mirabella
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Rosse-Mary Yañez Villanueva
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Rose-May Delrue
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Sophie Uzureau
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Michel S Zygmunt
- Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, F-37000 Tours, France.,INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France
| | - Axel Cloeckaert
- Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, F-37000 Tours, France.,INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France
| | - Xavier De Bolle
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Jean-Jacques Letesson
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| |
Collapse
|
28
|
Krell T, Lacal J, Guazzaroni ME, Busch A, Silva-Jiménez H, Fillet S, Reyes-Darías JA, Muñoz-Martínez F, Rico-Jiménez M, García-Fontana C, Duque E, Segura A, Ramos JL. Responses of Pseudomonas putida to toxic aromatic carbon sources. J Biotechnol 2012; 160:25-32. [DOI: 10.1016/j.jbiotec.2012.01.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 01/16/2012] [Accepted: 01/24/2012] [Indexed: 10/14/2022]
|
29
|
Exact analysis of intrinsic qualitative features of phosphorelays using mathematical models. J Theor Biol 2012; 300:7-18. [DOI: 10.1016/j.jtbi.2012.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/21/2011] [Accepted: 01/04/2012] [Indexed: 11/23/2022]
|
30
|
Silva-Jiménez H, Ramos JL, Krell T. Construction of a prototype two-component system from the phosphorelay system TodS/TodT. Protein Eng Des Sel 2012; 25:159-69. [PMID: 22308529 DOI: 10.1093/protein/gzs001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Two-component systems (TCSs) play key roles in the adaptation of bacteria to environmental changes. In prototype TCSs a single phosphoryl transfer between the sensor kinase and response regulator occurs, whereas phosphorelay TCSs are characterised by a His1-Asp1-His2-Asp2 phosphorylation cascade. The TodS/TodT TCS controls the expression of a toluene degradation pathway and the TodS sensor kinase operates by a three-step internal phosphorelay. Based on TodS we report the construction of a minimal form of TodS, termed as Min-TodS, that contains only three of the seven TodS domains. Min-TodS is composed of the N-terminal PAS sensor domain as well as the C-terminal dimerisation/phosphotransfer domain and catalytic domain of TodS. We have conducted a comparative analysis of the phosphorelay TCS with its prototypal derivative. We demonstrate that Min-TodS binds effector molecules with affinities comparable with those observed for TodS. Min-TodS forms a TCS with TodT and toluene increases the amount of TodT-P. In contrast to TodS, toluene does not stimulate Min-TodS autophosphorylation. The half-life of Min-TodS-P was significantly increased as compared with TodS. Analysis of TodSD500A revealed that the hydrolysis of the acylphosphate of the receiver domain is responsible for the reduced half-life of TodS. The regulation of P(todX) expression by Min-TodS/TodT and TodS/TodT in response to different effectors are compared. The Min-TodS/TodT system was characterized by a higher basal activity but a lower magnitude of response. Data will be discussed in the context that the phosphorelay system appears to be better suited for the control of a degradation pathway for toxic compounds.
Collapse
Affiliation(s)
- Hortencia Silva-Jiménez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008 Granada, Spain
| | | | | |
Collapse
|
31
|
Silva-Jiménez H, García-Fontana C, Cadirci BH, Ramos-González MI, Ramos JL, Krell T. Study of the TmoS/TmoT two-component system: towards the functional characterization of the family of TodS/TodT like systems. Microb Biotechnol 2011; 5:489-500. [PMID: 22212183 PMCID: PMC3815326 DOI: 10.1111/j.1751-7915.2011.00322.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The two‐component system TmoS/TmoT controls the expression of the toluene‐4‐monooxygenase pathway in Pseudomonas mendocina RK1 via modulation of PtmoX activity. The TmoS/TmoT system belongs to the family of TodS/TodT like proteins. The sensor kinase TmoS is a 108 kDa protein composed of seven different domains. Using isothermal titration calorimetry we show that purified TmoS binds a wide range of aromatic compounds with high affinities. Tightest ligand binding was observed for toluene (KD = 150 nM), which corresponds to the highest affinity measured between an effector and a sensor kinase. Other compounds with affinities in the nanomolar range include benzene, the 3 xylene isomers, styrene, nitrobenzene or p‐chlorotoluene. We demonstrate that only part of the ligands that bind to TmoS increase protein autophosphorylation in vitro and consequently pathway expression in vivo. These compounds are referred to as agonists. Other TmoS ligands, termed antagonists, failed to increase TmoS autophosphorylation, which resulted in their incapacity to stimulate gene expression in vivo. We also show that TmoS saturated with different agonists differs in their autokinase activities. The effector screening of gene expression showed that promoter activity of PtmoX and PtodX (controlled by the TodS/TodT system) is mediated by the same set of 22 compounds. The common structural feature of these compounds is the presence of a single aromatic ring. Among these ligands, toluene was the most potent inducer of both promoter activities. Information on the TmoS/TmoT and TodS/TodT system combined with a sequence analysis of family members permits to identify distinct features that define this protein family.
Collapse
Affiliation(s)
- Hortencia Silva-Jiménez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda 1, Granada, Spain.
| | | | | | | | | | | |
Collapse
|
32
|
Sun Q, Julian RR. Probing sites of histidine phosphorylation with iodination and tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:2240-2246. [PMID: 21732455 DOI: 10.1002/rcm.5116] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phosphorylation at histidine residues occurs frequently in biology, but is often overlooked in proteomics experiments due to extreme acid lability. A new method utilizing histidine labeling with iodine to record information about phosphorylation is described. Essentially, phosphorylated histidine residues are not labeled while unmodified histidine undergoes complete iodination. Iodination is stabile both under acidic conditions, and upon collisional activation in the gas phase. This enables site-specific information to be retained with standard liquid chromatography separations and tandem mass spectrometry by collisional activation. Semi-quantitative information about the relative amounts of phosphorylated versus unmodified states can also be easily obtained from the relative ion abundances. This new method should provide a pathway forward for analyzing histidine phosphorylation in complex systems.
Collapse
Affiliation(s)
- Qingyu Sun
- Department of Chemistry, University of California, Riverside, 900 University Ave, Riverside, CA 92521, USA
| | | |
Collapse
|
33
|
Parnell JJ, Callister SJ, Rompato G, Nicora CD, Paša-Tolić L, Williamson A, Pfrender ME. Time-course analysis of the Shewanella amazonensis SB2B proteome in response to sodium chloride shock. Sci Rep 2011; 1:25. [PMID: 22355544 PMCID: PMC3216512 DOI: 10.1038/srep00025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 06/16/2011] [Indexed: 12/04/2022] Open
Abstract
Shewanellae are microbial models for environmental stress response; however, the sequential expression of mechanisms in response to stress is poorly understood. Here we experimentally determine the response mechanisms of Shewanella amazonensis SB2B during sodium chloride stress using a novel liquid chromatography and accurate mass-time tag mass spectrometry time-course proteomics approach. The response of SB2B involves an orchestrated sequence of events comprising increased signal transduction associated with motility and restricted growth. Following a metabolic shift to branched chain amino acid degradation, motility and cellular replication proteins return to pre-perturbed levels. Although sodium chloride stress is associated with a change in the membrane fatty acid composition in other organisms, this is not the case for SB2B as fatty acid degradation pathways are not expressed and no change in the fatty acid profile is observed. These findings suggest that shifts in membrane composition may be an indirect physiological response to high NaCl stress.
Collapse
Affiliation(s)
- J Jacob Parnell
- Center for Integrated BioSystems and Department of Biology, Utah State University, Logan, UT, USA.
| | | | | | | | | | | | | |
Collapse
|
34
|
Jagadeesan S, Mann P, Schink CW, Higgs PI. A novel "four-component" two-component signal transduction mechanism regulates developmental progression in Myxococcus xanthus. J Biol Chem 2009; 284:21435-45. [PMID: 19535336 PMCID: PMC2755868 DOI: 10.1074/jbc.m109.033415] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Histidine-aspartate phosphorelays are employed by two-component signal transduction family proteins to mediate responses to specific signals or stimuli in microorganisms and plants. The RedCDEF proteins constitute a novel signaling system in which four two-component proteins comprising a histidine kinase, a histidine-kinase like protein, and two response regulators function together to regulate progression through the elaborate developmental program of Myxococcus xanthus. A combination of in vivo phenotypic analyses of in-frame deletions and non-functional point mutations in each gene as well as in vitro autophosphorylation and phosphotransfer analyses of recombinant proteins indicate that the RedC histidine kinase protein autophosphorylates and donates a phosphoryl group to the single domain response regulator, RedF, to repress progression through the developmental program. To relieve this developmental repression, RedC instead phosphorylates RedD, a dual receiver response regulator protein. Surprisingly, RedD transfers the phosphoryl group to the histidine kinase-like protein RedE, which itself appears to be incapable of autophosphorylation. Phosphorylation of RedE may render RedE accessible to RedF, where it removes the phosphoryl group from RedF-P, which is otherwise an unusually stable phosphoprotein. These analyses reveal a novel "four-component" signaling mechanism that has probably arisen to temporally coordinate signals controlling the developmental program in M. xanthus. The RedCDEF signaling system provides an important example of how the inherent plasticity and modularity of the basic two-component signaling domains comprise a highly adaptable framework well suited to expansion into complex signaling mechanisms.
Collapse
Affiliation(s)
- Sakthimala Jagadeesan
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | | | | | | |
Collapse
|
35
|
Lagomarsino MC, Bassetti B, Castellani G, Remondini D. Functional models for large-scale gene regulation networks: realism and fiction. MOLECULAR BIOSYSTEMS 2009; 5:335-44. [PMID: 19396369 DOI: 10.1039/b816841p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-throughput experiments are shedding light on the topology of large regulatory networks and at the same time their functional states, namely the states of activation of the nodes (for example transcript or protein levels) in different conditions, times, environments. We now possess a certain amount of information about these two levels of description, stored in libraries, databases and ontologies. A current challenge is to bridge the gap between topology and function, i.e. developing quantitative models aimed at characterizing the expression patterns of large sets of genes. However, approaches that work well for small networks become impossible to master at large scales, mainly because parameters proliferate. In this review we discuss the state of the art of large-scale functional network models, addressing the issue of what can be considered as "realistic" and what the main limitations may be. We also show some directions for future work, trying to set the goals that future models should try to achieve. Finally, we will emphasize the possible benefits in the understanding of biological mechanisms underlying complex multifactorial diseases, and in the development of novel strategies for the description and the treatment of such pathologies.
Collapse
|
36
|
Sellerio A, Bassetti B, Isambert H, Cosentino Lagomarsino M. A comparative evolutionary study of transcription networks. The global role of feedback and hierachical structures. ACTA ACUST UNITED AC 2009; 5:170-9. [DOI: 10.1039/b815339f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
37
|
Eguchi Y, Utsumi R. Introduction to Bacterial Signal Transduction Networks. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 631:1-6. [DOI: 10.1007/978-0-387-78885-2_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
38
|
Mitrophanov AY, Groisman EA. Signal integration in bacterial two-component regulatory systems. Genes Dev 2008; 22:2601-11. [PMID: 18832064 DOI: 10.1101/gad.1700308] [Citation(s) in RCA: 265] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Two-component systems (TCSs) and phosphorelays are key mediators of bacterial signal transduction. The signals activating these systems promote the phosphorylated state of a response regulator, which is generally the form that carries out specific functions such as binding to DNA and catalysis of biochemical reactions. An emerging class of proteins-termed TCS connectors-modulate the output of TCSs by affecting the phosphorylation state of response regulators. TCS connectors use different mechanisms of action for signal integration, as well as in the coordination and fine-tuning of cellular processes. Present in both Gram-positive and Gram-negative bacteria, TCS connectors are critical for a variety of physiological functions including sporulation, competence, antibiotic resistance, and the transition to stationary phase.
Collapse
Affiliation(s)
- Alexander Y Mitrophanov
- Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|
39
|
Balaji S, Babu MM, Aravind L. Interplay between network structures, regulatory modes and sensing mechanisms of transcription factors in the transcriptional regulatory network of E. coli. J Mol Biol 2007; 372:1108-1122. [PMID: 17706247 PMCID: PMC2422858 DOI: 10.1016/j.jmb.2007.06.084] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 06/18/2007] [Accepted: 06/26/2007] [Indexed: 01/14/2023]
Abstract
Though the bacterial transcription regulation apparatus is distinct in terms of several structural and functional features from its eukaryotic counterpart, the gross structure of the transcription regulatory network (TRN) is believed to be similar in both superkingdoms. Here, we explore the fine structure of the bacterial TRN and the underlying "co-regulatory network" (CRN) to show that despite the superficial similarities to the TRN of the eukaryotic model organism yeast, the bacterial networks display entirely different organizational principles. In particular unlike in eukaryotes, hubs of the bacterial networks are both global regulators and integrators of diverse disparate transcriptional responses. These and other organizational differences might correlate with the fundamental differences in gene and promoter organization in the two superkingdoms, especially the presence of operons and regulons in bacteria. Further we explored to find the interplay, if any, between network structures, mode of regulatory interactions and signal sensing of transcription factors (TFs) in shaping up the bacterial transcriptional regulatory responses. For this purpose, we first classified TFs according to their regulatory mode (activator, repressor or dual regulator) and sensory mechanism (one-component systems responding to internal or external signals, TFs from two-component systems and chromosomal structure modifying TFs) in the bacterial model organism Escherichia coli and then we studied the overall evolutionary optimization of network structures. The incorporation of TFs in different hierarchical elements of the TRN appears to involve on a multi-dimensional selection process depending on regulatory and sensory modes of TFs in motifs, co-regulatory associations between TFs of different functional classes and transcript half-lives. As a result it appears to have generated circuits that allow intricately regulated physiological state changes. We identified the biological significance of most of these optimizations, which can be further used as the basis to explore similar controls in other bacteria. We also show that, though on the larger evolutionary scale, unrelated TFs have evolved to become hubs, within lineages like gamma-proteobacteria there is strong tendency to retain hubs, as well as certain higher-order network modules that have emerged through lineage specific paralog duplications.
Collapse
Affiliation(s)
- S Balaji
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| |
Collapse
|
40
|
Hutchison CE, Kieber JJ. Signaling via Histidine-Containing Phosphotransfer Proteins in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2007; 2:287-289. [PMID: 19704684 PMCID: PMC2634153 DOI: 10.4161/psb.2.4.4039] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Accepted: 02/20/2007] [Indexed: 05/27/2023]
Abstract
The Arabidopsis genome encodes a number of proteins with similarity to two-component phosphorelay signaling elements, including hybrid receptor histidine kinases, two classes of response regulator proteins (type-A and type-B ARRs) and a family of six histidine-containing phosphotransfer proteins (AHPs), five of which contain a conserved His residue that is required for phosphorelay signaling. The current model for cytokinin signaling includes a multistep phosphorelay: three histidine kinases and at least five type-B ARRs have been shown to act as positive regulators of cytokinin signaling, while a number of type-A ARRs, and AHP6, act as negative regulators of the pathway. In our recent Plant Cell paper, we provided genetic evidence that at least four AHPs can act as positive regulators of cytokinin signaling, affecting responses to cytokinin in the root and the shoot. In this addendum, we discuss the role of AHPs in cytokinin signaling and speculate on their potential interactions with other signaling pathways in Arabidopsis.
Collapse
Affiliation(s)
- Claire E Hutchison
- Department of Biology; University of North Carolina; Chapel Hill, North Carolina USA
| | | |
Collapse
|
41
|
Clewell DB. Properties of Enterococcus faecalis plasmid pAD1, a member of a widely disseminated family of pheromone-responding, conjugative, virulence elements encoding cytolysin. Plasmid 2007; 58:205-27. [PMID: 17590438 DOI: 10.1016/j.plasmid.2007.05.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2007] [Revised: 05/02/2007] [Accepted: 05/12/2007] [Indexed: 11/23/2022]
Abstract
The 60-kb pAD1 represents a large and widely disseminated family of conjugative, pheromone-responding, virulence plasmids commonly found in clinical isolates of Enterococcus faecalis. It encodes a hemolysin/bacteriocin (cytolysin) shown to contribute to virulence in animal models, and the related bacteriocin is active against a wide variety of Gram-positive bacteria. This review summarizes what is currently known about the molecular biology of pAD1, including aspects of its cytolytic, UV-resistance, replication, maintenance, and conjugative properties.
Collapse
Affiliation(s)
- Don B Clewell
- Department of Biologic and Materials Sciences, School of Dentistry, The University of Michigan, Ann Arbor, MI 48109-1078, USA.
| |
Collapse
|
42
|
Hutchison CE, Li J, Argueso C, Gonzalez M, Lee E, Lewis MW, Maxwell BB, Perdue TD, Schaller GE, Alonso JM, Ecker JR, Kieber JJ. The Arabidopsis histidine phosphotransfer proteins are redundant positive regulators of cytokinin signaling. THE PLANT CELL 2006; 18:3073-87. [PMID: 17122069 PMCID: PMC1693944 DOI: 10.1105/tpc.106.045674] [Citation(s) in RCA: 316] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 09/01/2006] [Accepted: 10/30/2006] [Indexed: 05/12/2023]
Abstract
Arabidopsis thaliana histidine phosphotransfer proteins (AHPs) are similar to bacterial and yeast histidine phosphotransfer proteins (HPts), which act in multistep phosphorelay signaling pathways. A phosphorelay pathway is the current model for cytokinin signaling. To assess the role of AHPs in cytokinin signaling, we isolated T-DNA insertions in the five AHP genes that are predicted to encode functional HPts and constructed multiple insertion mutants, including an ahp1,2,3,4,5 quintuple mutant. Single ahp mutants were indistinguishable from wild-type seedlings in cytokinin response assays. However, various higher-order mutants displayed reduced sensitivity to cytokinin in diverse cytokinin assays, indicating both a positive role for AHPs in cytokinin signaling and functional overlap among the AHPs. In contrast with the other four AHPs, AHP4 may play a negative role in some cytokinin responses. The quintuple ahp mutant showed various abnormalities in growth and development, including reduced fertility, increased seed size, reduced vascular development, and a shortened primary root. These data indicate that most of the AHPs are redundant, positive regulators of cytokinin signaling and affect multiple aspects of plant development.
Collapse
Affiliation(s)
- Claire E Hutchison
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Molle V, Zanella-Cleon I, Robin JP, Mallejac S, Cozzone AJ, Becchi M. Characterization of the phosphorylation sites of Mycobacterium tuberculosis serine/threonine protein kinases, PknA, PknD, PknE, and PknH by mass spectrometry. Proteomics 2006; 6:3754-66. [PMID: 16739134 DOI: 10.1002/pmic.200500900] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In Mycobacterium tuberculosis (Mtb), regulatory phosphorylation of proteins at serine and/or threonine residues by serine/threonine protein kinases (STPKs) is an emerging theme connected with the involvement of these enzymes in virulence mechanisms. The identification of phosphorylation sites in proteins provides a powerful tool to study signal transduction pathways and to identify the corresponding interaction networks. Detection of phosphorylated proteins as well as assignment of the phosphorylated sites in STPKs is a major challenge in proteomics since some of these enzymes might be interesting therapeutical targets. Using different strategies to identify phosphorylated residues, we report, in the present work, MS studies of the entire intracellular regions of recombinant protein kinases PknA, PknD, PknE, and PknH from Mtb. The on-target dephosphorylation/MALDI-TOF for identification of phosphorylated peptides was used in combination with LC-ESI/MS/MS for localization of phosphorylation sites. By doing so, seven and nine phosphorylated serine and/or threonine residues were identified as phosphorylation sites in the recombinant intracellular regions of PknA and PknH, respectively. The same technique led also to the identification of seven phosphorylation sites in each of the two recombinant kinases, PknD and PknE.
Collapse
Affiliation(s)
- Virginie Molle
- Institute of Biology and Chemistry of Proteins, CNRS/University of Lyon, IFR128, 7 passage du Vercors, 69367 Lyon Cedex 07, France
| | | | | | | | | | | |
Collapse
|
44
|
Cashin P, Goldsack L, Hall D, O'Toole R. Contrasting signal transduction mechanisms in bacterial and eukaryotic gene transcription. FEMS Microbiol Lett 2006; 261:155-64. [PMID: 16907715 DOI: 10.1111/j.1574-6968.2006.00295.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
All known cell types use signal transduction systems to respond to an extracellular or intracellular event. The role of these systems can be to adapt to environmental changes or simply to maintain homeostasis. Cells detect and respond to stimuli in a number of ways. Here we review the mechanisms involved in the transmission of a signal from point of detection to site of action. In particular, a comparison is made between the signalling networks which function in gene transcription in bacterial and eukaryotic cells. Knowledge of the similarities between the systems found in the two types of cells can provide a better understanding of the function and origin of signalling components. In addition, the divergence evident can be exploited by molecules that modulate or disrupt the function of differential signalling mechanisms.
Collapse
Affiliation(s)
- Phillipa Cashin
- School of Biological Sciences, Victoria University of Wellington, New Zealand
| | | | | | | |
Collapse
|
45
|
Gupta S, Sinha A, Sarkar D. Transcriptional autoregulation byMycobacterium tuberculosisPhoP involves recognition of novel direct repeat sequences in the regulatory region of the promoter. FEBS Lett 2006; 580:5328-38. [PMID: 16979633 DOI: 10.1016/j.febslet.2006.09.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 08/22/2006] [Accepted: 09/01/2006] [Indexed: 10/24/2022]
Abstract
The PhoP-PhoR two-component system is essential for virulence and intracellular growth of Mycobacterium tuberculosis (MTB) in human and mouse macrophages or in mice. Here, PhoP and truncated PhoR sensor proteins were shown to participate in phosphotransfer reactions using conserved residues characteristic of two-component signaling systems. beta-Galactosidase activity originating from phoP promoter-lacZ construct was inhibited in presence of PhoP, suggesting transcriptional auto-inhibition by the response regulator. In vitro binding of PhoP is consistent with the in vivo transcriptional repression, indicating phosphorylation-independent assembly of the transcription initiation complex at elevated concentrations of PhoP. DNaseI protection studies reveal a consensus recognition sequence within the phoP promoter that includes three 9-bp direct repeat units. Each repeat unit adjusts to the consensus (1)AC(T)/(G)(T)/(G)(T)/(G)P(y)AP(u)C(9). Alteration in the sequence of the newly-identified direct repeat units relieved phoP transcriptional repression in presence of PhoP, suggesting that PhoP represses its own expression by sequence-specific interaction(s) with the repeat units. Together, these results identify so far unknown PhoP-regulated genetic determinants in the regulatory region of the phoP promoter that are central to understanding of how PhoP may possibly function as a global regulator in MTB.
Collapse
Affiliation(s)
- Sankalp Gupta
- Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | | | | |
Collapse
|
46
|
Shrivastava R, Das DR, Wiker HG, Das AK. Functional insights from the molecular modelling of a novel two-component system. Biochem Biophys Res Commun 2006; 344:1327-33. [PMID: 16650822 DOI: 10.1016/j.bbrc.2006.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 04/04/2006] [Indexed: 10/24/2022]
Abstract
Two-component systems (TCSs) are the major signalling pathway in bacteria and represent potential drug targets. Among the 11 paired TCS proteins present in Mycobacterium tuberculosis H37Rv, the histidine kinases (HKs) Rv0600c (HK1) and Rv0601c (HK2) are annotated to phosphorylate one response regulator (RR) Rv0602c (TcrA). We wanted to establish the sequence-structure-function relationship to elucidate the mechanism of phosphotransfer using in silico methods. Sequence alignments and codon usage analysis showed that the two domains encoded by a single gene in homologous HKs have been separated into individual open-reading frames in M. tuberculosis. This is the first example where two incomplete HKs are involved in phosphorylating a single RR. The model shows that HK2 is a unique histidine phosphotransfer (HPt)-mono-domain protein, not found as lone protein in other bacteria. The secondary structure of HKs was confirmed using "far-UV" circular dichroism study of purified proteins. We propose that HK1 phosphorylates HK2 at the conserved H131 and the phosphoryl group is then transferred to D73 of TcrA.
Collapse
Affiliation(s)
- Rashmi Shrivastava
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India
| | | | | | | |
Collapse
|
47
|
Nadler C, Shifrin Y, Nov S, Kobi S, Rosenshine I. Characterization of enteropathogenic Escherichia coli mutants that fail to disrupt host cell spreading and attachment to substratum. Infect Immun 2006; 74:839-49. [PMID: 16428726 PMCID: PMC1360345 DOI: 10.1128/iai.74.2.839-849.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Upon infection of host cells, enteropathogenic Escherichia coli (EPEC) delivers a set of effector proteins into the host cell cytoplasm via the type III secretion system (TTSS). The effectors subvert various host cell functions. We found that EPEC interferes with the spreading and ultimately with the attachment of suspended fibroblasts or epithelial cells, and we isolated mini-Tn10kan insertion mutants that failed to similarly affect host cells. In most mutants, the insertion sites were mapped to genes encoding TTSS components, including cesD, escC, escJ, escV, espD, sepL, espB, and escF. Other mutants contained insertions in micC or upstream of bfpP, yehL, or ydeP. The insertion upstream of ydeP was associated with a reduction in TTSS protein production and was studied further. To determine whether the apparent repression was due to constitutive expression of the downstream encoded genes, ydeP and ydeO expression vectors were constructed. Expression of recombinant YdeP, YdeO, or EvgA, a positive regulator of both ydeP and ydeO, repressed TTSS protein production. Our results suggest that upon activation of the EvgAS two-component system, EvgA (the response regulator) activates both ydeP and ydeO expression and that YdeP and YdeO act conjointly, directly or indirectly repressing expression of the TTSS genes.
Collapse
Affiliation(s)
- Chen Nadler
- Department of Molecular Genetics and Biotechnology, Faculty of Medicine, The Hebrew University, POB 12272, Jerusalem 91120, Israel
| | | | | | | | | |
Collapse
|
48
|
Panadero J, Pallotti C, Rodríguez-Vargas S, Randez-Gil F, Prieto JA. A Downshift in Temperature Activates the High Osmolarity Glycerol (HOG) Pathway, Which Determines Freeze Tolerance in Saccharomyces cerevisiae. J Biol Chem 2006; 281:4638-45. [PMID: 16371351 DOI: 10.1074/jbc.m512736200] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanisms that enable yeast cells to detect and transmit cold signals and their physiological significance in the adaptive response to low temperatures are unknown. Here, we have demonstrated that the MAPK Hog1p is specifically activated in response to cold. Phosphorylation of Hog1p was dependent on Pbs2p, the MAPK kinase (MAPKK) of the high osmolarity glycerol (HOG) pathway, and Ssk1p, the response regulator of the two-component system Sln1p-Ypd1p. However, Sho1p was not required. Interestingly, phosphorylation of Hog1p was stimulated at 30 degrees C in cells exposed to the membrane rigidifier agent dimethyl sulfoxide. Moreover, Hog1p activation occurred specifically through the Sln1 branch. This suggests that Sln1p monitors changes in membrane fluidity caused by cold. Quite remarkably, activation of Hog1p at low temperatures affected the transcriptional response to cold shock. Indeed, the absence of Hog1p impaired the cold-instigated expression of genes for trehalose- and glycerol-synthesizing enzymes and small chaperones. Moreover, a downward transfer to 12 or 4 degrees C stimulated the overproduction of glycerol in a Hog1p-dependent manner. However, hog1Delta mutant cells showed no growth defects at 12 degrees C as compared with the wild type. On the contrary, deletion of HOG1 or GPD1 decreased tolerance to freezing of wild-type cells preincubated at a low temperature, whereas no differences could be detected in cells shifted directly from 30 to -20 degrees C. Thus, exposure to low temperatures triggered a Hog1p-dependent accumulation of glycerol, which is essential for freeze protection.
Collapse
Affiliation(s)
- Joaquín Panadero
- Department of Biotechnology, Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas, P. O. Box 73, E-46100-Burjassot Valencia, Spain
| | | | | | | | | |
Collapse
|
49
|
Lioliou EE, Mimitou EP, Grigoroudis AI, Panagiotidis CH, Panagiotidis CA, Kyriakidis DA. Phosphorylation activity of the response regulator of the two-component signal transduction system AtoS–AtoC in E. coli. Biochim Biophys Acta Gen Subj 2005; 1725:257-68. [PMID: 16153782 DOI: 10.1016/j.bbagen.2005.06.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 06/30/2005] [Accepted: 06/30/2005] [Indexed: 10/25/2022]
Abstract
Antizyme, long known to be a non-competitive inhibitor of ornithine decarboxylase, is encoded by the atoC gene in Escherichia coli. The present study reveals another role for AtoC, that of a response regulator of the AtoS-AtoC two component system regulating the expression of the atoDAEB operon upon acetoacetate induction. This operon encodes enzymes involved in short-chain fatty acid catabolism in E. coli. Evidence is presented to show that AtoS is a sensor kinase that together with AtoC constitutes a two-component signal transduction system. AtoS is a membrane protein which can autophosphorylate and then transfer that phosphoryl group to AtoC. This process can also be reproduced in vitro. AtoC contains in its amino acid sequence a conserved aspartic acid (D55), which is the putative phosphorylation site, as well as an unexpected "H box" consensus sequence (SHETRTPV), common to histidine kinases, with the histidine contained therein (H73) being a second potential target for phosphorylation. Substitution of either D55 or H73 in His10-AtoC diminished but did not abrogate AtoC phosphorylation suggesting that either both residues can be phosphorylated independently or that the phosphate group can be transferred between them. However, the D55 mutation in comparison to H73 had a more pronounced effect in vivo, on the activation of atoDAEB promoter after acetoacetate induction, although it was the presence of both mutations that rendered AtoC totally unresponsive to induction. These data provide evidence that the gene products of atoS and atoC constitute a two-component signal transduction system, with some unusual properties, involved in the regulation of the atoDAEB operon.
Collapse
Affiliation(s)
- Efthimia E Lioliou
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | | | | | | | | | | |
Collapse
|
50
|
Croxatto A, Pride J, Hardman A, Williams P, Cámara M, Milton DL. A distinctive dual-channel quorum-sensing system operates in Vibrio anguillarum. Mol Microbiol 2004; 52:1677-89. [PMID: 15186417 DOI: 10.1111/j.1365-2958.2004.04083.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many bacterial cells communicate using diffusible signal molecules to monitor cell population density via a process termed quorum sensing. In marine Vibrio species, the Vibrio harveyi-type LuxR protein is a key player in a quorum-sensing phosphorelay cascade, which controls the expression of virulence, symbiotic and survival genes. Previously, we characterized Vibrio anguillarum homologues of LuxR (VanT) and LuxMN (VanMN) and, in this study, we have identified homologues of LuxPQ (VanPQ) and LuxOU (VanOU). In contrast to other Vibrio species, vanT was expressed at low cell density and showed no significant induction as the cell number increased. In addition, although the loss of VanO increased vanT expression, the loss of VanU, unexpectedly, decreased it. Both VanN and VanQ were required for repression of vanT even in a vanU mutant, suggesting an alternative route for VanNQ signal transduction other than via VanU. VanT negatively regulated its own expression by binding and repressing the vanT promoter and by binding and activating the vanOU promoter. The signal relay results in a cellular response as expression of the metalloprotease, empA, was altered similar to that of vanT in all the mutants. Consequently, the V. anguillarum quorum-sensing phosphorelay systems work differently from those of V. harveyi and may be used to limit rather than induce vanT expression.
Collapse
Affiliation(s)
- Antony Croxatto
- Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden
| | | | | | | | | | | |
Collapse
|