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Vander Griend JA, Isenberg RY, Kotla KR, Mandel MJ. Transcriptional pathways across colony biofilm models in the symbiont Vibrio fischeri. mSystems 2024; 9:e0081523. [PMID: 38126773 PMCID: PMC10804989 DOI: 10.1128/msystems.00815-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/16/2023] [Indexed: 12/23/2023] Open
Abstract
Beneficial microbial symbionts that are horizontally acquired by their animal hosts undergo a lifestyle transition from free-living in the environment to associating with host tissues. In the model symbiosis between the Hawaiian bobtail squid and its microbial symbiont Vibrio fischeri, one mechanism used to make this transition during host colonization is the formation of biofilm-like aggregates in host mucosa. Previous work identified factors that are sufficient to induce V. fischeri biofilm formation, yet much remains unknown regarding the breadth of target genes induced by these factors. Here, we probed two widely used in vitro models of biofilm formation to identify novel regulatory pathways in the squid symbiont V. fischeri ES114. We discovered a shared set of 232 genes that demonstrated similar patterns in expression in both models. These genes comprise multiple exopolysaccharide loci that are upregulated and flagellar motility genes that are downregulated, with a consistent decrease in measured swimming motility. Furthermore, we identified genes regulated downstream of the key sensor kinase RscS that are induced independent of the response regulator SypG. Our data suggest that transcriptional regulator VpsR plays a strong role in expression of at least a subset of these genes. Overall, this study adds to our understanding of the genes involved in V. fischeri biofilm regulation while revealing new regulatory pathways branching from previously characterized signaling networks.IMPORTANCEThe V. fischeri-squid system provides an opportunity to study biofilm development both in the animal host and in culture-based biofilm models that capture key aspects of in vivo signaling. In this work, we report the results of the transcriptomic profiling of two V. fischeri biofilm models followed by phenotypic validation and examination of novel signaling pathway architecture. Remarkable consistency between the models provides a strong basis for future studies using either approach or both. A subset of the factors identified by the approaches were validated in the work, and the body of transcriptomic data provides a number of leads for future studies in culture and during animal colonization.
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Affiliation(s)
- Jacob A. Vander Griend
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ruth Y. Isenberg
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ketan R. Kotla
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Mark J. Mandel
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Zhou CM, Li JX, Zhang TQ, Xu ZG, Ma ML, Zhang P, Wang JW. The structure of B-ARR reveals the molecular basis of transcriptional activation by cytokinin. Proc Natl Acad Sci U S A 2024; 121:e2319335121. [PMID: 38198526 PMCID: PMC10801921 DOI: 10.1073/pnas.2319335121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 12/11/2023] [Indexed: 01/12/2024] Open
Abstract
The phytohormone cytokinin has various roles in plant development, including meristem maintenance, vascular differentiation, leaf senescence, and regeneration. Prior investigations have revealed that cytokinin acts via a phosphorelay similar to the two-component system by which bacteria sense and respond to external stimuli. The eventual targets of this phosphorelay are type-B ARABIDOPSIS RESPONSE REGULATORS (B-ARRs), containing the conserved N-terminal receiver domain (RD), middle DNA binding domain (DBD), and C-terminal transactivation domain. While it has been established for two decades that the phosphoryl transfer from a specific histidyl residue in ARABIDOPSIS HIS PHOSPHOTRANSFER PROTEINS (AHPs) to an aspartyl residue in the RD of B-ARRs results in a rapid transcriptional response to cytokinin, the underlying molecular basis remains unclear. In this work, we determine the crystal structures of the RD-DBD of ARR1 (ARR1RD-DBD) as well as the ARR1DBD-DNA complex from Arabidopsis. Analyses of the ARR1DBD-DNA complex have revealed the structural basis for sequence-specific recognition of the GAT trinucleotide by ARR1. In particular, comparing the ARR1RD-DBD and ARR1DBD-DNA structures reveals that unphosphorylated ARR1RD-DBD exists in a closed conformation with extensive contacts between the RD and DBD. In vitro and vivo functional assays have further suggested that phosphorylation of the RD weakens its interaction with DBD, subsequently permits the DNA binding capacity of DBD, and promotes the transcriptional activity of ARR1. Our findings thus provide mechanistic insights into phosphorelay activation of gene transcription in response to cytokinin.
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Affiliation(s)
- Chuan-Miao Zhou
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
| | - Jian-Xu Li
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
- Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Botanical Garden, Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai201602, China
| | - Tian-Qi Zhang
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
| | - Zhou-Geng Xu
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
| | - Miao-Lian Ma
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
- Key Laboratory of Plant Carbon Capture, Chinese Academy of Sciences, Shanghai200032, China
| | - Jia-Wei Wang
- National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai200032, China
- Key Laboratory of Plant Carbon Capture, Chinese Academy of Sciences, Shanghai200032, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai201210, China
- New Cornerstone Science Laboratory, Shanghai200032, China
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Griend JAV, Isenberg RY, Kotla KR, Mandel MJ. Transcriptional pathways across colony biofilm models in the symbiont Vibrio fischeri. bioRxiv 2023:2023.08.07.552283. [PMID: 37609283 PMCID: PMC10441365 DOI: 10.1101/2023.08.07.552283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Beneficial microbial symbionts that are horizontally acquired by their animal hosts undergo a lifestyle transition from free-living in the environment to associated with host tissues. In the model symbiosis between the Hawaiian bobtail squid and its microbial symbiont Vibrio fischeri, one mechanism used to make this transition during host colonization is the formation of biofilm-like aggregates in host mucosa. Previous work identified factors that are sufficient to induce V. fischeri biofilm formation, yet much remains unknown regarding the breadth of target genes induced by these factors. Here, we probed two widely-used in vitro models of biofilm formation to identify novel regulatory pathways in the squid symbiont V. fischeri ES114. We discovered a shared set of 232 genes that demonstrated similar patterns in expression in both models. These genes comprise multiple exopolysaccharide loci that are upregulated and flagellar motility genes that are downregulated, with a consistent decrease in measured swimming motility. Furthermore, we identified genes regulated downstream of the key sensor kinase RscS that are induced independent of the response regulator SypG. Our data suggest that putative response regulator VpsR plays a strong role in expression of at least a subset of these genes. Overall, this study adds to our understanding of the genes involved in V. fischeri biofilm regulation, while revealing new regulatory pathways branching from previously characterized signaling networks.
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Affiliation(s)
- Jacob A. Vander Griend
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI USA
| | - Ruth Y. Isenberg
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI USA
| | - Ketan R. Kotla
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
| | - Mark J. Mandel
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI USA
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Abstract
The ability of the anaerobic gastrointestinal pathogen Clostridioides difficile to survive outside the host relies on the formation of dormant endospores. Spore formation is contingent on the activation of a conserved transcription factor, Spo0A, by phosphorylation. Multiple kinases and phosphatases regulate Spo0A activity in other spore-forming organisms; however, these factors are not well conserved in C. difficile. Previously, we discovered that deletion of a predicted histidine kinase, CD1492, increases sporulation, indicating that CD1492 inhibits C. difficile spore formation. In this study, we investigate the functions of additional predicted orphan histidine kinases CD2492, CD1579, and CD1949, which are hypothesized to regulate Spo0A phosphorylation. Disruption of CD2492 also increased sporulation frequency, similarly to the CD1492 mutant and in contrast to a previous study. A CD1492 CD2492 mutant phenocopied the sporulation and gene expression patterns of the single mutants, suggesting that these proteins function in the same genetic pathway to repress sporulation. Deletion of CD1579 variably increased sporulation frequency; however, knockdown of CD1949 expression did not influence sporulation. We provide evidence that CD1492, CD2492, and CD1579 function as phosphatases, as mutation of the conserved histidine residue for phosphate transfer abolished CD2492 function, and expression of the CD1492 or CD2492 histidine site-directed mutants or the wild-type CD1579 allele in a parent strain resulted in a dominant-negative hypersporulation phenotype. Altogether, at least three predicted histidine kinases, CD1492, CD2492, and CD1579 (herein, PtpA, PtpB and PtpC), repress C. difficile sporulation initiation by regulating activity of Spo0A. IMPORTANCE The formation of inactive spores is critical for the long-term survival of the gastrointestinal pathogen Clostridioides difficile. The onset of sporulation is controlled by the master regulator of sporulation, Spo0A, which is activated by phosphorylation. Multiple kinases and phosphatases control Spo0A phosphorylation; however, this regulatory pathway is not defined in C. difficile. We show that two predicted histidine kinase proteins, CD1492 (PtpA) and CD2492 (PtpB), function in the same regulatory pathway to repress sporulation by preventing Spo0A phosphorylation. We show that another predicted histidine kinase protein, CD1579 (PtpC), also represses sporulation and present evidence that a fourth predicted histidine kinase protein, CD1949, does not impact sporulation. These results support the idea that C. difficile inhibits sporulation initiation through multiple phosphatases.
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Yu CC, Lin PC, Chiang CH, Jen ST, Lai YL, Hsu SC, Lo LC, Lin JJ, Chan NL, Yu MJ. Sequential Phosphorylation of Hepatitis C Virus NS5A Protein Requires the ATP-Binding Domain of NS3 Helicase. J Virol 2022;:e0010722. [PMID: 35293767 DOI: 10.1128/jvi.00107-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The propagation of the hepatitis C virus (HCV) is regulated in part by the phosphorylation of its nonstructural protein NS5A that undergoes sequential phosphorylation on several highly conserved serine residues and switches from a hypo- to a hyperphosphorylated state. Previous studies have shown that NS5A sequential phosphorylation requires NS3 encoded on the same NS3-NS4A-NS4B-NS5A polyprotein. Subtle mutations in NS3 without affecting its protease activity could affect NS5A phosphorylation. Given the ATPase domain in the NS3 COOH terminus, we tested whether NS3 participates in NS5A phosphorylation similarly to the nucleoside diphosphate kinase-like activity of the rotavirus NSP2 nucleoside triphosphatase (NTPase). Mutations in the NS3 ATP-binding motifs blunted NS5A hyperphosphorylation and phosphorylation at serines 225, 232, and 235, whereas a mutation in the RNA-binding domain did not. The phosphorylation events were not rescued with wild-type NS3 provided in trans. When provided with an NS3 ATPase-compatible ATP analog, N6-benzyl-ATP-γ-S, thiophosphorylated NS5A was detected in the cells expressing the wild-type NS3-NS5B polyprotein. The thiophosphorylation level was lower in the cells expressing NS3-NS5B with a mutation in the NS3 ATP-binding domain. In vitro assays with a synthetic peptide and purified wild-type NS3 followed by dot blotting and mass spectrometry found weak NS5A phosphorylation at serines 222 and 225 that was sensitive to an inhibitor of casein kinase Iα but not helicase. When casein kinase Iα was included in the assay, much stronger phosphorylation was observed at serines 225, 232, and 235. We concluded that NS5A sequential phosphorylation requires the ATP-binding domain of the NS3 helicase and that casein kinase Iα is a potent NS5A kinase. IMPORTANCE For more than 20 years, NS3 was known to participate in NS5A sequential phosphorylation. In the present study, we show for the first time that the ATP-binding domain of NS3 is involved in NS5A phosphorylation. In vitro assays showed that casein kinase Iα is a very potent kinase responsible for NS5A phosphorylation at serines 225, 232, and 235. Our data suggest that ATP binding by NS3 probably results in conformational changes that recruit casein kinase Iα to phosphorylate NS5A, initially at S225 and subsequently at S232 and S235. Our discovery reveals intricate requirements of the structural integrity of NS3 for NS5A hyperphosphorylation and HCV replication.
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Tran LH, Urbanowicz A, Jasiński M, Jaskolski M, Ruszkowski M. 3D Domain Swapping Dimerization of the Receiver Domain of Cytokinin Receptor CRE1 From Arabidopsis thaliana and Medicago truncatula. Front Plant Sci 2021; 12:756341. [PMID: 34630499 PMCID: PMC8498639 DOI: 10.3389/fpls.2021.756341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 08/30/2021] [Indexed: 06/13/2023]
Abstract
Cytokinins are phytohormones regulating many biological processes that are vital to plants. CYTOKININ RESPONSE1 (CRE1), the main cytokinin receptor, has a modular architecture composed of a cytokinin-binding CHASE (Cyclases/Histidine kinases Associated Sensory Extracellular) domain, followed by a transmembrane fragment, an intracellular histidine kinase (HK) domain, and a receiver domain (REC). Perception of cytokinin signaling involves (i) a hormone molecule binding to the CHASE domain, (ii) CRE1 autophosphorylation at a conserved His residue in the HK domain, followed by a phosphorelay to (iii) a conserved Asp residue in the REC domain, (iv) a histidine-containing phosphotransfer protein (HPt), and (v) a response regulator (RR). This work focuses on the crystal structures of the REC domain of CRE1 from the model plant Arabidopsis thaliana and from the model legume Medicago truncatula. Both REC domains form tight 3D-domain-swapped dimers. Dimerization of the REC domain agrees with the quaternary assembly of the entire CRE1 but is incompatible with a model of its complex with HPt, suggesting that a considerable conformational change should occur to enable the signal transduction. Indeed, phosphorylation of the REC domain can change the HPt-binding properties of CRE1, as shown by functional studies.
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Affiliation(s)
- Linh H. Tran
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
| | - Anna Urbanowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
| | - Michał Jasiński
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
- Department of Biochemistry and Biotechnology, Poznan University of Life Sciences, Poznań, Poland
| | - Mariusz Jaskolski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
- Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, Poznań, Poland
| | - Milosz Ruszkowski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
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Ludvik DA, Bultman KM, Mandel MJ. Hybrid Histidine Kinase BinK Represses Vibrio fischeri Biofilm Signaling at Multiple Developmental Stages. J Bacteriol 2021; 203:e0015521. [PMID: 34031036 DOI: 10.1128/JB.00155-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and its exclusive light organ symbiont, Vibrio fischeri, provides a natural system in which to study host-microbe specificity and gene regulation during the establishment of a mutually beneficial symbiosis. Colonization of the host relies on bacterial biofilm-like aggregation in the squid mucus field. Symbiotic biofilm formation is controlled by a two-component signaling (TCS) system consisting of regulators RscS-SypF-SypG, which together direct transcription of the symbiosis polysaccharide Syp. TCS systems are broadly important for bacteria to sense environmental cues and then direct changes in behavior. Previously, we identified the hybrid histidine kinase BinK as a strong negative regulator of V. fischeri biofilm regulation, and here we further explore the function of BinK. To inhibit biofilm formation, BinK requires the predicted phosphorylation sites in both the histidine kinase (H362) and receiver (D794) domains. Furthermore, we show that RscS is not essential for host colonization when binK is deleted from strain ES114, and imaging of aggregate size revealed no benefit to the presence of RscS in a background lacking BinK. Strains lacking RscS still suffered in competition. Finally, we show that BinK functions to inhibit biofilm gene expression in the light organ crypts, providing evidence for biofilm gene regulation at later stages of host colonization. Overall, this study provides direct evidence for opposing activities of RscS and BinK and yields novel insights into biofilm regulation during the maturation of a beneficial symbiosis. IMPORTANCE Bacteria are often in a biofilm state, and transitions between planktonic and biofilm lifestyles are important for pathogenic, beneficial, and environmental microbes. The critical nature of biofilm formation during Vibrio fischeri colonization of the Hawaiian bobtail squid light organ provides an opportunity to study development of this process in vivo using a combination of genetic and imaging approaches. The current work refines the signaling circuitry of the biofilm pathway in V. fischeri, provides evidence that biofilm regulatory changes occur in the host, and identifies BinK as one of the regulators of that process. This study provides information about how bacteria regulate biofilm gene expression in an intact animal host.
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Hoang XLT, Prerostova S, Thu NBA, Thao NP, Vankova R, Tran LSP. Histidine Kinases: Diverse Functions in Plant Development and Responses to Environmental Conditions. Annu Rev Plant Biol 2021; 72:297-323. [PMID: 34143645 DOI: 10.1146/annurev-arplant-080720-093057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The two-component system (TCS), which is one of the most evolutionarily conserved signaling pathway systems, has been known to regulate multiple biological activities and environmental responses in plants. Significant progress has been made in characterizing the biological functions of the TCS components, including signal receptor histidine kinase (HK) proteins, signal transducer histidine-containing phosphotransfer proteins, and effector response regulator proteins. In this review, our scope is focused on the diverse structure, subcellular localization, and interactions of the HK proteins, as well as their signaling functions during development and environmental responses across different plant species. Based on data collected from scientific studies, knowledge about acting mechanisms and regulatory roles of HK proteins is presented. This comprehensive summary ofthe HK-related network provides a panorama of sophisticated modulating activities of HK members and gaps in understanding these activities, as well as the basis for developing biotechnological strategies to enhance the quality of crop plants.
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Affiliation(s)
- Xuan Lan Thi Hoang
- Applied Biotechnology for Crop Development Research Unit, School of Biotechnology, International University, Ho Chi Minh City 700000, Vietnam; , ,
- Vietnam National University, Ho Chi Minh City 700000, Vietnam
| | - Sylva Prerostova
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague 6, Czech Republic; ,
| | - Nguyen Binh Anh Thu
- Applied Biotechnology for Crop Development Research Unit, School of Biotechnology, International University, Ho Chi Minh City 700000, Vietnam; , ,
- Vietnam National University, Ho Chi Minh City 700000, Vietnam
| | - Nguyen Phuong Thao
- Applied Biotechnology for Crop Development Research Unit, School of Biotechnology, International University, Ho Chi Minh City 700000, Vietnam; , ,
- Vietnam National University, Ho Chi Minh City 700000, Vietnam
| | - Radomira Vankova
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague 6, Czech Republic; ,
| | - Lam-Son Phan Tran
- Institute of Genomics for Crop Abiotic Stress Tolerance, Department of Plant and Soil Science, Texas Tech University, Lubbock, Texas 79409, USA;
- Stress Adaptation Research Unit, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan
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Bühring S, Yemelin A, Michna T, Tenzer S, Jacob S. Evidence of a New MoYpd1p Phosphotransferase Isoform in the Multistep Phosphorelay System of Magnaporthe oryzae. J Fungi (Basel) 2021; 7:jof7050389. [PMID: 34063560 PMCID: PMC8156605 DOI: 10.3390/jof7050389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/05/2021] [Accepted: 05/14/2021] [Indexed: 01/01/2023] Open
Abstract
Different external stimuli are perceived by multiple sensor histidine kinases and transmitted by phosphorylation via the phosphotransfer protein Ypd1p in the multistep phosphorelay system of the high osmolarity glycerol signaling pathway of filamentous fungi. How the signal propagation takes place is still not known in detail since multiple sensor histidine kinase genes in most filamentous fungi are coded in the genome, whereas only one gene for Ypd1p exists. That raises the hypothesis that various Ypd1p isoforms are produced from a single gene sequence, perhaps by alternative splicing, facilitating a higher variability in signal transduction. We found that the mRNA of MoYPD1 in the rice blast fungus Magnaporthe oryzae is subjected to an increased structural variation and amplified putative isoforms on a cDNA level. We then generated mutant strains overexpressing these isoforms, purified the products, and present here one previously unknown MoYpd1p isoform on a proteome level. Alternative splicing was found to be a valid molecular mechanism to increase the signal diversity in eukaryotic multistep phosphorelay systems.
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Affiliation(s)
- Sri Bühring
- Institute for Biotechnology and Drug Research gGmbH, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany; (S.B.); (A.Y.)
| | - Alexander Yemelin
- Institute for Biotechnology and Drug Research gGmbH, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany; (S.B.); (A.Y.)
| | - Thomas Michna
- Institut für Immunologie, Universitätsmedizin der Johannes-Gutenberg Universität Mainz, Langenbeckstr. 1, 55131 Mainz, Germany; (T.M.); (S.T.)
| | - Stefan Tenzer
- Institut für Immunologie, Universitätsmedizin der Johannes-Gutenberg Universität Mainz, Langenbeckstr. 1, 55131 Mainz, Germany; (T.M.); (S.T.)
| | - Stefan Jacob
- Institute for Biotechnology and Drug Research gGmbH, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany; (S.B.); (A.Y.)
- Correspondence:
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Bourret RB, Kennedy EN, Foster CA, Sepúlveda VE, Goldman WE. A Radical Reimagining of Fungal Two-Component Regulatory Systems. Trends Microbiol 2021; 29:883-893. [PMID: 33853736 DOI: 10.1016/j.tim.2021.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 11/17/2022]
Abstract
Bacterial two-component regulatory systems (TCSs) mediate signal transduction by transferring phosphoryl groups between sensor kinase and response regulator proteins, sometimes using intermediary histidine-phosphotransferase (Hpt) domains to form multistep phosphorelays. Because (i) almost all known fungal sensor kinases exhibit a domain architecture characteristic of bacterial TCS phosphorelays, (ii) all known fungal Hpts are stand-alone proteins suited to shuttle between cytoplasm and nucleus, and (iii) the best-characterized fungal TCS is a canonical phosphorelay, it is widely assumed that most or all fungal TCSs function via phosphorelays. However, fungi generally encode more sensor kinases than Hpts or response regulators, leading to a disparity between putative phosphorelay inputs and outputs. The simplest resolution of this paradox is to hypothesize that most fungal sensor kinases do not participate in phosphorelays. Reimagining how fungal TCSs might function leads to multiple testable predictions.
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Affiliation(s)
- Robert B Bourret
- Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA.
| | - Emily N Kennedy
- Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - Clay A Foster
- Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - Victoria E Sepúlveda
- Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - William E Goldman
- Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA
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Farrera-Calderon RG, Pallegar P, Westbye AB, Wiesmann C, Lang AS, Beatty JT. The CckA-ChpT-CtrA Phosphorelay Controlling Rhodobacter capsulatus Gene Transfer Agent Production Is Bidirectional and Regulated by Cyclic di-GMP. J Bacteriol 2021; 203:e00525-20. [PMID: 33288624 DOI: 10.1128/JB.00525-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022] Open
Abstract
Protein phosphorylation is a universal mechanism for transducing cellular signals in prokaryotes and eukaryotes. The histidine kinase CckA, the histidine phosphotransferase ChpT, and the response regulator CtrA are conserved throughout the alphaproteobacteria. In Rhodobacter capsulatus, these proteins are key regulators of the gene transfer agent (RcGTA), which is present in several alphaproteobacteria. Using purified recombinant R. capsulatus proteins, we show in vitro autophosphorylation of CckA protein, and phosphotransfer to ChpT and thence to CtrA, to demonstrate biochemically that they form a phosphorelay. The secondary messenger cyclic di-GMP changed CckA from a kinase to a phosphatase, resulting in reversal of the phosphotransfer flow in the relay. The substitutions of two residues in CckA greatly affected the kinase or phosphatase activity of the protein in vitro, and production of mutant CckA proteins in vivo confirmed the importance of kinase but not phosphatase activity for the lytic release of RcGTA. However, phosphatase activity was needed to produce functional RcGTA particles. The binding of cyclic di-GMP to the wild-type and mutant CckA proteins was evaluated directly using a pulldown assay based on biotinylated cyclic di-GMP and streptavidin-linked beads.IMPORTANCE The CckA, ChpT, and CtrA phosphorelay proteins are widespread in the alphaproteobacteria, and there are two groups of organisms that differ in terms of whether this pathway is essential for cell viability. Little is known about the biochemical function of these proteins in organisms where the pathway is not essential, a group that includes Rhodobacter capsulatus This work demonstrates biochemically that CckA, ChpT, and CtrA also form a functional phosphorelay in the latter group and that the direction of phosphotransfer is reversed by cyclic di-GMP. It is important to improve understanding of more representatives of this pathway in order to obtain deeper insight into the function, composition, and evolutionary significance of a wider range of bacterial regulatory networks.
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Coppine J, Kaczmarczyk A, Petit K, Brochier T, Jenal U, Hallez R. Regulation of Bacterial Cell Cycle Progression by Redundant Phosphatases. J Bacteriol 2020; 202:e00345-20. [PMID: 32571969 DOI: 10.1128/JB.00345-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 06/16/2020] [Indexed: 11/20/2022] Open
Abstract
In the model organism Caulobacter crescentus, a network of two-component systems involving the response regulators CtrA, DivK, and PleD coordinates cell cycle progression with differentiation. Active phosphorylated CtrA prevents chromosome replication in G1 cells while simultaneously regulating expression of genes required for morphogenesis and development. At the G1-S transition, phosphorylated DivK (DivK∼P) and PleD (PleD∼P) accumulate to indirectly inactivate CtrA, which triggers DNA replication initiation and concomitant cellular differentiation. The phosphatase PleC plays a pivotal role in this developmental program by keeping DivK and PleD phosphorylation levels low during G1, thereby preventing premature CtrA inactivation. Here, we describe CckN as a second phosphatase akin to PleC that dephosphorylates DivK∼P and PleD∼P in G1 cells. However, in contrast to PleC, no kinase activity was detected with CckN. The effects of CckN inactivation are largely masked by PleC but become evident when PleC and DivJ, the major kinase for DivK and PleD, are absent. Accordingly, mild overexpression of cckN restores most phenotypic defects of a pleC null mutant. We also show that CckN and PleC are proteolytically degraded in a ClpXP-dependent way before the onset of the S phase. Surprisingly, known ClpX adaptors are dispensable for PleC and CckN proteolysis, raising the possibility that as yet unidentified proteolytic adaptors are required for the degradation of both phosphatases. Since cckN expression is induced in stationary phase, depending on the stress alarmone (p)ppGpp, we propose that CckN acts as an auxiliary factor responding to environmental stimuli to modulate CtrA activity under suboptimal conditions.IMPORTANCE Two-component signal transduction systems are widely used by bacteria to adequately respond to environmental changes by adjusting cellular parameters, including the cell cycle. In Caulobacter crescentus, PleC acts as a phosphatase that indirectly protects the response regulator CtrA from premature inactivation during the G1 phase of the cell cycle. Here, we provide genetic and biochemical evidence that PleC is seconded by another phosphatase, CckN. The activity of PleC and CckN phosphatases is restricted to the G1 phase since both proteins are degraded by ClpXP protease before the G1-S transition. Degradation is independent of any known proteolytic adaptors and relies, in the case of CckN, on an unsuspected N-terminal degron. Our work illustrates a typical example of redundant functions between two-component proteins.
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Losick R. Concerns about Continuing Claims that a Protein Complex Interacts with the Phosphorelay. mBio 2020; 11:e03371-19. [PMID: 32156829 PMCID: PMC7064785 DOI: 10.1128/mbio.03371-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Richard Losick
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
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Hofmann A, Müller S, Drechsler T, Berleth M, Caesar K, Rohr L, Harter K, Groth G. High-Level Expression, Purification and Initial Characterization of Recombinant Arabidopsis Histidine Kinase AHK1. Plants (Basel) 2020; 9:plants9030304. [PMID: 32121559 PMCID: PMC7154865 DOI: 10.3390/plants9030304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/18/2020] [Accepted: 02/24/2020] [Indexed: 01/16/2023]
Abstract
Plants employ a number of phosphorylation cascades in response to a wide range of environmental stimuli. Previous studies in Arabidopsis and yeast indicate that histidine kinase AHK1 is a positive regulator of drought and osmotic stress responses. Based on these studies AHK1 was proposed a plant osmosensor, although the molecular basis of plant osmosensing still remains unknown. To understand the molecular role and signaling mechanism of AHK1 in osmotic stress, we have expressed and purified full-length AHK1 from Arabidopsis in a bacterial host to allow for studies on the isolated transmembrane receptor. Purification of the recombinant protein solubilized from the host membranes was achieved in a single step by metal-affinity chromatography. Analysis of the purified AHK1 by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting show a single band indicating that the preparation is highly pure and devoid of contaminants or degradation products. In addition, gel filtration experiments indicate that the preparation is homogenous and monodisperse. Finally, CD-spectroscopy, phosphorylation activity, dimerization studies, and protein–protein interaction with plant phosphorylation targeting AHP2 demonstrate that the purified protein is functionally folded and acts as phospho-His or phospho-Asp phosphatase. Hence, the expression and purification of recombinant AHK1 reported here provide a basis for further detailed functional and structural studies of the receptor, which might help to understand plant osmosensing and osmosignaling on the molecular level.
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Affiliation(s)
- Alexander Hofmann
- Institute of Biochemical Plant Physiology, Heinrich Heine University, Düsseldorf 40225, Germany; (A.H.); (S.M.); (M.B.)
| | - Sophia Müller
- Institute of Biochemical Plant Physiology, Heinrich Heine University, Düsseldorf 40225, Germany; (A.H.); (S.M.); (M.B.)
| | - Thomas Drechsler
- Center for Plant Molecular Biology (ZMBP), Eberhard Karls Universität Tübingen, Tübingen 72076, Germany; (T.D.); (K.C.); (L.R.); (K.H.)
| | - Mareike Berleth
- Institute of Biochemical Plant Physiology, Heinrich Heine University, Düsseldorf 40225, Germany; (A.H.); (S.M.); (M.B.)
| | - Katharina Caesar
- Center for Plant Molecular Biology (ZMBP), Eberhard Karls Universität Tübingen, Tübingen 72076, Germany; (T.D.); (K.C.); (L.R.); (K.H.)
| | - Leander Rohr
- Center for Plant Molecular Biology (ZMBP), Eberhard Karls Universität Tübingen, Tübingen 72076, Germany; (T.D.); (K.C.); (L.R.); (K.H.)
| | - Klaus Harter
- Center for Plant Molecular Biology (ZMBP), Eberhard Karls Universität Tübingen, Tübingen 72076, Germany; (T.D.); (K.C.); (L.R.); (K.H.)
| | - Georg Groth
- Institute of Biochemical Plant Physiology, Heinrich Heine University, Düsseldorf 40225, Germany; (A.H.); (S.M.); (M.B.)
- Correspondence: ; Tel.: +49-211-811-2822
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15
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Rotman ER, Bultman KM, Brooks JF 2nd, Gyllborg MC, Burgos HL, Wollenberg MS, Mandel MJ. Natural Strain Variation Reveals Diverse Biofilm Regulation in Squid-Colonizing Vibrio fischeri. J Bacteriol 2019; 201:e00033-19. [PMID: 30782630 DOI: 10.1128/JB.00033-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 02/07/2019] [Indexed: 12/17/2022] Open
Abstract
The mutualistic symbiont Vibrio fischeri builds a symbiotic biofilm during colonization of squid hosts. Regulation of the exopolysaccharide component, termed Syp, has been examined in strain ES114, where production is controlled by a phosphorelay that includes the inner membrane hybrid histidine kinase RscS. Most strains that lack RscS or encode divergent RscS proteins cannot colonize a squid host unless RscS from a squid symbiont is heterologously expressed. In this study, we examine V. fischeri isolates worldwide to understand the landscape of biofilm regulation during beneficial colonization. We provide a detailed study of three distinct evolutionary groups of V. fischeri and find that while the RscS-Syp biofilm pathway is required in one of the groups, two other groups of squid symbionts require Syp independent of RscS. Mediterranean squid symbionts, including V. fischeri SR5, colonize without an RscS homolog encoded by their genome. Additionally, group A V. fischeri strains, which form a tightly related clade of Hawaii isolates, have a frameshift in rscS and do not require the gene for squid colonization or competitive fitness. These same strains have a frameshift in sypE, and we provide evidence that this group A sypE allele leads to an upregulation in biofilm activity. Thus, this work describes the central importance of Syp biofilm in colonization of diverse isolates and demonstrates that significant evolutionary transitions correspond to regulatory changes in the syp pathway.IMPORTANCE Biofilms are surface-associated, matrix-encased bacterial aggregates that exhibit enhanced protection to antimicrobial agents. Previous work has established the importance of biofilm formation by a strain of luminous Vibrio fischeri bacteria as the bacteria colonize their host, the Hawaiian bobtail squid. In this study, expansion of this work to many natural isolates revealed that biofilm genes are universally required, yet there has been a shuffling of the regulators of those genes. This work provides evidence that even when bacterial behaviors are conserved, dynamic regulation of those behaviors can underlie evolution of the host colonization phenotype. Furthermore, this work emphasizes the importance of investigating natural diversity as we seek to understand molecular mechanisms in bacteria.
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16
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Heindl JE, Crosby D, Brar S, Pinto JF, Singletary T, Merenich D, Eagan JL, Buechlein AM, Bruger EL, Waters CM, Fuqua C. Reciprocal control of motility and biofilm formation by the PdhS2 two-component sensor kinase of Agrobacterium tumefaciens. Microbiology (Reading) 2019; 165:146-162. [PMID: 30620265 PMCID: PMC7003649 DOI: 10.1099/mic.0.000758] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/28/2018] [Indexed: 12/13/2022]
Abstract
A core regulatory pathway that directs developmental transitions and cellular asymmetries in Agrobacterium tumefaciens involves two overlapping, integrated phosphorelays. One of these phosphorelays putatively includes four histidine sensor kinase homologues, DivJ, PleC, PdhS1 and PdhS2, and two response regulators, DivK and PleD. In several different alphaproteobacteria, this pathway influences a conserved downstream phosphorelay that ultimately controls the phosphorylation state of the CtrA master response regulator. The PdhS2 sensor kinase reciprocally regulates biofilm formation and swimming motility. In the current study, the mechanisms by which the A. tumefaciens sensor kinase PdhS2 directs this regulation are delineated. PdhS2 lacking a key residue implicated in phosphatase activity is markedly deficient in proper control of attachment and motility phenotypes, whereas a kinase-deficient PdhS2 mutant is only modestly affected. A genetic interaction between DivK and PdhS2 is revealed, unmasking one of several connections between PdhS2-dependent phenotypes and transcriptional control by CtrA. Epistasis experiments suggest that PdhS2 may function independently of the CckA sensor kinase, the cognate sensor kinase for CtrA, which is inhibited by DivK. Global expression analysis of the pdhS2 mutant reveals a restricted regulon, most likely functioning through CtrA to separately control motility and regulate the levels of the intracellular signal cyclic diguanylate monophosphate (cdGMP), thereby affecting the production of adhesive polysaccharides and attachment. We hypothesize that in A. tumefaciens the CtrA regulatory circuit has expanded to include additional inputs through the addition of PdhS-type sensor kinases, likely fine-tuning the response of this organism to the soil microenvironment.
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Affiliation(s)
- Jason E. Heindl
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Daniel Crosby
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
- Present address: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Sukhdev Brar
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - John F. Pinto
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Tiyan Singletary
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Daniel Merenich
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Justin L. Eagan
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Aaron M. Buechlein
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN 47405, USA
| | - Eric L. Bruger
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
- Present address: Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Christopher M. Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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17
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Teran-Melo JL, Peña-Sandoval GR, Silva-Jimenez H, Rodriguez C, Alvarez AF, Georgellis D. Routes of phosphoryl group transfer during signal transmission and signal decay in the dimeric sensor histidine kinase ArcB. J Biol Chem 2018; 293:13214-13223. [PMID: 29945971 PMCID: PMC6109937 DOI: 10.1074/jbc.ra118.003910] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/14/2018] [Indexed: 11/06/2022] Open
Abstract
The Arc (anoxic redox control) two-component system of Escherichia coli, comprising ArcA as the response regulator and ArcB as the sensor histidine kinase, modulates the expression of numerous genes in response to respiratory growth conditions. Under reducing growth conditions, ArcB autophosphorylates at the expense of ATP, and transphosphorylates ArcA via a His292 → Asp576 → His717 → Asp54 phosphorelay, whereas under oxidizing growth conditions, ArcB catalyzes the dephosphorylation of ArcA-P by a reverse Asp54 → His717 → Asp576 → Pi phosphorelay. However, the exact phosphoryl group transfer routes and the molecular mechanisms determining their directions are unclear. Here, we show that, during signal propagation, the His292 → Asp576 and Asp576 → His717 phosphoryl group transfers within ArcB dimers occur intra- and intermolecularly, respectively. Moreover, we report that, during signal decay, the phosphoryl group transfer from His717 to Asp576 takes place intramolecularly. In conclusion, we present a mechanism that dictates the direction of the phosphoryl group transfer within ArcB dimers and that enables the discrimination of the kinase and phosphatase activities of ArcB.
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Affiliation(s)
- Juan L Teran-Melo
- From the Departamento de Genética Molecular, Instituto de Fisiología Celular Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico
| | - Gabriela R Peña-Sandoval
- the Unidad Académica de Agricultura, Universidad Autónoma de Nayarit, 63190 Tepic, Nayarit, Mexico, and
| | - Hortencia Silva-Jimenez
- the Area de Oceanografía Química, Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, 22860 Ensenada, Baja California, Mexico
| | - Claudia Rodriguez
- From the Departamento de Genética Molecular, Instituto de Fisiología Celular Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico
| | - Adrián F Alvarez
- From the Departamento de Genética Molecular, Instituto de Fisiología Celular Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico
| | - Dimitris Georgellis
- From the Departamento de Genética Molecular, Instituto de Fisiología Celular Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico,
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18
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Wang FF, Cheng ST, Wu Y, Ren BZ, Qian W. A Bacterial Receptor PcrK Senses the Plant Hormone Cytokinin to Promote Adaptation to Oxidative Stress. Cell Rep 2018; 21:2940-2951. [PMID: 29212037 DOI: 10.1016/j.celrep.2017.11.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 09/18/2017] [Accepted: 11/03/2017] [Indexed: 12/19/2022] Open
Abstract
Recognition of the host plant is a prerequisite for infection by pathogenic bacteria. However, how bacterial cells sense plant-derived stimuli, especially chemicals that function in regulating plant development, remains completely unknown. Here, we have identified a membrane-bound histidine kinase of the phytopathogenic bacterium Xanthomonas campestris, PcrK, as a bacterial receptor that specifically detects the plant cytokinin 2-isopentenyladenine (2iP). 2iP binds to the extracytoplasmic region of PcrK to decrease its autokinase activity. Through a four-step phosphorelay, 2iP stimulation decreased the phosphorylation level of PcrR, the cognate response regulator of PcrK, to activate the phosphodiesterase activity of PcrR in degrading the second messenger 3',5'-cyclic diguanylic acid. 2iP perception by the PcrK-PcrR remarkably improves bacterial tolerance to oxidative stress by regulating the transcription of 56 genes, including the virulence-associated TonB-dependent receptor gene ctrA. Our results reveal an evolutionarily conserved, inter-kingdom signaling by which phytopathogenic bacteria intercept a plant hormone signal to promote adaptation to oxidative stress.
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Affiliation(s)
- Fang-Fang Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shou-Ting Cheng
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; School of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yao Wu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Bao-Zhen Ren
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; School of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Qian
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
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Abstract
This is a tale of how technology drove the discovery of the molecular basis for signal transduction in the initiation of sporulation in Bacillus subtilis and in bacterial two-component systems. It progresses from genetics to cloning and sequencing to biochemistry to structural biology to an understanding of how proteins evolve interaction specificity and to identification of interaction surfaces by statistical physics. This is about how the people in my laboratory accomplished this feat; without them little would have been done.
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Affiliation(s)
- James A Hoch
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037;
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20
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Stojanovski K, Ferrar T, Benisty H, Uschner F, Delgado J, Jimenez J, Solé C, de Nadal E, Klipp E, Posas F, Serrano L, Kiel C. Interaction Dynamics Determine Signaling and Output Pathway Responses. Cell Rep 2017; 19:136-149. [PMID: 28380353 DOI: 10.1016/j.celrep.2017.03.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 12/27/2016] [Accepted: 03/08/2017] [Indexed: 12/28/2022] Open
Abstract
The understanding of interaction dynamics in signaling pathways can shed light on pathway architecture and provide insights into targets for intervention. Here, we explored the relevance of kinetic rate constants of a key upstream osmosensor in the yeast high-osmolarity glycerol-mitogen-activated protein kinase (HOG-MAPK) pathway to signaling output responses. We created mutant pairs of the Sln1-Ypd1 complex interface that caused major compensating changes in the association (kon) and dissociation (koff) rate constants (kinetic perturbations) but only moderate changes in the overall complex affinity (Kd). Yeast cells carrying a Sln1-Ypd1 mutant pair with moderate increases in kon and koff displayed a lower threshold of HOG pathway activation than wild-type cells. Mutants with higher kon and koff rates gave rise to higher basal signaling and gene expression but impaired osmoadaptation. Thus, the kon and koff rates of the components in the Sln1 osmosensor determine proper signaling dynamics and osmoadaptation.
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Affiliation(s)
- Klement Stojanovski
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Tony Ferrar
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Hannah Benisty
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Friedemann Uschner
- Theoretical Biophysics, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Javier Delgado
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Javier Jimenez
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Carme Solé
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Eulalia de Nadal
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Edda Klipp
- Theoretical Biophysics, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Francesc Posas
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, 08003 Barcelona, Spain.
| | - Luis Serrano
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra, 08003 Barcelona, Spain; ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain.
| | - Christina Kiel
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra, 08003 Barcelona, Spain.
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21
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Russell JR, Cabeen MT, Wiggins PA, Paulsson J, Losick R. Noise in a phosphorelay drives stochastic entry into sporulation in Bacillus subtilis. EMBO J 2017; 36:2856-2869. [PMID: 28838935 DOI: 10.15252/embj.201796988] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/17/2017] [Accepted: 08/01/2017] [Indexed: 11/09/2022] Open
Abstract
Entry into sporulation in Bacillus subtilis is governed by a phosphorelay in which phosphoryl groups from a histidine kinase are successively transferred via relay proteins to the response regulator Spo0A. Spo0A~P, in turn, sets in motion events that lead to asymmetric division and activation of the cell-specific transcription factor σF, a hallmark for entry into sporulation. Here, we have used a microfluidics-based platform to investigate the activation of Spo0A and σF in individual cells held under constant, sporulation-inducing conditions. The principal conclusions were that: (i) activation of σF occurs with an approximately constant probability after adaptation to conditions of nutrient limitation; (ii) activation of σF is tightly correlated with, and preceded by, Spo0A~P reaching a high threshold level; (iii) activation of Spo0A takes place abruptly just prior to asymmetric division; and (iv) the primary source of noise in the activation of Spo0A is the phosphorelay. We propose that cells exhibit a constant probability of attaining a high threshold level of Spo0A~P due to fluctuations in the flux of phosphoryl groups through the phosphorelay.
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Affiliation(s)
- Jonathan R Russell
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Matthew T Cabeen
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Paul A Wiggins
- Departments of Physics, Bioengineering and Microbiology, University of Washington, Seattle, WA, USA
| | - Johan Paulsson
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Richard Losick
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
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22
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Foster CA, West AH. Use of restrained molecular dynamics to predict the conformations of phosphorylated receiver domains in two-component signaling systems. Proteins 2016; 85:155-176. [PMID: 27802580 PMCID: PMC5242315 DOI: 10.1002/prot.25207] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 10/22/2016] [Accepted: 10/25/2016] [Indexed: 01/22/2023]
Abstract
Two‐component signaling (TCS) is the primary means by which bacteria, as well as certain plants and fungi, respond to external stimuli. Signal transduction involves stimulus‐dependent autophosphorylation of a sensor histidine kinase and phosphoryl transfer to the receiver domain of a downstream response regulator. Phosphorylation acts as an allosteric switch, inducing structural and functional changes in the pathway's components. Due to their transient nature, phosphorylated receiver domains are challenging to characterize structurally. In this work, we provide a methodology for simulating receiver domain phosphorylation to predict conformations that are nearly identical to experimental structures. Using restrained molecular dynamics, phosphorylated conformations of receiver domains can be reliably sampled on nanosecond timescales. These simulations also provide data on conformational dynamics that can be used to identify regions of functional significance related to phosphorylation. We first validated this approach on several well‐characterized receiver domains and then used it to compare the upstream and downstream components of the fungal Sln1 phosphorelay. Our results demonstrate that this technique provides structural insight, obtained in the absence of crystallographic or NMR information, regarding phosphorylation‐induced conformational changes in receiver domains that regulate the output of their associated signaling pathway. To our knowledge, this is the first time such a protocol has been described that can be broadly applied to TCS proteins for predictive purposes. Proteins 2016; 85:155–176. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Clay A Foster
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
| | - Ann H West
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
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23
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Chaves AFA, Navarro MV, Castilho DG, Calado JCP, Conceição PM, Batista WL. A conserved dimorphism-regulating histidine kinase controls the dimorphic switching in Paracoccidioides brasiliensis. FEMS Yeast Res 2016; 16:fow047. [PMID: 27268997 DOI: 10.1093/femsyr/fow047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2016] [Indexed: 02/05/2023] Open
Abstract
Paracoccidioides brasiliensis and P. lutzii, thermally dimorphic fungi, are the causative agents of paracoccidioidomycosis (PCM). Paracoccidioides infection occurs when conidia or mycelium fragments are inhaled by the host, which causes the Paracoccidioides cells to transition to the yeast form. The development of disease requires conidia inside the host alveoli to differentiate into yeast cells in a temperature-dependent manner. We describe the presence of a two-component signal transduction system in P. brasiliensis, which we investigated by expression analysis of a hypothetical protein gene (PADG_07579) that showed high similarity with the dimorphism-regulating histidine kinase (DRK1) gene of Blastomyces dermatitidis and Histoplasma capsulatum This gene was sensitive to environmental redox changes, which was demonstrated by a dose-dependent decrease in transcript levels after peroxide stimulation and a subtler decrease in transcript levels after NO stimulation. Furthermore, the higher PbDRK1 levels after treatment with increasing NaCl concentrations suggest that this histidine kinase can play a role as osmosensing. In the mycelium-yeast (M→Y) transition, PbDRK1 mRNA expression increased 14-fold after 24 h incubation at 37°C, consistent with similar observations in other virulent fungi. These results demonstrate that the PbDRK1 gene is differentially expressed during the dimorphic M→Y transition. Finally, when P. brasiliensis mycelium cells were exposed to a histidine kinase inhibitor and incubated at 37°C, there was a delay in the dimorphic M→Y transition, suggesting that histidine kinases could be targets of interest for PCM therapy.
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Affiliation(s)
- Alison F A Chaves
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Unidade José Alencar, Street São Nicolau, nº210, 4º floor, São Paulo 04023-900, Brazil
| | - Marina V Navarro
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Unidade José Alencar, Street São Nicolau, nº210, 4º floor, São Paulo 04023-900, Brazil
| | - Daniele G Castilho
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Unidade José Alencar, Street São Nicolau, nº210, 4º floor, São Paulo 04023-900, Brazil
| | - Juliana C P Calado
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Unidade José Alencar, Street São Nicolau, nº210, 4º floor, São Paulo 04023-900, Brazil
| | - Palloma M Conceição
- Departamento de Ciências Farmacêuticas, Universidade Federal de São Paulo, Diadema 09913-030, São Paulo, Brazil
| | - Wagner L Batista
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Unidade José Alencar, Street São Nicolau, nº210, 4º floor, São Paulo 04023-900, Brazil Departamento de Ciências Farmacêuticas, Universidade Federal de São Paulo, Diadema 09913-030, São Paulo, Brazil
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24
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Abstract
How can changes in growth rate affect the regulatory networks behavior and the outcomes of cellular differentiation? We address this question by focusing on starvation response in sporulating Bacillus subtilis We show that the activity of sporulation master regulator Spo0A increases with decreasing cellular growth rate. Using a mathematical model of the phosphorelay-the network controlling Spo0A-we predict that this increase in Spo0A activity can be explained by the phosphorelay protein accumulation and lengthening of the period between chromosomal replication events caused by growth slowdown. As a result, only cells growing slower than a certain rate reach threshold Spo0A activity necessary for sporulation. This growth threshold model accurately predicts cell fates and explains the distribution of sporulation deferral times. We confirm our predictions experimentally and show that the concentration rather than activity of phosphorelay proteins is affected by the growth slowdown. We conclude that sensing the growth rates enables cells to indirectly detect starvation without the need for evaluating specific stress signals.
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Affiliation(s)
- Jatin Narula
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Anna Kuchina
- Division of Biological Sciences, UCSD, San Diego, CA, USA
| | - Fang Zhang
- Division of Biological Sciences, UCSD, San Diego, CA, USA
| | - Masaya Fujita
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Gürol M Süel
- Division of Biological Sciences, UCSD, San Diego, CA, USA
| | - Oleg A Igoshin
- Department of Bioengineering, Rice University, Houston, TX, USA
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25
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Abstract
The phosphorelay of Bacillus subtilis, a kinase cascade that activates master regulator Spo0A ~ P in response to starvation signals, is the core of a large network controlling the cell's decision to differentiate into sporulation and other phenotypes. This article reviews recent advances in understanding the origins and purposes of the complex dynamical behavior of the phosphorelay, which pulses with peaks of activity coordinated with the cell cycle. The transient imbalance in the expression of two critical genes caused by their strategic placement at opposing ends of the chromosome proved to be the key for this pulsed behavior. Feedback control loops in the phosphorelay use these pulses to implement a timer mechanism, which creates several windows of opportunity for phenotypic transitions over multiple generations. This strategy allows the cell to coordinate multiple differentiation programs in a decision process that fosters phenotypic diversity and adapts to current conditions.
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Affiliation(s)
- Daniel Schultz
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
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26
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Bobay BG, Thompson RJ, Milton DL, Cavanagh J. Chemical shift assignments and secondary structure prediction of the phosphorelay protein VanU from Vibrio anguillarum. Biomol NMR Assign 2014; 8:177-179. [PMID: 23604692 PMCID: PMC3770736 DOI: 10.1007/s12104-013-9478-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/09/2013] [Indexed: 06/02/2023]
Abstract
Vibrio anguillarum is a biofilm forming Gram-negative bacterium that survives prolonged periods in seawater and causes vibriosis in marine life. A quorum-sensing signal transduction pathway initiates biofilm formation in response to environmental stresses. The phosphotransferase protein VanU is the focal point of the quorum-sensing pathway and facilitates the regulation between independent phosphorelay systems that activate or repress biofilm formation. Here we report the (1)H, (13)C, and (15)N backbone and side chain resonance assignments and secondary structure prediction for VanU from V. anguillarum.
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Affiliation(s)
- Benjamin G Bobay
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, 27695, USA
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27
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Carabetta VJ, Tanner AW, Greco TM, Defrancesco M, Cristea IM, Dubnau D. A complex of YlbF, YmcA and YaaT regulates sporulation, competence and biofilm formation by accelerating the phosphorylation of Spo0A. Mol Microbiol 2013; 88:283-300. [PMID: 23490197 PMCID: PMC3781937 DOI: 10.1111/mmi.12186] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2013] [Indexed: 11/27/2022]
Abstract
Bacillus subtilis has adopted a bet-hedging strategy to ensure survival in changing environments. From a clonal population, numerous sub-populations can emerge, expressing different sets of genes that govern the developmental processes of sporulation, competence and biofilm formation. The master transcriptional regulator Spo0A controls the entry into all three fates and the production of the phosphorylated active form of Spo0A is precisely regulated via a phosphorelay, involving at least four proteins. Two proteins, YmcA and YlbF were previously shown to play an unidentified role in the regulation of biofilm formation, and in addition, YlbF was shown to regulate competence and sporulation. Using an unbiased proteomics screen, we demonstrate that YmcA and YlbF interact with a third protein, YaaT to form a tripartite complex. We show that all three proteins are required for proper establishment of the three above-mentioned developmental states. We show that the complex regulates the activity of Spo0A in vivo and, using in vitro reconstitution experiments, determine that they stimulate the phosphorelay, probably by interacting with Spo0F and Spo0B. We propose that the YmcA-YlbF-YaaT ternary complex is required to increase Spo0A~P levels above the thresholds needed to induce development.
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Affiliation(s)
- Valerie J. Carabetta
- Public Health Research Center at New Jersey Medical School, 225 Warren Street, Newark, NJ 07103
| | - Andrew W. Tanner
- Department of Microbiology and Molecular Genetics, New Jersey Medical School, 225 Warren Street, Newark NJ 07103
| | - Todd M. Greco
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Melissa Defrancesco
- Public Health Research Center at New Jersey Medical School, 225 Warren Street, Newark, NJ 07103
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - David Dubnau
- Public Health Research Center at New Jersey Medical School, 225 Warren Street, Newark, NJ 07103
- Department of Microbiology and Molecular Genetics, New Jersey Medical School, 225 Warren Street, Newark NJ 07103
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28
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Kim J. Phosphorylation of A-Type ARR to function as negative regulator of cytokinin signal transduction. Plant Signal Behav 2008; 3:348-50. [PMID: 19841668 PMCID: PMC2634280 DOI: 10.4161/psb.3.5.5375] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 12/04/2007] [Indexed: 05/08/2023]
Abstract
The plant hormone cytokinins regulate diverse aspects of plant growth and development. In Arabidopsis, a multi-step TCS system similar to bacterial and yeast TCS is used for cytokinin signaling. In a TCS system, a His sensor kinase perceives the signal by auto-phosphorylating on a His residue in response to an output signal, and the phosphate group is transferred to a conserved Asp residue in the receiver domain of the response regulator. The response regulator then modulates downstream signaling. Cytokinin multi-step TCS system utilizes an additional component, histidine-containing phosphotransfer domain protein (HPT) to transfer the phosphate group from a sensor kinase to a response regulator in the nucleus. The typical response regulators are classified into either type A or B. The type-B ARRs are transcription activators that act as positive regulators of cytokinin signaling, whereas most of the type-A ARRs are negative regulators of cytokinin signaling. Histidyl-aspartidyl phosphorelays are presumed to be essential for this cytokinin signal transduction in plants. Our studies have shown that ARR7, an A-type response regulator, negatively regulates cytokinin signaling in various aspects by acting as a transcriptional repressor and that the phosphorylation of ARR7 is required for these ARR7-regulated cytokinin-responses. Here I propose potential mechanisms by which the phosphorylation of ARRs is involved in regulating cytokinin- mediated gene expression, mainly based on biochemical and structural studies of bacterial response regulators. Protein-protein interaction and DNA-binding studies using the phosphorylated and the un-phosphorylated forms of the ARR proteins with their structural determination will provide molecular understanding of cytokinin-responsive gene regulation by ARRs.
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Affiliation(s)
- Jungmook Kim
- Department of Plant Biotechnology; Agricultural Plant Stress Research Center, and Biotechnology Research Institute; Chonnam National University; Buk-Gu, Gwangju, Korea
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29
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Hutchison CE, Kieber JJ. Signaling via Histidine-Containing Phosphotransfer Proteins in Arabidopsis. Plant Signal Behav 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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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Affiliation(s)
- Claire E Hutchison
- Department of Biology; University of North Carolina; Chapel Hill, North Carolina USA
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30
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Wang L, Grau R, Perego M, Hoch JA. A novel histidine kinase inhibitor regulating development in Bacillus subtilis. Genes Dev 1997; 11:2569-79. [PMID: 9334321 PMCID: PMC316564 DOI: 10.1101/gad.11.19.2569] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1997] [Accepted: 08/05/1997] [Indexed: 02/05/2023]
Abstract
Kinase A is the sensor histidine kinase responsible for processing postexponential phase information and providing phosphate input to the phosphorelay that activates developmental transcription via phosphorylated Spo0A. A protein inhibitor, KipI, of kinase A was discovered encoded in an operon of genes of unknown function but regulated by the availability of fixed nitrogen. KipI is a potent inhibitor of the autophosphorylation reaction of kinase A but does not inhibit phosphate transfer to the Spo0F response regulator once kinase A is phosphorylated. KipI is an inhibitor of the catalytic domain of kinase A affecting the ATP/ADP reactions and not the phosphotransferase functions of this domain. The inhibitory activity of KipI is counteracted by the product of another gene in the operon, KipA. This protein may bind to KipI, preventing its function as an inhibitor of kinase A. KipI may be the first representative of a new class of signal transduction inhibitors that function by direct interaction with the catalytic domain of histidine kinases to counteract signals influencing the "sensor" domain of such kinases. This inhibitor represents yet another way by which the phosphorelay signal transduction system is affected by negative regulators under the control of metabolic, environmental, or cell cycle influences antithetical to the initiation of developmental transcription.
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Affiliation(s)
- L Wang
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
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