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Gan Q, Fan C. Orthogonal Translation for Site-Specific Installation of Post-translational Modifications. Chem Rev 2024; 124:2805-2838. [PMID: 38373737 PMCID: PMC11230630 DOI: 10.1021/acs.chemrev.3c00850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Post-translational modifications (PTMs) endow proteins with new properties to respond to environmental changes or growth needs. With the development of advanced proteomics techniques, hundreds of distinct types of PTMs have been observed in a wide range of proteins from bacteria, archaea, and eukarya. To identify the roles of these PTMs, scientists have applied various approaches. However, high dynamics, low stoichiometry, and crosstalk between PTMs make it almost impossible to obtain homogeneously modified proteins for characterization of the site-specific effect of individual PTM on target proteins. To solve this problem, the genetic code expansion (GCE) strategy has been introduced into the field of PTM studies. Instead of modifying proteins after translation, GCE incorporates modified amino acids into proteins during translation, thus generating site-specifically modified proteins at target positions. In this review, we summarize the development of GCE systems for orthogonal translation for site-specific installation of PTMs.
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Affiliation(s)
- Qinglei Gan
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Chenguang Fan
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, Arkansas 72701, United States
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2
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Alves de Castro P, Figueiredo Pinzan C, Dos Reis TF, Valero C, Van Rhijn N, Menegatti C, de Freitas Migliorini IL, Bromley M, Fleming AB, Traynor AM, Sarikaya-Bayram Ö, Bayram Ö, Malavazi I, Ebel F, Barbosa JCJ, Fill T, Pupo MT, Goldman GH. Aspergillus fumigatus mitogen-activated protein kinase MpkA is involved in gliotoxin production and self-protection. Nat Commun 2024; 15:33. [PMID: 38167253 PMCID: PMC10762094 DOI: 10.1038/s41467-023-44329-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
Aspergillus fumigatus is a saprophytic fungus that can cause a variety of human diseases known as aspergillosis. Mycotoxin gliotoxin (GT) production is important for its virulence and must be tightly regulated to avoid excess production and toxicity to the fungus. GT self-protection by GliT oxidoreductase and GtmA methyltransferase activities is related to the subcellular localization of these enzymes and how GT can be sequestered from the cytoplasm to avoid increased cell damage. Here, we show that GliT:GFP and GtmA:GFP are localized in the cytoplasm and in vacuoles during GT production. The Mitogen-Activated Protein kinase MpkA is essential for GT production and self-protection, interacts physically with GliT and GtmA and it is necessary for their regulation and subsequent presence in the vacuoles. The sensor histidine kinase SlnASln1 is important for modulation of MpkA phosphorylation. Our work emphasizes the importance of MpkA and compartmentalization of cellular events for GT production and self-defense.
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Affiliation(s)
- Patrícia Alves de Castro
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Camila Figueiredo Pinzan
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Thaila Fernanda Dos Reis
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Clara Valero
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Norman Van Rhijn
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Carla Menegatti
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | | | - Michael Bromley
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Alastair B Fleming
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Aimee M Traynor
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | | | - Özgür Bayram
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland.
| | - Iran Malavazi
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
| | - Frank Ebel
- Institut für Infektionsmedizin und Zoonosen, Medizinische Fakultät, LMU, 80539, München, Germany
| | | | - Taícia Fill
- Instituto de Química, Universidade Estadual de Campinas, Campinas, Brazil
| | - Monica Tallarico Pupo
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Gustavo H Goldman
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
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3
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Identification and molecular evolution of the La and LARP genes in 16 plant species: A focus on the Gossypium hirsutum. Int J Biol Macromol 2022; 224:1101-1117. [DOI: 10.1016/j.ijbiomac.2022.10.195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 10/12/2022] [Accepted: 10/20/2022] [Indexed: 11/05/2022]
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4
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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.
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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
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Silva MA, Salgueiro CA. Multistep Signaling in Nature: A Close-Up of Geobacter Chemotaxis Sensing. Int J Mol Sci 2021; 22:ijms22169034. [PMID: 34445739 PMCID: PMC8396549 DOI: 10.3390/ijms22169034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/30/2021] [Accepted: 08/09/2021] [Indexed: 11/23/2022] Open
Abstract
Environmental changes trigger the continuous adaptation of bacteria to ensure their survival. This is possible through a variety of signal transduction pathways involving chemoreceptors known as methyl-accepting chemotaxis proteins (MCP) that allow the microorganisms to redirect their mobility towards favorable environments. MCP are two-component regulatory (or signal transduction) systems (TCS) formed by a sensor and a response regulator domain. These domains synchronize transient protein phosphorylation and dephosphorylation events to convert the stimuli into an appropriate cellular response. In this review, the variability of TCS domains and the most common signaling mechanisms are highlighted. This is followed by the description of the overall cellular topology, classification and mechanisms of MCP. Finally, the structural and functional properties of a new family of MCP found in Geobacter sulfurreducens are revisited. This bacterium has a diverse repertoire of chemosensory systems, which represents a striking example of a survival mechanism in challenging environments. Two G. sulfurreducens MCP—GSU0582 and GSU0935—are members of a new family of chemotaxis sensor proteins containing a periplasmic PAS-like sensor domain with a c-type heme. Interestingly, the cellular location of this domain opens new routes to the understanding of the redox potential sensing signaling transduction pathways.
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Affiliation(s)
- Marta A. Silva
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal;
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
| | - Carlos A. Salgueiro
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal;
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
- Correspondence:
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Cai E, Sun S, Deng Y, Huang P, Sun X, Wang Y, Chang C, Jiang Z. Histidine Kinase Sln1 and cAMP/PKA Signaling Pathways Antagonistically Regulate Sporisorium scitamineum Mating and Virulence via Transcription Factor Prf1. J Fungi (Basel) 2021; 7:jof7080610. [PMID: 34436149 PMCID: PMC8397173 DOI: 10.3390/jof7080610] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/16/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
Many prokaryotes and eukaryotes utilize two-component signaling pathways to counter environmental stress and regulate virulence genes associated with infection. In this study, we identified and characterized a conserved histidine kinase (SsSln1), which is the sensor of the two-component system of Sln1-Ypd1-Ssk1 in Sporisorium scitamineum. SsSln1 null mutant exhibited enhanced mating and virulence capabilities in S. scitamineum, which is opposite to what has been reported in Candida albicans. Further investigations revealed that the deletion of SsSLN1 enhanced SsHog1 phosphorylation and nuclear localization and thus promoted S. scitamineum mating. Interestingly, SsSln1 and cAMP/PKA signaling pathways antagonistically regulated the transcription of pheromone-responsive transcription factor SsPrf1, for regulating S. scitamineum mating and virulence. In short, the study depicts a novel mechanism in which the cross-talk between SsSln1 and cAMP/PKA pathways antagonistically regulates mating and virulence by balancing the transcription of the SsPRF1 gene in S. scitamineum.
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Affiliation(s)
- Enping Cai
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Integrate Microbiology Research Center, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China;
| | - Shuquan Sun
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Environmental Monitoring and Remediation Engineering Technology Research Center, School of Environmental Engineering, Yellow River Conservancy Technical Institute, Kaifeng 475004, China
| | - Yizhen Deng
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Integrate Microbiology Research Center, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China;
| | - Peishen Huang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Integrate Microbiology Research Center, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China;
| | - Xian Sun
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Integrate Microbiology Research Center, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China;
| | - Yuting Wang
- Integrate Microbiology Research Center, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China;
| | - Changqing Chang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Integrate Microbiology Research Center, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China;
- Correspondence: (C.C.); (Z.J.); Tel.: +86-020-757-3225 (C.C.); +86-020-3860-4779 (Z.J.)
| | - Zide Jiang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (E.C.); (S.S.); (Y.D.); (P.H.); (X.S.)
- Correspondence: (C.C.); (Z.J.); Tel.: +86-020-757-3225 (C.C.); +86-020-3860-4779 (Z.J.)
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7
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Putative Membrane Receptors Contribute to Activation and Efficient Signaling of Mitogen-Activated Protein Kinase Cascades during Adaptation of Aspergillus fumigatus to Different Stressors and Carbon Sources. mSphere 2020; 5:5/5/e00818-20. [PMID: 32938702 PMCID: PMC7494837 DOI: 10.1128/msphere.00818-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The high-osmolarity glycerol (HOG) response pathway is a multifunctional signal transduction pathway that specifically transmits ambient osmotic signals. Saccharomyces cerevisiae Hog1p has two upstream signaling branches, the sensor histidine kinase Sln1p and the receptor Sho1p. The Sho1p branch includes two other proteins, the Msb2p mucin and Opy2p. Aspergillus fumigatus is the leading cause of pulmonary fungal diseases. Here, we investigated the roles played by A. fumigatus SlnASln1p, ShoASho1p, MsbAMsb2p, and OpyAOpy2p putative homologues during the activation of the mitogen-activated protein kinase (MAPK) HOG pathway. The shoA, msbA, and opyA singly and doubly null mutants are important for the cell wall integrity (CWI) pathway, oxidative stress, and virulence as assessed by a Galleria mellonella model. Genetic interactions of ShoA, MsbA, and OpyA are also important for proper activation of the SakAHog1p and MpkASlt2 cascade and the response to osmotic and cell wall stresses. Comparative label-free quantitative proteomics analysis of the singly null mutants with the wild-type strain upon caspofungin exposure indicates that the absence of ShoA, MsbA, and OpyA affects the osmotic stress response, carbohydrate metabolism, and protein degradation. The putative receptor mutants showed altered trehalose and glycogen accumulation, suggesting a role for ShoA, MsbA, and OpyA in sugar storage. Protein kinase A activity was also decreased in these mutants. We also observed genetic interactions between SlnA, ShoA, MsbA, and OpyA, suggesting that both branches are important for activation of the HOG/CWI pathways. Our results help in the understanding of the activation and modulation of the HOG and CWI pathways in this important fungal pathogen.IMPORTANCE Aspergillus fumigatus is an important human-pathogenic fungal species that is responsible for a high incidence of infections in immunocompromised individuals. A. fumigatus high-osmolarity glycerol (HOG) and cell wall integrity pathways are important for the adaptation to different forms of environmental adversity such as osmotic and oxidative stresses, nutrient limitations, high temperatures, and other chemical and mechanical stresses that may be produced by the host immune system and antifungal drugs. Little is known about how these pathways are activated in this fungal pathogen. Here, we characterize four A. fumigatus putative homologues that are important for the activation of the yeast HOG pathway. A. fumigatus SlnASln1p, ShoASho1p, MsbAMsb2p, and OpyAOpy2p are genetically interacting and are essential for the activation of the HOG and cell wall integrity pathways. Our results contribute to the understanding of A. fumigatus adaptation to the host environment.
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New Insights into Multistep-Phosphorelay (MSP)/ Two-Component System (TCS) Regulation: Are Plants and Bacteria that Different? PLANTS 2019; 8:plants8120590. [PMID: 31835810 PMCID: PMC6963811 DOI: 10.3390/plants8120590] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 11/27/2019] [Accepted: 12/07/2019] [Indexed: 12/12/2022]
Abstract
The Arabidopsis multistep-phosphorelay (MSP) is a signaling mechanism based on a phosphorelay that involves three different types of proteins: Histidine kinases, phosphotransfer proteins, and response regulators. Its bacterial equivalent, the two-component system (TCS), is the most predominant device for signal transduction in prokaryotes. The TCS has been extensively studied and is thus generally well-understood. In contrast, the MSP in plants was first described in 1993. Although great advances have been made, MSP is far from being completely comprehended. Focusing on the model organism Arabidopsis thaliana, this review summarized recent studies that have revealed many similarities with bacterial TCSs regarding how TCS/MSP signaling is regulated by protein phosphorylation and dephosphorylation, protein degradation, and dimerization. Thus, comparison with better-understood bacterial systems might be relevant for an improved study of the Arabidopsis MSP.
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Branscum KM, Menon SK, Foster CA, West AH. Insights revealed by the co-crystal structure of the Saccharomyces cerevisiae histidine phosphotransfer protein Ypd1 and the receiver domain of its downstream response regulator Ssk1. Protein Sci 2019; 28:2099-2111. [PMID: 31642125 PMCID: PMC6863705 DOI: 10.1002/pro.3755] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/21/2019] [Accepted: 10/21/2019] [Indexed: 01/28/2023]
Abstract
Two‐component signaling systems are the primary means by which bacteria, archaea, and certain plants and fungi react to their environments. The model yeast, Saccharomyces cerevisiae, uses the Sln1 signaling pathway to respond to hyperosmotic stress. This pathway contains a hybrid histidine kinase (Sln1) that autophosphorylates and transfers a phosphoryl group to its own receiver domain (R1). The phosphoryl group is then transferred to a histidine phosphotransfer protein (Ypd1) that finally passes it to the receiver domain (R2) of a downstream response regulator (Ssk1). Under normal conditions, Ssk1 is constitutively and preferentially phosphorylated in the phosphorelay. Upon detecting hyperosmotic stress, Ssk1 rapidly dephosphorylates and activates the high‐osmolarity glycerol (HOG) pathway, initiating a response. Despite their distinct physiological roles, both Sln1 and Ssk1 bind to Ypd1 at a common docking site. Co‐crystal structures of response regulators in complex with their phosphorelay partners are scarce, leaving many mechanistic and structural details uncharacterized for systems like the Sln1 pathway. In this work, we present the co‐crystal structure of Ypd1 and a near wild‐type variant of the receiver domain of Ssk1 (Ssk1‐R2‐W638A) at a resolution of 2.80 Å. Our structural analyses of Ypd1‐receiver domain complexes, biochemical determination of binding affinities for Ssk1‐R2 variants, in silico free energy estimates, and sequence comparisons reveal distinctive electrostatic properties of the Ypd1/Ssk1‐R2‐W638A complex that may provide insight into the regulation of the Sln1 pathway as a function of dynamic osmolyte concentration.
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Affiliation(s)
- Katie M Branscum
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
| | - Smita K Menon
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
| | - Clay A Foster
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma.,Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
| | - Ann H West
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
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Abbas S, Hwang J, Kim H, Chae SA, Kim JW, Mehboob S, Ahn A, Han OH, Ha HY. Enzyme-Inspired Formulation of the Electrolyte for Stable and Efficient Vanadium Redox Flow Batteries at High Temperatures. ACS APPLIED MATERIALS & INTERFACES 2019; 11:26842-26853. [PMID: 31268664 DOI: 10.1021/acsami.9b06790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Histidine, inspired by vanadium bromoperoxidase enzyme, has been applied as a homogeneous electrocatalyst to the positive electrolyte of vanadium redox flow battery (VRFB) to improve the performance and stability of VRFB at elevated temperatures. The histidine-containing electrolyte is found to significantly improve the performance of VRFB in terms of thermal stability estimated by the remaining amount of VO2+ in the electrolyte (61 vs 43% of a pristine one), energy efficiency at a high current density of 150 mA cm-2 (78.7 vs 71.2%), and capacity retention (73.2 vs 27.7%) at 60 °C. The mechanism of the catalytic functions of histidine with the chemical species in the electrolyte has been investigated for the first time by multinuclear NMR spectroscopy and first-principles calculations. The analyzed data reveal that histidine improves the kinetics of both charge and discharge reactions through different affinity toward the reactants and products as well as suppresses the precipitation of VO2+ by impeding the polymerization of vanadium ions. These findings are in good agreement with the improved chemical and electrochemical performance of the histidine-containing VRFB. Our results show a new type of chemical/electrochemical mechanism in the improved redox flow battery performance that may be essential in a new research arena for better performance of electrochemical systems.
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Affiliation(s)
- Saleem Abbas
- Center for Energy Storage Research , Korea Institute of Science and Technology (KIST) , 14-gil 5, Hwarang-ro , Seongbuk-gu, Seoul 02792 , Republic of Korea
- Division of Energy & Environmental Engineering , Korea University of Science & Technology (UST)-KIST School , 217 Gajeong-ro , Yuseong-gu, Daejeon 34113 , Republic of Korea
| | - Jinyeon Hwang
- Center for Energy Storage Research , Korea Institute of Science and Technology (KIST) , 14-gil 5, Hwarang-ro , Seongbuk-gu, Seoul 02792 , Republic of Korea
| | - Heejin Kim
- Electron Microscopy Center , Korea Basic Science Institute , Daejeon 34133 , Republic of Korea
| | - Seen Ae Chae
- Western Seoul Center , Korea Basic Science Institute (KBSI) , Seoul 03759 , Republic of Korea
| | - Ji Won Kim
- Western Seoul Center , Korea Basic Science Institute (KBSI) , Seoul 03759 , Republic of Korea
| | - Sheeraz Mehboob
- Center for Energy Storage Research , Korea Institute of Science and Technology (KIST) , 14-gil 5, Hwarang-ro , Seongbuk-gu, Seoul 02792 , Republic of Korea
- Division of Energy & Environmental Engineering , Korea University of Science & Technology (UST)-KIST School , 217 Gajeong-ro , Yuseong-gu, Daejeon 34113 , Republic of Korea
| | - Ahreum Ahn
- Center for Computational Science and Engineering , Korea Institute of Science and Technology Information , Daejeon 34141 , Republic of Korea
| | - Oc Hee Han
- Western Seoul Center , Korea Basic Science Institute (KBSI) , Seoul 03759 , Republic of Korea
- Graduate School of Analytical Science & Technology , Chungnam National University , Daejeon 34134 , Republic of Korea
- Department of Chemistry & Nano Science , Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Heung Yong Ha
- Center for Energy Storage Research , Korea Institute of Science and Technology (KIST) , 14-gil 5, Hwarang-ro , Seongbuk-gu, Seoul 02792 , Republic of Korea
- Division of Energy & Environmental Engineering , Korea University of Science & Technology (UST)-KIST School , 217 Gajeong-ro , Yuseong-gu, Daejeon 34113 , Republic of Korea
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Hu Y, Weng Y, Jiang B, Li X, Zhang X, Zhao B, Wu Q, Liang Z, Zhang L, Zhang Y. Isolation and identification of phosphorylated lysine peptides by retention time difference combining dimethyl labeling strategy. Sci China Chem 2019. [DOI: 10.1007/s11426-018-9433-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Liang Q, Li B, Wang J, Ren P, Yao L, Meng Y, Si E, Shang X, Wang H. PGPBS, a mitogen-activated protein kinase kinase, is required for vegetative differentiation, cell wall integrity, and pathogenicity of the barley leaf stripe fungus Pyrenophora graminea. Gene 2019; 696:95-104. [PMID: 30779945 DOI: 10.1016/j.gene.2019.02.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 01/07/2019] [Accepted: 02/01/2019] [Indexed: 01/23/2023]
Abstract
The high-osmolarity glycerol (HOG) signaling pathway regulates the adaptation of fungi to environmental stressors. The mitogen-activated protein kinase kinase (MAPKK) PBS2 of Saccharomyces cerevisiae serves as a scaffold protein in the HOG pathway. We characterized the pgpbs gene of Pyrenophora graminea, which encodes a MAPKK that is 56% orthologous to PBS2 of S. cerevisiae. A cloning technique based on homology was applied to amplify the pgpbs gene. Specific silent mutations then were generated in pgpbs. We evaluated the potential roles of PGPBS in the osmotic response, vegetative differentiation, cell wall integrity, drug resistance, and pathogenicity. Our findings indicated that the pgpbs coding region comprises 2075 base pairs and encodes a protein of 676 amino acids. Mutants deficient in pgpbs expression had significant reductions in vegetative growth and were sensitive to calcofluor white (CFW), an inhibitor of cell wall synthesis. Mutants also lost pathogenicity and were sensitive to an osmotic stress-inducing medium containing NaCl and sorbitol. Moreover, mutants had increased resistance to the dicarboximide fungicide iprodione and the triazole fungicide tebuconazole. These findings suggest that pgpbs is involved in the osmotic and ionic stress responses, vegetative differentiation, cell wall integrity, virulence, and tolerance to iprodione and tebuconazole. We expect that our findings will help elucidate the pathogenesis of barley leaf stripe and will inform strategies for breeding resistance to this disease.
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Affiliation(s)
- Qianqian Liang
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Engeering Laboratory of Application Mycology, Hexi University, Zhangye, China
| | - Baochun Li
- Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China; College of Life Sciences and Technology, Gansu Agricultural University, Lanzhou, China
| | - Junchen Wang
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China
| | - Panrong Ren
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China
| | - Lirong Yao
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China
| | - Yaxiong Meng
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China
| | - Erjing Si
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China
| | - Xunwu Shang
- Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China
| | - Huajun Wang
- College of Agronomy, Gansu Agriculture University, Lanzhou, China; Gansu Provincial Key Lab of Aridland Crop Science/Gansu Key Lab of Crop Improvement & Germplasm Enhancement, Lanzhou, China.
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13
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Kennedy EN, Hebdon SD, Menon SK, Foster CA, Copeland DM, Xu Q, Janiak-Spens F, West AH. Role of the highly conserved G68 residue in the yeast phosphorelay protein Ypd1: implications for interactions between histidine phosphotransfer (HPt) and response regulator proteins. BMC BIOCHEMISTRY 2019; 20:1. [PMID: 30665347 PMCID: PMC6341664 DOI: 10.1186/s12858-019-0104-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 01/07/2019] [Indexed: 11/29/2022]
Abstract
Background Many bacteria and certain eukaryotes utilize multi-step His-to-Asp phosphorelays for adaptive responses to their extracellular environments. Histidine phosphotransfer (HPt) proteins function as key components of these pathways. HPt proteins are genetically diverse, but share a common tertiary fold with conserved residues near the active site. A surface-exposed glycine at the H + 4 position relative to the phosphorylatable histidine is found in a significant number of annotated HPt protein sequences. Previous reports demonstrated that substitutions at this position result in diminished phosphotransfer activity between HPt proteins and their cognate signaling partners. Results We report the analysis of partner binding interactions and phosphotransfer activity of the prototypical HPt protein Ypd1 from Saccharomyces cerevisiae using a set of H + 4 (G68) substituted proteins. Substitutions at this position with large, hydrophobic, or charged amino acids nearly abolished phospho-acceptance from the receiver domain of its upstream signaling partner, Sln1 (Sln1-R1). An in vitro binding assay indicated that G68 substitutions caused only modest decreases in affinity between Ypd1 and Sln1-R1, and these differences did not appear to be large enough to account for the observed decrease in phosphotransfer activity. The crystal structure of one of these H + 4 mutants, Ypd1-G68Q, which exhibited a diminished ability to participate in phosphotransfer, shows a similar overall structure to that of wild-type. Molecular modelling suggests that the highly conserved active site residues within the receiver domain of Sln1 must undergo rearrangement to accommodate larger H + 4 substitutions in Ypd1. Conclusions Phosphotransfer reactions require precise arrangement of active site elements to align the donor-acceptor atoms and stabilize the transition state during the reaction. Any changes likely result in an inability to form a viable transition state during phosphotransfer. Our data suggest that the high degree of evolutionary conservation of residues with small side chains at the H + 4 position in HPt proteins is required for optimal activity and that the presence of larger residues at the H + 4 position would cause alterations in the positioning of active site residues in the partner response regulator. Electronic supplementary material The online version of this article (10.1186/s12858-019-0104-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Emily N Kennedy
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA.,Present Address: University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Skyler D Hebdon
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA
| | - Smita K Menon
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA
| | - Clay A Foster
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA.,Present Address: University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Daniel M Copeland
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA.,Present Address: Pacira Pharmaceuticals, San Diego, CA, 92121, USA
| | - Qingping Xu
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA.,Present Address: GMCA at Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Fabiola Janiak-Spens
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA
| | - Ann H West
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA.
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14
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Liu LJ, Wang WM, Yao L, Meng FJ, Sun YM, Xu H, Xu ZY, Li Q, Zhao CQ, Han LB. Reinvestigation of the Substitutions Reaction of Stereogenic Phosphoryl Compounds: Stereochemistry, Mechanism, and Applications. J Org Chem 2017; 82:11990-12002. [DOI: 10.1021/acs.joc.7b01326] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Li-Juan Liu
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Wei-Min Wang
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Lan Yao
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Fan-Jie Meng
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Yong-Ming Sun
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Hao Xu
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Zhong-Yuan Xu
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Qiang Li
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Chang-Qiu Zhao
- College
of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252059, China
| | - Li-Biao Han
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
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15
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Kothamachu VB, Feliu E, Cardelli L, Soyer OS. Unlimited multistability and Boolean logic in microbial signalling. J R Soc Interface 2016; 12:20150234. [PMID: 26040599 PMCID: PMC4528588 DOI: 10.1098/rsif.2015.0234] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The ability to map environmental signals onto distinct internal physiological states or programmes is critical for single-celled microbes. A crucial systems dynamics feature underpinning such ability is multistability. While unlimited multistability is known to arise from multi-site phosphorylation seen in the signalling networks of eukaryotic cells, a similarly universal mechanism has not been identified in microbial signalling systems. These systems are generally known as two-component systems comprising histidine kinase (HK) receptors and response regulator proteins engaging in phosphotransfer reactions. We develop a mathematical framework for analysing microbial systems with multi-domain HK receptors known as hybrid and unorthodox HKs. We show that these systems embed a simple core network that exhibits multistability, thereby unveiling a novel biochemical mechanism for multistability. We further prove that sharing of downstream components allows a system with n multi-domain hybrid HKs to attain 3n steady states. We find that such systems, when sensing distinct signals, can readily implement Boolean logic functions on these signals. Using two experimentally studied examples of two-component systems implementing hybrid HKs, we show that bistability and implementation of logic functions are possible under biologically feasible reaction rates. Furthermore, we show that all sequenced microbial genomes contain significant numbers of hybrid and unorthodox HKs, and some genomes have a larger fraction of these proteins compared with regular HKs. Microbial cells are thus theoretically unbounded in mapping distinct environmental signals onto distinct physiological states and perform complex computations on them. These findings facilitate the understanding of natural two-component systems and allow their engineering through synthetic biology.
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Affiliation(s)
- Varun B Kothamachu
- Systems Biology Program, College of Engineering, Computing and Mathematics, University of Exeter, Exeter, UK
| | - Elisenda Feliu
- Department of Mathematical Sciences, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Luca Cardelli
- Microsoft Research Cambridge, 7 JJ Thomson Avenue, Cambridge CB3 0FB, UK
| | - Orkun S Soyer
- School of Life Sciences, University of Warwick, Coventry, UK
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16
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Chanclud E, Kisiala A, Emery NRJ, Chalvon V, Ducasse A, Romiti-Michel C, Gravot A, Kroj T, Morel JB. Cytokinin Production by the Rice Blast Fungus Is a Pivotal Requirement for Full Virulence. PLoS Pathog 2016; 12:e1005457. [PMID: 26900703 PMCID: PMC4765853 DOI: 10.1371/journal.ppat.1005457] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/25/2016] [Indexed: 12/22/2022] Open
Abstract
Plants produce cytokinin (CK) hormones for controlling key developmental processes like source/sink distribution, cell division or programmed cell-death. Some plant pathogens have been shown to produce CKs but the function of this mimicry production by non-tumor inducing pathogens, has yet to be established. Here we identify a gene required for CK biosynthesis, CKS1, in the rice blast fungus Magnaporthe oryzae. The fungal-secreted CKs are likely perceived by the plant during infection since the transcriptional regulation of rice CK-responsive genes is altered in plants infected by the mutants in which CKS1 gene was deleted. Although cks1 mutants showed normal in vitro growth and development, they were severely affected for in planta growth and virulence. Moreover, we showed that the cks1 mutant triggered enhanced induction of plant defenses as manifested by an elevated oxidative burst and expression of defense-related markers. In addition, the contents of sugars and key amino acids for fungal growth were altered in and around the infection site by the cks1 mutant in a different manner than by the control strain. These results suggest that fungal-derived CKs are key effectors required for dampening host defenses and affecting sugar and amino acid distribution in and around the infection site.
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Affiliation(s)
- Emilie Chanclud
- Université Montpellier, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France
| | - Anna Kisiala
- Biology Department, Trent University, Peterborough, Ontario, Canada
- Department of Plant Genetics, Physiology and Biotechnology, University of Technology and Life Sciences, Bydgoszcz, Poland
| | - Neil R. J Emery
- Biology Department, Trent University, Peterborough, Ontario, Canada
| | | | | | | | | | - Thomas Kroj
- INRA, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France
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17
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Jacob S, Foster AJ, Yemelin A, Thines E. High osmolarity glycerol (HOG) signalling in Magnaporthe oryzae: Identification of MoYPD1 and its role in osmoregulation, fungicide action, and pathogenicity. Fungal Biol 2015; 119:580-94. [DOI: 10.1016/j.funbio.2015.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 02/20/2015] [Accepted: 03/04/2015] [Indexed: 01/22/2023]
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18
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Dexter JP, Xu P, Gunawardena J, McClean MN. Robust network structure of the Sln1-Ypd1-Ssk1 three-component phospho-relay prevents unintended activation of the HOG MAPK pathway in Saccharomyces cerevisiae. BMC SYSTEMS BIOLOGY 2015; 9:17. [PMID: 25888817 PMCID: PMC4377207 DOI: 10.1186/s12918-015-0158-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 02/26/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND The yeast Saccharomyces cerevisiae relies on the high-osmolarity glycerol (HOG) signaling pathway to respond to increases in external osmolarity. The HOG pathway is rapidly activated under conditions of elevated osmolarity and regulates transcriptional and metabolic changes within the cell. Under normal growth conditions, however, a three-component phospho-relay consisting of the histidine kinase Sln1, the transfer protein Ypd1, and the response regulator Ssk1 represses HOG pathway activity by phosphorylation of Ssk1. This inhibition of the HOG pathway is essential for cellular fitness in normal osmolarity. Nevertheless, the extent to and mechanisms by which inhibition is robust to fluctuations in the concentrations of the phospho-relay components has received little attention. RESULTS We established that the Sln1-Ypd1-Ssk1 phospho-relay is robust-it is able to maintain inhibition of the HOG pathway even after significant changes in the levels of its three components. We then developed a biochemically realistic mathematical model of the phospho-relay, which suggested that robustness is due to buffering by a large excess pool of Ypd1. We confirmed experimentally that depletion of the Ypd1 pool results in inappropriate activation of the HOG pathway. CONCLUSIONS We identified buffering by an intermediate component in excess as a novel mechanism through which a phospho-relay can achieve robustness. This buffering requires multiple components and is therefore unavailable to two-component systems, suggesting one important advantage of multi-component relays.
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Affiliation(s)
- Joseph P Dexter
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
- Department of Chemistry, Princeton University, Princeton, NJ, USA.
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA.
| | - Ping Xu
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
| | | | - Megan N McClean
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA.
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19
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Osmosensing and osmoregulation in unicellular eukaryotes. World J Microbiol Biotechnol 2015; 31:435-43. [DOI: 10.1007/s11274-015-1811-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 01/27/2015] [Indexed: 10/24/2022]
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20
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Paluch P, Pawlak T, Oszajca M, Lasocha W, Potrzebowski MJ. Fine refinement of solid state structure of racemic form of phospho-tyrosine employing NMR Crystallography approach. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 65:2-11. [PMID: 25240460 DOI: 10.1016/j.ssnmr.2014.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/29/2014] [Indexed: 05/25/2023]
Abstract
We present step by step facets important in NMR Crystallography strategy employing O-phospho-dl-tyrosine as model sample. The significance of three major techniques being components of this approach: solid state NMR (SS NMR), X-ray diffraction of powdered sample (PXRD) and theoretical calculations (Gauge Invariant Projector Augmented Wave; GIPAW) is discussed. Each experimental technique provides different set of structural constraints. From the PXRD measurement the size of the unit cell, space group and roughly refined molecular structure are established. SS NMR provides information about content of crystallographic asymmetric unit, local geometry, molecular motion in the crystal lattice and hydrogen bonding pattern. GIPAW calculations are employed for validation of quality of elucidation and fine refinement of structure. Crystal and molecular structure of O-phospho-dl-tyrosine solved by NMR Crystallography is deposited at Cambridge Crystallographic Data Center under number CCDC 1005924.
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Affiliation(s)
- Piotr Paluch
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, PL-90-363 Lodz, Poland
| | - Tomasz Pawlak
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, PL-90-363 Lodz, Poland
| | - Marcin Oszajca
- Jerzy Haber Institute of Catalysis and Surface Chemistry, PAS, Niezapominajek 8, 30-239 Krakow, Poland
| | - Wieslaw Lasocha
- Jerzy Haber Institute of Catalysis and Surface Chemistry, PAS, Niezapominajek 8, 30-239 Krakow, Poland; Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland
| | - Marek J Potrzebowski
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, PL-90-363 Lodz, Poland.
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21
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Phosphorelays provide tunable signal processing capabilities for the cell. PLoS Comput Biol 2013; 9:e1003322. [PMID: 24244132 PMCID: PMC3820541 DOI: 10.1371/journal.pcbi.1003322] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 09/23/2013] [Indexed: 01/19/2023] Open
Abstract
Achieving a complete understanding of cellular signal transduction requires deciphering the relation between structural and biochemical features of a signaling system and the shape of the signal-response relationship it embeds. Using explicit analytical expressions and numerical simulations, we present here this relation for four-layered phosphorelays, which are signaling systems that are ubiquitous in prokaryotes and also found in lower eukaryotes and plants. We derive an analytical expression that relates the shape of the signal-response relationship in a relay to the kinetic rates of forward, reverse phosphorylation and hydrolysis reactions. This reveals a set of mathematical conditions which, when satisfied, dictate the shape of the signal-response relationship. We find that a specific topology also observed in nature can satisfy these conditions in such a way to allow plasticity among hyperbolic and sigmoidal signal-response relationships. Particularly, the shape of the signal-response relationship of this relay topology can be tuned by altering kinetic rates and total protein levels at different parts of the relay. These findings provide an important step towards predicting response dynamics of phosphorelays, and the nature of subsequent physiological responses that they mediate, solely from topological features and few composite measurements; measuring the ratio of reverse and forward phosphorylation rate constants could be sufficient to determine the shape of the signal-response relationship the relay exhibits. Furthermore, they highlight the potential ways in which selective pressures on signal processing could have played a role in the evolution of the observed structural and biochemical characteristic in phosphorelays. Two-component phosphorelays constitute the key signaling pathways in all prokaryotes, lower eukaryotes, and plants, where they underline diverse physiological responses such as virulence, cell-cycle progression and sporulation. Despite such prevalence, our understanding of the dynamics and function of these systems remains incomplete. In particular, it is not clear why all phosphorelays studied to date embed a four-layer architecture and how their dynamics could relate to phenotypic variability in the resulting responses. Here, we use analytical approaches and numerical simulations to analyze all possible phosphorelay topologies of length four and embedding reverse phosphorylation. We find that only two topologies can embed both hyperbolic and sigmoidal signal-response relationships, and that one of these can underlie high noise (i.e. phenotypic variability) in population responses. All of the remaining topologies are either non-functional or can embed only a hyperbolic signal-response relationship. Using analytical solutions of relay dynamics, we find that reverse phosphorylation from the third layer, a topological featured commonly observed in nature, is a necessary condition for sigmoidal signal-response relationship.
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22
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Kushwaha HR, Singla-Pareek SL, Pareek A. Putative osmosensor--OsHK3b--a histidine kinase protein from rice shows high structural conservation with its ortholog AtHK1 from Arabidopsis. J Biomol Struct Dyn 2013; 32:1318-32. [PMID: 23869567 PMCID: PMC4017273 DOI: 10.1080/07391102.2013.818576] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 06/19/2013] [Indexed: 11/10/2022]
Abstract
Prokaryotes and eukaryotes respond to various environmental stimuli using the two-component system (TCS). Essentially, it consists of membrane-bound histidine kinase (HK) which senses the stimuli and further transfers the signal to the response regulator, which in turn, regulates expression of various target genes. Recently, sequence-based genome wide analysis has been carried out in Arabidopsis and rice to identify all the putative members of TCS family. One of the members of this family i.e. AtHK1, (a putative osmosensor, hybrid-type sensory histidine kinase) is known to interact with AtHPt1 (phosphotransfer proteins) in Arabidopsis. Based on predicted rice interactome network (PRIN), the ortholog of AtHK1 in rice, OsHK3b, was found to be interacting with OsHPt2. The analysis of amino acid sequence of AtHK1 showed the presence of transmitter domain (TD) and receiver domain (RD), while OsHK3b showed presence of three conserved domains namely CHASE (signaling domain), TD, and RD. In order to elaborate on structural details of functional domains of hybrid-type HK and phosphotransfer proteins in both these genera, we have modeled them using homology modeling approach. The structural motifs present in various functional domains of the orthologous proteins were found to be highly conserved. Binding analysis of the RD domain of these sensory proteins in Arabidopsis and rice revealed the role of various residues such as histidine in HPt protein which are essential for their interaction.
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Affiliation(s)
- Hemant Ritturaj Kushwaha
- Synthetic Biology and Biofuel Group, International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Sneh Lata Singla-Pareek
- Plant Molecular Biology, International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Ashwani Pareek
- Stress Physiology and Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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23
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Tomar N, Choudhury O, Chakrabarty A, De RK. An integrated pathway system modeling of Saccharomyces cerevisiae HOG pathway: a Petri net based approach. Mol Biol Rep 2012; 40:1103-25. [PMID: 23086300 DOI: 10.1007/s11033-012-2153-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 10/03/2012] [Indexed: 12/22/2022]
Abstract
Biochemical networks comprise many diverse components and interactions between them. It has intracellular signaling, metabolic and gene regulatory pathways which are highly integrated and whose responses are elicited by extracellular actions. Previous modeling techniques mostly consider each pathway independently without focusing on the interrelation of these which actually functions as a single system. In this paper, we propose an approach of modeling an integrated pathway using an event-driven modeling tool, i.e., Petri nets (PNs). PNs have the ability to simulate the dynamics of the system with high levels of accuracy. The integrated set of signaling, regulatory and metabolic reactions involved in Saccharomyces cerevisiae's HOG pathway has been collected from the literature. The kinetic parameter values have been used for transition firings. The dynamics of the system has been simulated and the concentrations of major biological species over time have been observed. The phenotypic characteristics of the integrated system have been investigated under two conditions, viz., under the absence and presence of osmotic pressure. The results have been validated favorably with the existing experimental results. We have also compared our study with the study of idFBA (Lee et al., PLoS Comput Biol 4:e1000-e1086, 2008) and pointed out the differences between both studies. We have simulated and monitored concentrations of multiple biological entities over time and also incorporated feedback inhibition by Ptp2 which has not been included in the idFBA study. We have concluded that our study is the first to the best of our knowledge to model signaling, metabolic and regulatory events in an integrated form through PN model framework. This study is useful in computational simulation of system dynamics for integrated pathways as there are growing evidences that the malfunctioning of the interplay among these pathways is associated with disease.
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Affiliation(s)
- Namrata Tomar
- Machine Intelligence Unit, Indian Statistical Institute, 203 B. T. Road, Kolkata, 700108, India.
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24
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Suescún-Bolívar LP, Iglesias-Prieto R, Thomé PE. Induction of glycerol synthesis and release in cultured Symbiodinium. PLoS One 2012; 7:e47182. [PMID: 23071753 PMCID: PMC3469543 DOI: 10.1371/journal.pone.0047182] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 09/10/2012] [Indexed: 11/19/2022] Open
Abstract
Background Symbiotic dinoflagellates transfer a substantial amount of their photosynthetic products to their animal hosts. This amount has been estimated to represent up to 90% of the photosynthetically fixed carbon and can satisfy in some instances the full respiratory requirements of the host. Although in several cnidarian-dinoflagellate symbioses glycerol is the primary photosynthetic product translocated to the host, the mechanism for its production and release has not been demonstrated conclusively. Principal Findings Using Symbiodinium cells in culture we were able to reproduce the synthesis and release of glycerol in vitro by employing an inductor for glycerol synthesis, osmotic up-shocks. Photosynthetic parameters and fluorescence analysis of photosystem II showed that the inductive conditions did not have a negative effect on photosynthetic performance, suggesting that the capacity for carbon fixation by the cells was not compromised. The demand for glycerol production required to attain osmotic balance increased the expression of ribulose 1,5-bisphosphate and of glycerol 3-phosphate dehydrogenase, possibly competing with the flux of fixed carbon necessary for protein synthesis. In longer exposures of cultured Symbiodinium cells to high osmolarity, the response was analogous to photoacclimation, reducing the excitation pressure over photosystem II, suggesting that Symbiodinium cells perceived the stress as an increase in light. The induced synthesis of glycerol resulted in a reduction of growth rates. Conclusions Our results favor a hypothetical mechanism of a signaling event involving a pressure sensor that may induce the flux of carbon (glycerol) from the symbiotic algae to the animal host, and strongly suggest that carbon limitation may be a key factor modulating the population of symbionts within the host.
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Affiliation(s)
- Luis P. Suescún-Bolívar
- Unidad Académica de Sistemas Arrecifales Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Roberto Iglesias-Prieto
- Unidad Académica de Sistemas Arrecifales Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Patricia E. Thomé
- Unidad Académica de Sistemas Arrecifales Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mexico City, Mexico
- * E-mail:
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25
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Abstract
An appropriate response and adaptation to hyperosmolarity, i.e., an external osmolarity that is higher than the physiological range, can be a matter of life or death for all cells. It is especially important for free-living organisms such as the yeast Saccharomyces cerevisiae. When exposed to hyperosmotic stress, the yeast initiates a complex adaptive program that includes temporary arrest of cell-cycle progression, adjustment of transcription and translation patterns, and the synthesis and retention of the compatible osmolyte glycerol. These adaptive responses are mostly governed by the high osmolarity glycerol (HOG) pathway, which is composed of membrane-associated osmosensors, an intracellular signaling pathway whose core is the Hog1 MAP kinase (MAPK) cascade, and cytoplasmic and nuclear effector functions. The entire pathway is conserved in diverse fungal species, while the Hog1 MAPK cascade is conserved even in higher eukaryotes including humans. This conservation is illustrated by the fact that the mammalian stress-responsive p38 MAPK can rescue the osmosensitivity of hog1Δ mutations in response to hyperosmotic challenge. As the HOG pathway is one of the best-understood eukaryotic signal transduction pathways, it is useful not only as a model for analysis of osmostress responses, but also as a model for mathematical analysis of signal transduction pathways. In this review, we have summarized the current understanding of both the upstream signaling mechanism and the downstream adaptive responses to hyperosmotic stress in yeast.
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Affiliation(s)
- Haruo Saito
- Division of Molecular Cell Signaling, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8638, Japan, and
| | - Francesc Posas
- Cell Signaling Unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, E-08003 Barcelona, Spain
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26
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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]
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27
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de Nadal E, Posas F. Elongating under Stress. GENETICS RESEARCH INTERNATIONAL 2011; 2011:326286. [PMID: 22567351 PMCID: PMC3335722 DOI: 10.4061/2011/326286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 07/06/2011] [Indexed: 01/13/2023]
Abstract
In response to extracellular stimuli, mitogen-activated protein kinases (MAPKs) modulate gene expression to maximize cell survival. Exposure of yeast to high osmolarity results in activation of the p38-related MAPK Hog1, which plays a key role in reprogramming the gene expression pattern required for cell survival upon osmostress. Hog1 not only regulates initiation but also modulates other steps of the transcription process. Recent work indicates that other yeast signalling MAPKs such as Mpk1 modulate transcriptional elongation in response to cell wall stress. Similarly, mammalian MAPKs have also been found associated to coding regions of stress-responsive genes. In this paper, significant progress in MAPK-regulated events that occur during the transcriptional elongation step is summarized, and future directions are discussed. We expect that the principles learned from these studies will provide a new understanding of the regulation of gene expression by signalling kinases.
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Affiliation(s)
- Eulàlia de Nadal
- Cell Signaling Unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), C/ Doctor Aiguader 88, 08003 Barcelona, Spain
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28
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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.
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Affiliation(s)
- Qingyu Sun
- Department of Chemistry, University of California, Riverside, 900 University Ave, Riverside, CA 92521, USA
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29
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A two-component histidine kinase, MoSLN1, is required for cell wall integrity and pathogenicity of the rice blast fungus, Magnaporthe oryzae. Curr Genet 2010; 56:517-28. [DOI: 10.1007/s00294-010-0319-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 08/22/2010] [Accepted: 09/01/2010] [Indexed: 10/19/2022]
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30
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Csikász-Nagy A, Cardelli L, Soyer OS. Response dynamics of phosphorelays suggest their potential utility in cell signalling. J R Soc Interface 2010; 8:480-8. [PMID: 20702449 PMCID: PMC3061117 DOI: 10.1098/rsif.2010.0336] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Phosphorelays are extended two-component signalling systems found in diverse bacteria, lower eukaryotes and plants. Only few of these systems are characterized, and we still lack a full understanding of their signalling abilities. Here, we aim to achieve a global understanding of phosphorelay signalling and its dynamical properties. We develop a generic model, allowing us to systematically analyse response dynamics under different assumptions. Using this model, we find that the steady-state concentration of phosphorylated protein at the final layer of a phosphorelay is a linearly increasing, but eventually saturating function of the input. In contrast, the intermediate layers can display ultrasensitivity. We find that such ultrasensitivity is a direct result of the phosphorelay biochemistry; shuttling of a single phosphate group from the first to the last layer. The response dynamics of the phosphorelay results in tolerance of cross-talk, especially when it occurs as cross-deactivation. Further, it leads to a high signal-to-noise ratio for the final layer. We find that a relay length of four, which is most commonly observed, acts as a saturating point for these dynamic properties. These findings suggest that phosphorelays could act as a mechanism to reduce noise and effects of cross-talk on the final layer of the relay and enforce its input–response relation to be linear. In addition, our analysis suggests that middle layers of phosphorelays could embed thresholds. We discuss the consequence of these findings in relation to why cells might use phosphorelays along with enzymatic kinase cascades.
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Affiliation(s)
- Attila Csikász-Nagy
- Microsoft Research-University of Trento Centre for Computational and Systems Biology (CoSBi), Povo (Trento), Italy.
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31
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Kino T, Segars JH, Chrousos GP. The Guanine Nucleotide Exchange Factor Brx: A Link between Osmotic Stress, Inflammation and Organ Physiology and Pathophysiology. Expert Rev Endocrinol Metab 2010; 5:603-614. [PMID: 21037977 PMCID: PMC2964845 DOI: 10.1586/eem.10.3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Dehydration, and consequent intracellular hyperosmolarity, is a major challenge to land organisms, as it is associated with extraction of water from cells and disturbance of global cellular function. Organisms have thus developed a highly conserved regulatory mechanism that transduces the hyperosmolarity signal from the cell surface to the cell nucleus and adjusts the expression of cellular osmolarity-regulating genes. We recently found that the Rho-type guanine nucleotide exchange factor Brx, or AKAP13, is essential for osmotic stress-stimulated expression of nuclear factor of activated T-cells 5 (NFAT5), a key transcription factor of intracellular osmolarity. It accomplishes this by first attracting cJun kinase (JNK)-interacting protein (JIP) 4 and then coupling activated Rho-type small G-proteins to cascade components of the p38 MAPK signaling pathway, ultimately activating NFAT5. We describe the potential implications of osmotic stress and Brx activation in organ physiology and pathophysiology and connect activation of this system to key human homeostatic states.
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Affiliation(s)
- Tomoshige Kino
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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32
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Stewart RC. Protein histidine kinases: assembly of active sites and their regulation in signaling pathways. Curr Opin Microbiol 2010; 13:133-41. [PMID: 20117042 PMCID: PMC2847664 DOI: 10.1016/j.mib.2009.12.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 12/23/2009] [Accepted: 12/29/2009] [Indexed: 10/19/2022]
Abstract
Protein histidine kinases (PHKs) function in Two Component Signaling pathways utilized extensively by bacteria and archaea. Many PHKs participate in three distinct, but interrelated signaling reactions: autophoshorylation, phosphotransfer (to a partner Response Regulator (RR) protein), and dephosphorylation of this RR. Detailed biochemical and structural characterization of several PHKs has revealed how the domains of these proteins can interact to assemble the three active sites that promote the necessary chemistry and how these domain interactions might be regulated in response to sensory input: the relative orientation of helices in the PHK dimerization domain can reorient, via cogwheeling (rotation) and kinking (bending), to effect changes in PHK activities that probably involve sequestration/release of the PHK catalytic domain by the dimerization domain.
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Affiliation(s)
- Richard C Stewart
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD 20742, USA.
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33
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34
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Kaserer AO, Andi B, Cook PF, West AH. Effects of osmolytes on the SLN1-YPD1-SSK1 phosphorelay system from Saccharomyces cerevisiae. Biochemistry 2009; 48:8044-50. [PMID: 19618914 DOI: 10.1021/bi900886g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The multistep His-Asp phosphorelay system in Saccharomyces cerevisiae allows cells to adapt to osmotic, oxidative, and other environmental stresses. The pathway consists of a hybrid histidine kinase SLN1, a histidine-containing phosphotransfer (HPt) protein YPD1, and two response regulator proteins, SSK1 and SKN7. Under nonosmotic stress conditions, the SLN1 sensor kinase is active, and phosphoryl groups are shuttled through YPD1 to SSK1, therefore maintaining the response regulator protein in a constitutively phosphorylated state. The cellular response to hyperosmotic stress involves rapid efflux of water and changes in intracellular ion and osmolyte concentration. In this study, we examined the individual and combined effects of NaCl and glycerol on phosphotransfer rates within the SLN1-YPD1-SSK1 phosphorelay. The results show that the combined effects of glycerol and NaCl on the phosphotransfer reaction rates are different from the individual effects of glycerol and NaCl. The combinatory effect is likely more representative of the in vivo changes that occur during hyperosmotic stress. In addition, the effect of osmolyte concentration on the half-life of the phosphorylated SSK1 receiver domain in the presence/absence of YPD1 was evaluated. Our findings demonstrate that increasing osmolyte concentrations negatively affect the YPD1 x SSK1-P interaction, thereby facilitating dephosphorylation of SSK1 and activating the HOG1 MAP kinase cascade. In contrast, at the highest osmolyte concentrations, reflective of the osmoadaptation phase of the signaling pathway, the kinetics of the phosphorelay favor production of SSK1-P and inhibition of the HOG1 pathway.
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Affiliation(s)
- Alla O Kaserer
- Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, Oklahoma 73019, USA
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35
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Abstract
For many years, oxidative thiol modifications in cytosolic proteins were largely disregarded as in vitro artifacts, and considered unlikely to play significant roles within the reducing environment of the cell. Recent developments in in vivo thiol trapping technology combined with mass spectrometric analysis have now provided convincing evidence that thiol-based redox switches are used as molecular tools in many proteins to regulate their activity in response to reactive oxygen and nitrogen species. Reversible oxidative thiol modifications have been found to modulate the function of proteins involved in many different pathways, starting from gene transcription, translation and protein folding, to metabolism, signal transduction, and ultimately apoptosis. This review will focus on three well-characterized eukaryotic proteins that use thiol-based redox switches to influence gene transcription, metabolism, and signal transduction. The transcription factor Yap1p is a good illustration of how oxidative modifications affect the function of a protein without changing its activity. We use glyeraldehyde-3-phosphate dehydrogenase to demonstrate how thiol modification of an active site cysteine re-routes metabolic pathways and converts a metabolic enzyme into a pro-apoptotic factor. Finally, we introduce the redox-sensitive protein tyrosine phosphatase PTP1B to illustrate that reversibility is one of the fundamental aspects of redox-regulation.
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Affiliation(s)
- Nicolas Brandes
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
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36
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Boyle PM, Silver PA. Harnessing nature's toolbox: regulatory elements for synthetic biology. J R Soc Interface 2009; 6 Suppl 4:S535-46. [PMID: 19324675 DOI: 10.1098/rsif.2008.0521.focus] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Synthetic biologists seek to engineer complex biological systems composed of modular elements. Achieving higher complexity in engineered biological organisms will require manipulating numerous systems of biological regulation: transcription; RNA interactions; protein signalling; and metabolic fluxes, among others. Exploiting the natural modularity at each level of biological regulation will promote the development of standardized tools for designing biological systems.
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Affiliation(s)
- Patrick M Boyle
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
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37
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Cytokinin signaling during root development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:1-48. [PMID: 19584010 DOI: 10.1016/s1937-6448(09)76001-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cytokinin class of phytohormones regulates division and differentiation of plant cells. They are perceived and signaled by a phosphorelay mechanism similar to those observed in prokaryotes. Research into the components of phosphorelay had previously been marred by genetic redundancy. However, recent studies have addressed this with the creation of high-order mutants. In addition, several new elements regulating cytokinin signaling have been identified. This has uncovered many roles in diverse developmental and physiological processes. In this review, we look at these processes specifically in the context of root development. We focus on the formation and maintenance of the root apical meristem, primary and secondary vascular development, lateral root emergence and development, and root nodulation. We believe that the root is an ideal organ with which to investigate cytokinin signaling in a wider context.
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38
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Abstract
Two-component signal transduction based on phosphotransfer from a histidine protein kinase to a response regulator protein is a prevalent strategy for coupling environmental stimuli to adaptive responses in bacteria. In both histidine kinases and response regulators, modular domains with conserved structures and biochemical activities adopt different conformational states in the presence of stimuli or upon phosphorylation, enabling a diverse array of regulatory mechanisms based on inhibitory and/or activating protein-protein interactions imparted by different domain arrangements. This review summarizes some of the recent structural work that has provided insight into the functioning of bacterial histidine kinases and response regulators. Particular emphasis is placed on identifying features that are expected to be conserved among different two-component proteins from those that are expected to differ, with the goal of defining the extent to which knowledge of previously characterized two-component proteins can be applied to newly discovered systems.
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Affiliation(s)
- Rong Gao
- Center for Advanced Biotechnology and Medicine, Department of Biochemistry, UMDNJ-Robert Wood Johnson Medical School and Howard Hughes Medical Institute, Piscataway, New Jersey 08854-5627
| | - Ann M. Stock
- Center for Advanced Biotechnology and Medicine, Department of Biochemistry, UMDNJ-Robert Wood Johnson Medical School and Howard Hughes Medical Institute, Piscataway, New Jersey 08854-5627
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39
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Glycolytic enzyme GAPDH promotes peroxide stress signaling through multistep phosphorelay to a MAPK cascade. Mol Cell 2008; 30:108-13. [PMID: 18406331 DOI: 10.1016/j.molcel.2008.01.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 11/28/2007] [Accepted: 01/25/2008] [Indexed: 10/22/2022]
Abstract
Phosphorelay signaling of environmental stimuli by two-component systems is prevailing in bacteria and also utilized by fungi and plants. In the fission yeast Schizosaccharomyces pombe, peroxide stress signals are transmitted from the Mak2/3 sensor kinases to the Mpr1 histidine-containing phosphotransfer (HPt) protein and finally to the Mcs4 response regulator, which activates a MAP kinase cascade. Here we show that, unexpectedly, the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) physically associates with the Mcs4 response regulator and stress-responsive MAP kinase kinase kinases (MAPKKKs). In response to H2O2 stress, Cys-152 of the Tdh1 GAPDH is transiently oxidized, which enhances the association of Tdh1 with Mcs4. Furthermore, Tdh1 is essential for the interaction between the Mpr1 HPt protein and the Mcs4 response regulator and thus for phosphorelay signaling. These results demonstrate that the glycolytic enzyme GAPDH plays an essential role in the phosphorelay signaling, where its redox-sensitive cysteine residue may provide additional input signals.
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40
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Klein BS, Tebbets B. Dimorphism and virulence in fungi. Curr Opin Microbiol 2007; 10:314-9. [PMID: 17719267 PMCID: PMC3412142 DOI: 10.1016/j.mib.2007.04.002] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Accepted: 04/23/2007] [Indexed: 11/27/2022]
Abstract
The signature feature of systemic dimorphic fungi - a family of six primary fungal pathogens of humans - is a temperature-induced phase transition. These fungi grow as a mold in soil at ambient temperature and convert to yeast after infectious spores are inhaled into the lungs of a mammalian host. Seminal work 20 years ago established that a temperature-induced phase transition from mold to yeast is required for virulence. Several yeast-phase specific genes, identified one-by-one and studied by reverse genetics, have revealed mechanisms by which the phase transition promotes disease pathogenesis. Transcriptional profiling of microarrays built with genomic elements of Histoplasma capsulatum and ESTs of Paracoccidioides brasiliensis that represent partial genomes has identified 500 genes and 328 genes, respectively, that are differentially expressed upon the phase transition. The genomes of most of the dimorphic fungi are now in varying stages of being sequenced. The creation of additional microarrays and the application of new reverse genetic tools promise fresh insight into genes and mechanisms that regulate pathogenesis and morphogenesis. The use of insertional mutagenesis by Agrobacterium has uncovered a hybrid histidine kinase that regulates dimorphism and pathogenicity in Blastomyces dermatitidis and H. capsulatum. Two-component signaling appears to be a common strategy for model and pathogenic fungi to sense and respond to environmental stresses.
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Affiliation(s)
- Bruce S Klein
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
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41
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Tan H, Janiak-Spens F, West AH. Functional characterization of the phosphorelay protein Mpr1p from Schizosaccharomyces pombe. FEMS Yeast Res 2007; 7:912-21. [PMID: 17559414 DOI: 10.1111/j.1567-1364.2007.00260.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Histidine-containing phosphotransfer (HPt) proteins play an essential role in multistep histidine-aspartate phosphorelay signal transduction systems in prokaryotes and eukaryotes. The putative HPt protein in Schizosaccharomyces pombe, Mpr1p (also known as Spy1p), is a 295 amino acid protein that appears to be composed of more than one functional domain. The amino acid sequence of the N-terminal region of Mpr1p lacks homology to other known proteins, whereas the C-terminal domain is predicted to have structural similarity to the Ypd1p HPt protein from Saccharomyces cerevisiae. This study provides both in vitro and in vivo evidence that the C-terminal domain of Mpr1p indeed functions as an HPt protein in shuttling phosphoryl groups from one response regulator domain to another. Furthermore, we find that various deletions of the N-terminal region diminish both the phosphotransfer activity of Mpr1p and its affinity for response regulator domains, suggesting a possible role for the N-terminal domain in HPt-response regulator domain interactions.
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Affiliation(s)
- Hui Tan
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
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42
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Jelić D, Mildner B, Kostrun S, Nujić K, Verbanac D, Culić O, Antolović R, Brandt W. Homology modeling of human Fyn kinase structure: discovery of rosmarinic acid as a new Fyn kinase inhibitor and in silico study of its possible binding modes. J Med Chem 2007; 50:1090-100. [PMID: 17315853 DOI: 10.1021/jm0607202] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tyrosine phosphorylation represents a unique signaling process that controls metabolic pathways, cell activation, growth and differentiation, membrane transport, apoptosis, neural, and other functions. We present here the three-dimensional structure of Fyn tyrosine kinase, a Src-family enzyme involved in T-cell receptor signal transduction. The structure of Fyn was modeled for homology using the Sybyl-Composer suite of programs for modeling. Procheck and Prosa II programs showed the high quality of the obtained three-dimensional model. Rosmarinic acid, a secondary metabolite of herbal plants, was discovered as a new Fyn kinase inhibitor using immunochemical and in silico methods. Two possible binding modes of rosmarinic acid were evaluated here, i.e., near to or in the ATP-binding site of kinase domain of Fyn. Enzyme kinetic experiments revealed that Fyn is inhibited by a linear-mixed noncompetitive mechanism of inhibition by rosmarinic acid. This indicates that rosmarinic acid binds to the second "non-ATP" binding site of the Fyn tyrosine kinase.
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Affiliation(s)
- Dubravko Jelić
- GlaxoSmithKline Research Centre Zagreb, Prilaz baruna Filipovića 29, 10000 Zagreb,
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43
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Arribas-Bosacoma R, Kim SK, Ferrer-Orta C, Blanco AG, Pereira PJ, Gomis-Rüth FX, Wanner BL, Coll M, Solà M. The X-ray crystal structures of two constitutively active mutants of the Escherichia coli PhoB receiver domain give insights into activation. J Mol Biol 2007; 366:626-41. [PMID: 17182055 PMCID: PMC1855202 DOI: 10.1016/j.jmb.2006.11.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 11/07/2006] [Accepted: 11/09/2006] [Indexed: 11/22/2022]
Abstract
The PhoR/PhoB two-component system is a key regulatory protein network enabling Escherichia coli to respond to inorganic phosphate (Pi) starvation conditions by turning on Pho regulon genes for more efficient Pi uptake and use of alternative phosphorus sources. Under environmental Pi depletion, the response regulator (RR) component, PhoB, is phosphorylated at the receiver domain (RD), a process that requires Mg(2+) bound at the active site. Phosphorylation of the RD relieves the inhibition of the PhoB effector domain (ED), a DNA-binding region that binds to Pho regulon promoters to activate transcription. The molecular details of the activation are proposed to involve dimerization of the RD and a conformational change in the RD detected by the ED. The structure of the PhoB RD shows a symmetrical interaction involving alpha1, loop beta5alpha5 and N terminus of alpha5 elements, also seen in the complex of PhoB RD with Mg(2+), in which helix alpha4 highly increases its flexibility. PhoB RD in complex with Mg(2+) and BeF(3) (an emulator of the phosphate moiety) undergoes a dramatic conformational change on helix alpha4 and shows another interaction involving alpha4, beta5 and alpha5 segments. We have selected a series of constitutively active PhoB mutants (PhoB(CA)) that are able to turn on the Pho regulon promoters in the absence phosphorylation and, as they cannot be inactivated, should therefore mimic the active RD state of PhoB and its functional oligomerisation. We have analysed the PhoB(CA) RD crystal structures of two such mutants, Asp53Ala/Tyr102Cys and Asp10Ala/Asp53Glu. Interestingly, both mutants reproduce the homodimeric arrangement through the symmetric interface encountered in the unbound and magnesium-bound wild-type PhoB RD structures. Besides, the mutant RD structures show a modified active site organization as well as changes at helix alpha4 that correlate with repositioning of surrounding residues, like the active-site events indicator Trp54, putatively redifining the interaction with the ED in the full-length protein.
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Affiliation(s)
- Raquel Arribas-Bosacoma
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
| | - Soo-Ki Kim
- Department of Biological Sciences; Purdue University; West Lafayette; Indiana 47907 USA
| | - Cristina Ferrer-Orta
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
| | - Alexandre G. Blanco
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
| | - Pedro J.B. Pereira
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
| | - F. Xavier Gomis-Rüth
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
| | - Barry L. Wanner
- Department of Biological Sciences; Purdue University; West Lafayette; Indiana 47907 USA
| | - Miquel Coll
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
| | - Maria Solà
- Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain, and IRB - Parc Científic de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain
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Menon V, Li D, Chauhan N, Rajnarayanan R, Dubrovska A, West AH, Calderone R. Functional studies of the Ssk1p response regulator protein of Candida albicans as determined by phenotypic analysis of receiver domain point mutants. Mol Microbiol 2006; 62:997-1013. [PMID: 17038117 DOI: 10.1111/j.1365-2958.2006.05438.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Candida albicans response regulator protein Ssk1p regulates oxidant adaptation through the MAPK HOG1 pathway. Deletion mutants lacking SSK1 are oxidant sensitive in vitro and are killed more than wild-type (WT) cells by human neutrophils. Furthermore, the mutants are avirulent in an invasive murine model, and unable to adhere to human esophageal cells. Transcriptional profiling has indicated that approximately 25% of all changes occur in genes encoding cell wall and stress adaptation functions. In this study, we have investigated the role of amino acid residues in the Ssk1p receiver (or regulatory) domain by constructing point mutants at positions D556 (putative site of protein phosphorylation) and D513 (putative role in divalent metal binding, phosphorylation and conformational switching). For each point mutant, their sensitivity to a variety of oxidant stress conditions was assessed and correlated with in vitro phosphorylation of each Ssk1p receiver domain, phosphorylation of the Hog1p MAP kinase, and translocation to the nucleus. We show that a D556N mutant is sensitive to 5 mM H(2)O(2) or t-butyl hydroperoxide, similar to a gene knock-out ssk1 mutant, even though Hog1p is phosphorylated in the D556N mutant. To resolve this apparent paradox, we also demonstrate that Hog1p translocation to the nucleus in the D556N mutant is significantly reduced compared with WT cells (CAF2-1). In a second point mutant, D513 was changed to a lysine residue (D513K). This mutant had WT levels of resistance to peroxide, but in comparison to WT cells and the D556N mutant, morphogenesis (yeast to hyphae transition) was inhibited in 10% serum or in M-199 medium at 37 degrees C. In the D513K point mutant, constitutive phosphorylation of Hog1p was observed, suggesting that a non-conservative change (D513K) traps Ssk1p in an active conformation and therefore constitutive Hog1p phosphorylation. The inhibition of morphogenesis in D513K is related to a downregulation of the transcription factors of morphogenesis, EFG1 and CPH1. Another non-conserved point mutant (D556R) was also constructed and phenotypically was like the D513K mutant. The receiver domains of the D556N and the D513K mutants could not be appreciably phosphorylated in vitro indicating that constitutive activation of Hog1p occurs in vivo due to the inability of Ssk1p to be phosphorylated at least in the D513K mutant. We speculate that the non-conservative changes described above in Ssk1p response regulator may cause conformational changes in the Ssk1p that account for phenotype differences compared with the D556N mutant that are also Hog-independent.
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Affiliation(s)
- Veena Menon
- Georgetown University Medical Center, Department of Microbiology and Immunology, 3900 Reservoir Road, NW, Washington, DC 20057, USA
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Olejniczak S, Napora P, Gajda J, Ciesielski W, Potrzebowski MJ. 31P double-quantum solid-state NMR study of phosphoroorganic compounds with (O)P-O-P-(O), (S)P-O-P(S) and (S)P-S-P(O) unit. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2006; 30:141-9. [PMID: 16949260 DOI: 10.1016/j.ssnmr.2006.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 07/03/2006] [Accepted: 07/17/2006] [Indexed: 05/11/2023]
Abstract
In this work we have tested applicability of the commonly used double quantum recoupling sequence POST-C7 to study of (31)P-(31)P geometrical constraints for phosphoroorganic model compounds with different chemical shift anisotropy (CSA) and distinct molecular dynamics in the crystal lattice. Our results clearly show that even with large CSA, POST-C7 gives good efficiency of (31)P double-quantum excitations. Moreover, large amplitude molecular motion only slightly disturb (31)P build-up curve. Chi(2) error analysis is used for verification of values and orientations of chemical shift tensors (CST) parameters employed for simulation of POST-C7 buildup curves.
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Affiliation(s)
- Sebastian Olejniczak
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź, Poland
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Affiliation(s)
- Robert B Bourret
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA.
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Affiliation(s)
- W Wallace Cleland
- Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA.
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Bishopp A, Mähönen AP, Helariutta Y. Signs of change: hormone receptors that regulate plant development. Development 2006; 133:1857-69. [PMID: 16651539 DOI: 10.1242/dev.02359] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hormonal signalling plays a pivotal role in almost every aspect of plant development, and of high priority has been to identify the receptors that perceive these hormones. In the past seven months, the receptors for the plant hormones auxin, gibberellins and abscisic acid have been identified. These join the receptors that have previously been identified for ethylene,brassinosteroids and cytokinins. This review therefore comes at an exciting time for plant developmental biology, as the new findings shed light on our current understanding of the structure and function of the various hormone receptors, their related signalling pathways and their role in regulating plant development.
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Affiliation(s)
- Anthony Bishopp
- Plant Molecular Biology Laboratory, Institute of Biotechnology, POB 56, FI-00014, University of Helsinki, Finland
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Sugawara H, Yamaya T, Sakakibara H. Crystallization and preliminary X-ray diffraction study of the histidine-containing phosphotransfer protein ZmHP1 from maize. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:366-8. [PMID: 16511042 PMCID: PMC1952433 DOI: 10.1107/s1744309105006846] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Accepted: 03/04/2005] [Indexed: 11/11/2022]
Abstract
In histidine-aspartate phosphorelays (two-component systems) involved in plant-hormone signalling, histidine-containing phosphotransfer (HPt) proteins mediate the transfer of a phosphoryl group from the sensory histidine kinase to the response regulator. The maize HPt protein ZmHP1 has been crystallized. Although ZmHP1 with an N-terminal His tag could be crystallized using sodium chloride as a precipitant, the crystals diffracted poorly to only 3.2 A resolution. When the His tag was removed, ZmHP1 crystals were obtained using polyethylene glycol 4000 as a precipitant and the diffraction data were greatly enhanced to 2.4 A resolution. The crystals belonged to the space group P4(1)2(1)2, with one ZmHP1 molecule in the asymmetric unit.
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Affiliation(s)
- Hajime Sugawara
- Laboratory for Communication Mechanisms, RIKEN Plant Science Center, Yokohama 230-0045, Japan.
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Janiak-Spens F, Cook PF, West AH. Kinetic analysis of YPD1-dependent phosphotransfer reactions in the yeast osmoregulatory phosphorelay system. Biochemistry 2005; 44:377-86. [PMID: 15628880 DOI: 10.1021/bi048433s] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In Saccharomyces cerevisiae, the histidine-containing phosphotransfer (HPt) protein YPD1 transfers phosphoryl groups between the three different response regulator domains of SLN1, SSK1, and SKN7 (designated R1, R2, and R3, respectively). Together these proteins form a branched histidine-aspartic acid phosphorelay system through which cells can respond to hyperosmotic and other environmental stresses. The in vivo order of phosphotransfer reactions is believed to proceed from SLN1-R1 to YPD1 and then subsequently to SSK1-R2 or SKN7-R3. The individual phosphoryl transfer reactions between YPD1 and the response regulator domains have been examined kinetically. A maximum forward rate constant of 29 s(-)(1) was determined for the reaction between SLN1-R1 approximately P and YPD1 with a K(d) of 1.4 microM for the SLN1-R1 approximately P.YPD1 complex. In the subsequent reactions, phosphotransfer from YPD1 to SSK1-R2 is very rapid (160 s(-)(1)) and is strongly favored over phosphotransfer to SKN7-R3. Phosphotransfer reactions between YPD1 and SLN1-R1 or SKN7-R3 were reversible. In contrast, no reverse transfer from SSK1-R2 approximately P to YPD1 was observed. These findings are consistent with the notion that SSK1 is constitutively phosphorylated under normal osmotic conditions. In addition, we have examined the roles of several conserved amino acid residues surrounding the phosphorylatable histidine (H64) of YPD1 using phosphoryl transfer reactions involving YPD1 mutants. With respect to phosphoryl transfer from SLN1-R1 approximately P, only one YPD1 mutant (K67A) exhibited an increase in K(d) and thus affects binding of YPD1 to SLN1-R1 approximately P, whereas other mutants (R90A, Q86A, and G68Q) showed a decrease in phosphoryl transfer rate. Only the G68Q-YPD1 mutant was significantly affected in phosphotransfer to SSK1-R2 ( approximately 680-fold decrease in rate in comparison to wild-type). This is the first report of a kinetic analysis of a eukaryotic "two-component" histidine-aspartic acid phosphotransfer system, enabling a comparison of the transfer rates and binding constants to the few bacterial systems that have been studied this way.
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Affiliation(s)
- Fabiola Janiak-Spens
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
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