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Paredes-Martínez F, Eixerés L, Zamora-Caballero S, Casino P. Structural and functional insights underlying recognition of histidine phosphotransfer protein in fungal phosphorelay systems. Commun Biol 2024; 7:814. [PMID: 38965424 PMCID: PMC11224324 DOI: 10.1038/s42003-024-06459-0] [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: 08/17/2023] [Accepted: 06/14/2024] [Indexed: 07/06/2024] Open
Abstract
In human pathogenic fungi, receiver domains from hybrid histidine kinases (hHK) have to recognize one HPt. To understand the recognition mechanism, we have assessed phosphorelay from receiver domains of five hHKs of group III, IV, V, VI, and XI to HPt from Chaetomium thermophilum and obtained the structures of Ct_HPt alone and in complex with the receiver domain of hHK group VI. Our data indicate that receiver domains phosphotransfer to Ct_HPt, show a low affinity for complex formation, and prevent a Leu-Thr switch to stabilize phosphoryl groups, also derived from the structures of the receiver domains of hHK group III and Candida albicans Sln1. Moreover, we have elucidated the envelope structure of C. albicans Ypd1 using small-angle X-ray scattering which reveals an extended flexible conformation of the long loop αD-αE which is not involved in phosphotransfer. Finally, we have analyzed the role of salt bridges in the structure of Ct_HPt alone.
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Affiliation(s)
- Francisco Paredes-Martínez
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Spain
- Instituto Universitario en Biotecnología y Biomedicina (BIOTECMED), Universitat de València, Burjassot, Spain
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (IBV-CSIC), Valencia, Spain
| | - Lluís Eixerés
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Spain
- Instituto Universitario en Biotecnología y Biomedicina (BIOTECMED), Universitat de València, Burjassot, Spain
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (IBV-CSIC), Valencia, Spain
| | - Sara Zamora-Caballero
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (IBV-CSIC), Valencia, Spain
| | - Patricia Casino
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Spain.
- Instituto Universitario en Biotecnología y Biomedicina (BIOTECMED), Universitat de València, Burjassot, Spain.
- CIBER de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain.
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Gentili PL, Stano P. Chemical Neural Networks Inside Synthetic Cells? A Proposal for Their Realization and Modeling. Front Bioeng Biotechnol 2022; 10:927110. [PMID: 35733531 PMCID: PMC9208290 DOI: 10.3389/fbioe.2022.927110] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 05/24/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Pier Luigi Gentili
- Department of Chemistry, Biology and Biotechnology, Università Degli Studi di Perugia, Perugia, Italy
- *Correspondence: Pier Luigi Gentili, ; Pasquale Stano,
| | - Pasquale Stano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
- *Correspondence: Pier Luigi Gentili, ; Pasquale Stano,
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3
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Azorhizobium caulinodans chemotaxis is controlled by an unusual phosphorelay network. J Bacteriol 2021; 204:e0052721. [PMID: 34843377 DOI: 10.1128/jb.00527-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Azorhizobium caulinodans is a nitrogen-fixing bacterium that forms root nodules on its host legume, Sesbania rostrata. This agriculturally significant symbiotic relationship is important in lowland rice cultivation, and allows for nitrogen fixation under flood conditions. Chemotaxis plays an important role in bacterial colonization of the rhizosphere. Plant roots release chemical compounds that are sensed by bacteria, triggering chemotaxis along a concentration gradient toward the roots. This gives motile bacteria a significant competitive advantage during root surface colonization. Although plant-associated bacterial genomes often encode multiple chemotaxis systems, A. caulinodans appears to encode only one. The che cluster on the A. caulinodans genome contains cheA, cheW, cheY2, cheB, and cheR. Two other chemotaxis genes, cheY1 and cheZ, are located independently from the che operon. Both CheY1 and CheY2 are involved in chemotaxis, with CheY1 being the predominant signaling protein. A. caulinodans CheA contains an unusual set of C-terminal domains: a CheW-like/Receiver pair (termed W2-Rec), follows the more common single CheW-like domain. W2-Rec impacts both chemotaxis and CheA function. We found a preference for transfer of phosphoryl groups from CheA to CheY2, rather than to W2-Rec or CheY1, which appears to be involved in flagellar motor binding. Furthermore, we observed increased phosphoryl group stabilities on CheY1 compared to CheY2 or W2-Rec. Finally, CheZ enhanced dephosphorylation of CheY2 substantially more than CheY1, but had no effect on the dephosphorylation rate of W2-Rec. This network of phosphotransfer reactions highlights a previously uncharacterized scheme for regulation of chemotactic responses. IMPORTANCE Chemotaxis allows bacteria to move towards nutrients and away from toxins in their environment. Chemotactic movement provides a competitive advantage over non-specific motion. CheY is an essential mediator of the chemotactic response with phosphorylated and unphosphorylated forms of CheY differentially interacting with the flagellar motor to change swimming behavior. Previously established schemes of CheY dephosphorylation include action of a phosphatase and/or transfer of the phosphoryl group to another receiver domain that acts as a sink. Here, we propose A. caulinodans uses a concerted mechanism in which the Hpt domain of CheA, CheY2, and CheZ function together as a dual sink system to rapidly reset chemotactic signaling. To the best of our knowledge, this mechanism is unlike any that have previously been evaluated. Chemotaxis systems that utilize both receiver and Hpt domains as phosphate sinks likely occur in other bacterial species.
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The many ways that nature has exploited the unusual structural and chemical properties of phosphohistidine for use in proteins. Biochem J 2021; 478:3575-3596. [PMID: 34624072 DOI: 10.1042/bcj20210533] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/15/2021] [Accepted: 09/22/2021] [Indexed: 01/12/2023]
Abstract
Histidine phosphorylation is an important and ubiquitous post-translational modification. Histidine undergoes phosphorylation on either of the nitrogens in its imidazole side chain, giving rise to 1- and 3- phosphohistidine (pHis) isomers, each having a phosphoramidate linkage that is labile at high temperatures and low pH, in contrast with stable phosphomonoester protein modifications. While all organisms routinely use pHis as an enzyme intermediate, prokaryotes, lower eukaryotes and plants also use it for signal transduction. However, research to uncover additional roles for pHis in higher eukaryotes is still at a nascent stage. Since the discovery of pHis in 1962, progress in this field has been relatively slow, in part due to a lack of the tools and techniques necessary to study this labile modification. However, in the past ten years the development of phosphoproteomic techniques to detect phosphohistidine (pHis), and methods to synthesize stable pHis analogues, which enabled the development of anti-phosphohistidine (pHis) antibodies, have accelerated our understanding. Recent studies that employed anti-pHis antibodies and other advanced techniques have contributed to a rapid expansion in our knowledge of histidine phosphorylation. In this review, we examine the varied roles of pHis-containing proteins from a chemical and structural perspective, and present an overview of recent developments in pHis proteomics and antibody development.
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Chen SK, Guan HH, Wu PH, Lin LT, Wu MC, Chang HY, Chen NC, Lin CC, Chuankhayan P, Huang YC, Lin PJ, Chen CJ. Structural insights into the histidine-containing phospho-transfer protein and receiver domain of sensor histidine kinase suggest a complex model in the two-component regulatory system in Pseudomonas aeruginosa. IUCRJ 2020; 7:934-948. [PMID: 32939285 PMCID: PMC7467158 DOI: 10.1107/s2052252520009665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
In Pseudomonas aeruginosa, an important opportunistic pathogen that causes numerous acute and chronic infections, the hybrid two-component system (TCS) regulates the swarming ability and biofilm formation with a multistep phospho-relay, and consists of hybrid-sensor histidine kinase (HK), histidine-containing phospho-transfer protein (Hpt) and response regulator (RR). In this work, two crystal structures of HptB and the receiver domain of HK PA1611 (PA1611REC) of P. aeruginosa have been determined in order to elucidate their interactions for the transfer of the phospho-ryl group. The structure of HptB folds into an elongated four-helix bundle - helices α2, α3, α4 and α5, covered by the short N-terminal helix α1. The imidazole side chain of the conserved active-site histidine residue His57, located near the middle of helix α3, protrudes from the bundle and is exposed to solvent. The structure of PA1611REC possesses a conventional (β/α)5 topology with five-stranded parallel β-sheets folded in the central region, surrounded by five α-helices. The divalent Mg2+ ion is located in the negatively charged active-site cleft and interacts with Asp522, Asp565 and Arg567. The HptB-PA1611REC complex is further modeled to analyze the binding surface and interactions between the two proteins. The model shows a shape complementarity between the convex surface of PA1611REC and the kidney-shaped HptB with fewer residues and a different network involved in interactions compared with other TCS complexes, such as SLN1-R1/YPD1 from Saccharomyces cerevisiae and AHK5RD/AHP1 from Arabidopsis thaliana. These structural results provide a better understanding of the TCS in P. aeruginosa and could potentially lead to the discovery of a new treatment for infection.
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Affiliation(s)
- Shao-Kang Chen
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan City 701, Taiwan
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Hong-Hsiang Guan
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Pei-Hsun Wu
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Li-Ting Lin
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Meng-Chun Wu
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan City 701, Taiwan
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Hwan-You Chang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Nai-Chi Chen
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chien-Chih Lin
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Phimonphan Chuankhayan
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yen-Chieh Huang
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Pei-Ju Lin
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chun-Jung Chen
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan City 701, Taiwan
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan
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Trajtenberg F, Buschiazzo A. Protein Dynamics in Phosphoryl-Transfer Signaling Mediated by Two-Component Systems. Methods Mol Biol 2020; 2077:1-18. [PMID: 31707648 DOI: 10.1007/978-1-4939-9884-5_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The ability to perceive the environment, an essential attribute in living organisms, is linked to the evolution of signaling proteins that recognize specific signals and execute predetermined responses. Such proteins constitute concerted systems that can be as simple as a unique protein, able to recognize a ligand and exert a phenotypic change, or extremely complex pathways engaging dozens of different proteins which act in coordination with feedback loops and signal modulation. To understand how cells sense their surroundings and mount specific adaptive responses, we need to decipher the molecular workings of signal recognition, internalization, transfer, and conversion into chemical changes inside the cell. Protein allostery and dynamics play a central role. Here, we review recent progress on the study of two-component systems, important signaling machineries of prokaryotes and lower eukaryotes. Such systems implicate a sensory histidine kinase and a separate response regulator protein. Both components exploit protein flexibility to effect specific conformational rearrangements, modulating protein-protein interactions, and ultimately transmitting information accurately. Recent work has revealed how histidine kinases switch between discrete functional states according to the presence or absence of the signal, shifting key amino acid positions that define their catalytic activity. In concert with the cognate response regulator's allosteric changes, the phosphoryl-transfer flow during the signaling process is exquisitely fine-tuned for proper specificity, efficiency and directionality.
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Affiliation(s)
- Felipe Trajtenberg
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Alejandro Buschiazzo
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay.
- Département de Microbiologie, Institut Pasteur, Paris, France.
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Buschiazzo A, Trajtenberg F. Two-Component Sensing and Regulation: How Do Histidine Kinases Talk with Response Regulators at the Molecular Level? Annu Rev Microbiol 2019; 73:507-528. [PMID: 31226026 DOI: 10.1146/annurev-micro-091018-054627] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Perceiving environmental and internal information and reacting in adaptive ways are essential attributes of living organisms. Two-component systems are relevant protein machineries from prokaryotes and lower eukaryotes that enable cells to sense and process signals. Implicating sensory histidine kinases and response regulator proteins, both components take advantage of protein phosphorylation and flexibility to switch conformations in a signal-dependent way. Dozens of two-component systems act simultaneously in any given cell, challenging our understanding about the means that ensure proper connectivity. This review dives into the molecular level, attempting to summarize an emerging picture of how histidine kinases and cognate response regulators achieve required efficiency, specificity, and directionality of signaling pathways, properties that rely on protein:protein interactions. α helices that carry information through long distances, the fine combination of loose and specific kinase/regulator interactions, and malleable reaction centers built when the two components meet emerge as relevant universal principles.
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Affiliation(s)
- Alejandro Buschiazzo
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; , .,Integrative Microbiology of Zoonotic Agents, Department of Microbiology, Institut Pasteur, Paris 75015, France
| | - Felipe Trajtenberg
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; ,
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Lowry RC, Milner DS, Al-Bayati AMS, Lambert C, Francis VI, Porter SL, Sockett RE. Evolutionary diversification of the RomR protein of the invasive deltaproteobacterium, Bdellovibrio bacteriovorus. Sci Rep 2019; 9:5007. [PMID: 30899045 PMCID: PMC6428892 DOI: 10.1038/s41598-019-41263-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/27/2019] [Indexed: 01/19/2023] Open
Abstract
Bdellovibrio bacteriovorus is a predatory deltaproteobacterium that encounters individual Gram-negative prey bacteria with gliding or swimming motility, and then is able to invade such prey cells via type IVa pilus-dependent mechanisms. Movement control (pili or gliding) in other deltaproteobacteria, such as the pack hunting Myxococcus xanthus, uses a response regulator protein, RomRMx (which dynamically relocalises between the cell poles) and a GTPase, MglAMx, previously postulated as an interface between the FrzMx chemosensory system and gliding or pilus-motility apparatus, to produce regulated bidirectional motility. In contrast, B. bacteriovorus predation is a more singular encounter between a lone predator and prey; contact is always via the piliated, non-flagellar pole of the predator, involving MglABd, but no Frz system. In this new study, tracking fluorescent RomRBd microscopically during predatory growth shows that it does not dynamically relocalise, in contrast to the M. xanthus protein; instead having possible roles in growth events. Furthermore, transcriptional start analysis, site-directed mutagenesis and bacterial two-hybrid interaction studies, indicate an evolutionary loss of RomRBd activation (via receiver domain phosphorylation) in this lone hunting bacterium, demonstrating divergence from its bipolar role in motility in pack-hunting M. xanthus and further evolution that may differentiate lone from pack predators.
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Affiliation(s)
- Rebecca C Lowry
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - David S Milner
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.,Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Asmaa M S Al-Bayati
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.,Northern Technical University, Mosul, Iraq
| | - Carey Lambert
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - Vanessa I Francis
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Steven L Porter
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.
| | - R E Sockett
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
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Dynamic domain arrangement of CheA-CheY complex regulates bacterial thermotaxis, as revealed by NMR. Sci Rep 2017; 7:16462. [PMID: 29184123 PMCID: PMC5705603 DOI: 10.1038/s41598-017-16755-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/16/2017] [Indexed: 01/19/2023] Open
Abstract
Bacteria utilize thermotaxis signal transduction proteins, including CheA, and CheY, to switch the direction of the cell movement. However, the thermally responsive machinery enabling warm-seeking behavior has not been identified. Here we examined the effects of temperature on the structure and dynamics of the full-length CheA and CheY complex, by NMR. Our studies revealed that the CheA-CheY complex exists in equilibrium between multiple states, including one state that is preferable for the autophosphorylation of CheA, and another state that is preferable for the phosphotransfer from CheA to CheY. With increasing temperature, the equilibrium shifts toward the latter state. The temperature-dependent population shift of the dynamic domain arrangement of the CheA-CheY complex induced changes in the concentrations of phosphorylated CheY that are comparable to those induced by chemical attractants or repellents. Therefore, the dynamic domain arrangement of the CheA-CheY complex functions as the primary thermally responsive machinery in warm-seeking behavior.
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Gupta V, Chaudhary N, Aggarwal S, Adlakha N, Gulati P, Bhatnagar R. Functional analysis of BAS2108-2109 two component system: Evidence for protease regulation in Bacillus anthracis. Int J Biochem Cell Biol 2017; 89:71-84. [PMID: 28602714 DOI: 10.1016/j.biocel.2017.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/01/2017] [Accepted: 06/03/2017] [Indexed: 01/18/2023]
Abstract
BACKGROUND Bacillus anthracis (BA) is a major bioterrorism concern which has evolved complex regulatory mechanisms for its virulence factors. Secreted proteases play an imperative role in the pathogenesis of BA, however their regulation remains elusive. Two component systems (TCS) are often employed by bacteria to sense and adapt to the environmental perturbations. In several pathogens, TCS are commonly associated with the regulation of virulence factors including proteases. The genome of BA encodes 41 TCS pairs, however, the role of any TCS in regulation of its proteases is not known. PRINCIPAL FINDINGS The study established BAS2108-2109 as a prototypical TCS where BAS2108 functions as a histidine kinase and BAS2109 as the response regulator. The expression of BAS2109 was found to be elevated under host simulated conditions and in pellicle forming cells. Electrophoretic mobility shift assay (EMSA) and lacZ reporter assay revealed positive autoregulation of the BAS2108-2109 operon by BAS2109. Collective analysis of ANS assay and EMSA demonstrated Lys167, Thr179 and Thr182 residues are crucial for the DNA binding activity of BAS2109. EMSA analysis further highlighted BAS2109 as the transcriptional regulator for different genes of BA, particularly proteases. Upregulation of proteases in BA overexpressing BAS2109 further strengthen its role in protease regulation. SIGNIFICANCE This is the first report to identify a TCS pair for its role in the regulation of proteases of BA. Importance of proteases in the pathogenesis of BA is well documented, therefore, studying the regulatory networks governing their expression will help in identification of new drug targets.
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Affiliation(s)
- Vatika Gupta
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India; Medical Microbiology and Bioprocess Technology Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Neha Chaudhary
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Somya Aggarwal
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Nidhi Adlakha
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Pooja Gulati
- Medical Microbiology and Bioprocess Technology Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India.
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Aggarwal S, Somani VK, Gupta V, Kaur J, Singh D, Grover A, Bhatnagar R. Functional characterization of PhoPR two component system and its implication in regulating phosphate homeostasis in Bacillus anthracis. Biochim Biophys Acta Gen Subj 2017; 1861:2956-2970. [DOI: 10.1016/j.bbagen.2016.09.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 09/14/2016] [Accepted: 09/21/2016] [Indexed: 12/24/2022]
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12
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Trajtenberg F, Imelio JA, Machado MR, Larrieux N, Marti MA, Obal G, Mechaly AE, Buschiazzo A. Regulation of signaling directionality revealed by 3D snapshots of a kinase:regulator complex in action. eLife 2016; 5:e21422. [PMID: 27938660 PMCID: PMC5231405 DOI: 10.7554/elife.21422] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 12/09/2016] [Indexed: 01/19/2023] Open
Abstract
Two-component systems (TCS) are protein machineries that enable cells to respond to input signals. Histidine kinases (HK) are the sensory component, transferring information toward downstream response regulators (RR). HKs transfer phosphoryl groups to their specific RRs, but also dephosphorylate them, overall ensuring proper signaling. The mechanisms by which HKs discriminate between such disparate directions, are yet unknown. We now disclose crystal structures of the HK:RR complex DesK:DesR from Bacillus subtilis, comprising snapshots of the phosphotransfer and the dephosphorylation reactions. The HK dictates the reactional outcome through conformational rearrangements that include the reactive histidine. The phosphotransfer center is asymmetric, poised for dissociative nucleophilic substitution. The structural bases of HK phosphatase/phosphotransferase control are uncovered, and the unexpected discovery of a dissociative reactional center, sheds light on the evolution of TCS phosphotransfer reversibility. Our findings should be applicable to a broad range of signaling systems and instrumental in synthetic TCS rewiring.
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Affiliation(s)
- Felipe Trajtenberg
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Juan A Imelio
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Matías R Machado
- Biomolecular Simulations, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Nicole Larrieux
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Marcelo A Marti
- Departamento de Química Biológica e IQUIBICEN-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gonzalo Obal
- Protein Biophysics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Ariel E Mechaly
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Alejandro Buschiazzo
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Département de Microbiologie, Institut Pasteur, Paris, France
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Immormino RM, Silversmith RE, Bourret RB. A Variable Active Site Residue Influences the Kinetics of Response Regulator Phosphorylation and Dephosphorylation. Biochemistry 2016; 55:5595-5609. [PMID: 27589219 PMCID: PMC5050157 DOI: 10.1021/acs.biochem.6b00645] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Two-component regulatory systems, minimally composed of a sensor kinase and a response regulator protein, are common mediators of signal transduction in microorganisms. All response regulators contain a receiver domain with conserved active site residues that catalyze the signal activating and deactivating phosphorylation and dephosphorylation reactions. We explored the impact of variable active site position T+1 (one residue C-terminal to the conserved Thr/Ser) on reaction kinetics and signaling fidelity, using wild type and mutant Escherichia coli CheY, CheB, and NarL to represent the three major sequence classes observed across response regulators: Ala/Gly, Ser/Thr, and Val/Ile/Met, respectively, at T+1. Biochemical and structural data together suggested that different amino acids at T+1 impacted reaction kinetics by altering access to the active site while not perturbing overall protein structure. A given amino acid at position T+1 had similar effects on autodephosphorylation in each protein background tested, likely by modulating access of the attacking water molecule to the active site. Similarly, rate constants for CheY autophosphorylation with three different small molecule phosphodonors were consistent with the steric constraints on access to the phosphorylation site arising from combination of specific phosphodonors with particular amino acids at T+1. Because other variable active site residues also influence response regulator phosphorylation biochemistry, we began to explore how context (here, the amino acid at T+2) affected the influence of position T+1 on CheY autocatalytic reactions. Finally, position T+1 affected the fidelity and kinetics of phosphotransfer between sensor kinases and response regulators but was not a primary determinant of their interaction.
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Affiliation(s)
| | - Ruth E. Silversmith
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7290, United States
| | - Robert B. Bourret
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7290, United States
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14
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Silversmith RE, Wang B, Fulcher NB, Wolfgang MC, Bourret RB. Phosphoryl Group Flow within the Pseudomonas aeruginosa Pil-Chp Chemosensory System: DIFFERENTIAL FUNCTION OF THE EIGHT PHOSPHOTRANSFERASE AND THREE RECEIVER DOMAINS. J Biol Chem 2016; 291:17677-91. [PMID: 27354279 DOI: 10.1074/jbc.m116.737528] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 11/06/2022] Open
Abstract
Bacterial chemosensory signal transduction systems that regulate motility by type IV pili (T4P) can be markedly more complex than related flagellum-based chemotaxis systems. In T4P-based systems, the CheA kinase often contains numerous potential sites of phosphorylation, but the signaling mechanisms of these systems are unknown. In Pseudomonas aeruginosa, the Pil-Chp system regulates T4P-mediated twitching motility and cAMP levels, both of which play roles in pathogenesis. The Pil-Chp histidine kinase (ChpA) has eight "Xpt" domains; six are canonical histidine-containing phosphotransfer (Hpt) domains and two have a threonine (Tpt) or serine (Spt) in place of the histidine. Additionally, there are two stand-alone receiver domains (PilG and PilH) and a ChpA C-terminal receiver domain (ChpArec). Here, we demonstrate that the ChpA Xpts are functionally divided into three categories as follows: (i) those phosphorylated with ATP (Hpt4-6); (ii) those reversibly phosphorylated by ChpArec (Hpt2-6), and (iii) those with no detectable phosphorylation (Hpt1, Spt, and Tpt). There was rapid phosphotransfer from Hpt2-6 to ChpArec and from Hpt3 to PilH, whereas transfer to PilG was slower. ChpArec also had a rapid rate of autodephosphorylation. The biochemical results together with in vivo cAMP and twitching phenotypes of key ChpA phosphorylation site point mutants supported a scheme whereby ChpArec functions both as a phosphate sink and a phosphotransfer element linking Hpt4-6 to Hpt2-3. Hpt2 and Hpt3 are likely the dominant sources of phosphoryl groups for PilG and PilH, respectively. The data are synthesized in a signaling circuit that contains fundamental features of two-component phosphorelays.
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Affiliation(s)
| | - Boya Wang
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Nanette B Fulcher
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Matthew C Wolfgang
- From the Department of Microbiology and Immunology and Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599
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15
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Agrawal R, Sahoo BK, Saini DK. Cross-talk and specificity in two-component signal transduction pathways. Future Microbiol 2016; 11:685-97. [PMID: 27159035 DOI: 10.2217/fmb-2016-0001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two-component signaling systems (TCSs) are composed of two proteins, sensor kinases and response regulators, which can cross-talk and integrate information between them by virtue of high-sequence conservation and modular nature, to generate concerted and diversified responses. However, TCSs have been shown to be insulated, to facilitate linear signal transmission and response generation. Here, we discuss various mechanisms that confer specificity or cross-talk among TCSs. The presented models are supported with evidence that indicate the physiological significance of the observed TCS signaling architecture. Overall, we propose that the signaling topology of any TCSs cannot be predicted using obvious sequence or structural rules, as TCS signaling is regulated by multiple factors, including spatial and temporal distribution of the participating proteins.
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Affiliation(s)
- Ruchi Agrawal
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, India
| | - Bikash Kumar Sahoo
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, India
| | - Deepak Kumar Saini
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, India.,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
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16
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Pekárová B, Szmitkowska A, Dopitová R, Degtjarik O, Žídek L, Hejátko J. Structural Aspects of Multistep Phosphorelay-Mediated Signaling in Plants. MOLECULAR PLANT 2016; 9:71-85. [PMID: 26633861 DOI: 10.1016/j.molp.2015.11.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 11/17/2015] [Accepted: 11/18/2015] [Indexed: 05/16/2023]
Abstract
The multistep phosphorelay (MSP) is a central signaling pathway in plants integrating a wide spectrum of hormonal and environmental inputs and controlling numerous developmental adaptations. For the thorough comprehension of the molecular mechanisms underlying the MSP-mediated signal recognition and transduction, the detailed structural characterization of individual members of the pathway is critical. In this review we describe and discuss the recently known crystal and nuclear magnetic resonance structures of proteins acting in MSP signaling in higher plants, focusing particularly on cytokinin and ethylene signaling in Arabidopsis thaliana. We discuss the range of functional aspects of available structural information including determination of ligand specificity, activation of the receptor via its autophosphorylation, and downstream signal transduction through the phosphorelay. We compare the plant structures with their bacterial counterparts and show that although the overall similarity is high, the differences in structural details are frequent and functionally important. Finally, we discuss emerging knowledge on molecular recognition mechanisms in the MSP, and mention the latest findings regarding structural determinants of signaling specificity in the Arabidopsis MSP that could serve as a general model of this pathway in all higher plants.
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Affiliation(s)
- Blanka Pekárová
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Agnieszka Szmitkowska
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Radka Dopitová
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Oksana Degtjarik
- Faculty of Science, Institute of Chemistry and Biochemistry, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Lukáš Žídek
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Jan Hejátko
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
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17
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Nguyen MP, Yoon JM, Cho MH, Lee SW. Prokaryotic 2-component systems and the OmpR/PhoB superfamily. Can J Microbiol 2015; 61:799-810. [DOI: 10.1139/cjm-2015-0345] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In bacteria, 2-component regulatory systems (TCSs) are the critical information-processing pathways that link stimuli to specific adaptive responses. Signals perceived by membrane sensors, which are generally histidine kinases, are transmitted by response regulators (RRs) to allow cells to cope rapidly and effectively with environmental challenges. Over the past few decades, genes encoding components of TCSs and their responsive proteins have been identified, crystal structures have been described, and signaling mechanisms have been elucidated. Here, we review recent findings and interesting breakthroughs in bacterial TCS research. Furthermore, we discuss structural features, mechanisms of activation and regulation, and cross-regulation of RRs, with a focus on the largest RR family, OmpR/PhoB, to provide a comprehensive overview of these critically important signaling molecules.
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Affiliation(s)
| | - Joo-Mi Yoon
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
| | - Man-Ho Cho
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
| | - Sang-Won Lee
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
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18
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Two Proteins Form a Heteromeric Bacterial Self-Recognition Complex in Which Variable Subdomains Determine Allele-Restricted Binding. mBio 2015; 6:e00251. [PMID: 26060269 PMCID: PMC4471559 DOI: 10.1128/mbio.00251-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
UNLABELLED Self- versus nonself-recognition in bacteria has been described recently through genetic analyses in multiple systems; however, understanding of the biochemical properties and mechanisms of recognition-determinant proteins remains limited. Here we extend the molecular and biochemical understanding of two recognition-determinant proteins in bacteria. We have found that a heterotypic complex is formed between two bacterial self-recognition proteins, IdsD and IdsE, the genes of which have been shown to genetically encode the determinants for strain-specific identity in the opportunistic bacterial pathogen Proteus mirabilis. This IdsD-IdsE complex forms independently of other P. mirabilis-encoded self-recognition proteins. We have also shown that the binding between IdsD and IdsE is strain- and allele-specific. The specificity for interactions is encoded within a predicted membrane-spanning subdomain within each protein that contains stretches of unique amino acids in each P. mirabilis variant. Finally, we have demonstrated that this in vitro IdsD-IdsE binding interaction correlates to in vivo population identity, suggesting that the binding interactions between IdsD and IdsE are part of a cellular pathway that underpins self-recognition behavior in P. mirabilis and drives bacterial population sociality. IMPORTANCE Here we demonstrate that two proteins, the genes of which were genetically shown to encode determinants of self-identity in bacteria, bind in vitro in an allele-restricted interaction, suggesting that molecular recognition between these two proteins is a mechanism underpinning self-recognition behaviors in P. mirabilis. Binding specificity in each protein is encapsulated in a variable region subdomain that is predicted to span the membrane, suggesting that the interaction occurs in the cell envelope. Furthermore, conversion of binding affinities in vitro correlates with conversion of self-identity in vivo, suggesting that this molecular recognition might help to drive population behaviors.
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19
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A Social Medium: ASM's 5th Cell-Cell Communication in Bacteria Meeting in Review. J Bacteriol 2015; 197:2084-2093. [PMID: 25917904 DOI: 10.1128/jb.00161-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The 5th American Society for Microbiology Conference on Cell-Cell Communication in Bacteria (CCCB-5), which convened from October 18 - 21, 2014 in San Antonio, Texas, highlighted recent advances in our understanding of microbial intercellular signaling. While the CCCB meetings arose from interests in pheromone signaling and quorum sensing, it was evident at CCCB-5 that the cell-cell communication field is continuing to mature, expanding into new areas and integrating cutting-edge technologies. In this review, we recap some of the research discussed at CCCB-5 as well as the questions that have arisen from it.
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20
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Verma V, Sivaraman J, Srivastava AK, Sadanandom A, Kumar PP. Destabilization of interaction between cytokinin signaling intermediates AHP1 and ARR4 modulates Arabidopsis development. THE NEW PHYTOLOGIST 2015; 206:726-737. [PMID: 25643735 DOI: 10.1111/nph.13297] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 11/26/2014] [Indexed: 06/04/2023]
Abstract
Eukaryotic two-component signaling involves the His-Asp-His-Asp multistep phosphorelay (MSP). In Arabidopsis thaliana, cytokinin-mediated MSP signaling intermediates include histidine kinases (HKs), histidine phosphotransfer proteins (Hpts) and response regulators (RRs). The structure-function relationship of interaction between Hpt (e.g. AHP1) and RR (e.g. ARR4) is poorly understood. Using a homology model and yeast two-hybrid analysis, we identified key amino acids of ARR4 at the AHP1-ΔARR4((16-175)) interaction interface. Mutating them in Arabidopsis (arr3,4,5,6,8,9 hextuple mutant background) and performing root length assays provided functional relevance, and coimmunoprecipitation (coIP) assay provided biochemical evidence for the interaction. The homology model mimics crystal structures of Hpt-RR complexes. Mutating selected interface residues of ARR4 either abolished or destabilized the interaction. D45A and Y96A mutations weakened interaction with AHP1, and exhibited weaker rescue of root elongation in the hextuple mutants. CoIP analysis using cytokinin-treated transgenic Arabidopsis seedlings provided biochemical evidence for weakened AHP1-ARR4 interaction. The relevance of the selected residues for the interaction was further validated in two independent pairs of Hpt-RR proteins from Arabidopsis and rice (Oryza sativa). Our data provide evidence of a link between Hpt-RR interaction affinity and regulation of downstream functions of RRs. This establishes a structure-function relationship for the final step of a eukaryotic MSP signal cascade.
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Affiliation(s)
- Vivek Verma
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 117543, Singapore, Singapore
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21
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Comparative analysis of wolbachia genomes reveals streamlining and divergence of minimalist two-component systems. G3-GENES GENOMES GENETICS 2015; 5:983-96. [PMID: 25809075 PMCID: PMC4426382 DOI: 10.1534/g3.115.017137] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Two-component regulatory systems are commonly used by bacteria to coordinate intracellular responses with environmental cues. These systems are composed of functional protein pairs consisting of a sensor histidine kinase and cognate response regulator. In contrast to the well-studied Caulobacter crescentus system, which carries dozens of these pairs, the streamlined bacterial endosymbiont Wolbachia pipientis encodes only two pairs: CckA/CtrA and PleC/PleD. Here, we used bioinformatic tools to compare characterized two-component system relays from C. crescentus, the related Anaplasmataceae species Anaplasma phagocytophilum and Ehrlichia chaffeensis, and 12 sequenced Wolbachia strains. We found the core protein pairs and a subset of interacting partners to be highly conserved within Wolbachia and these other Anaplasmataceae. Genes involved in two-component signaling were positioned differently within the various Wolbachia genomes, whereas the local context of each gene was conserved. Unlike Anaplasma and Ehrlichia, Wolbachia two-component genes were more consistently found clustered with metabolic genes. The domain architecture and key functional residues standard for two-component system proteins were well-conserved in Wolbachia, although residues that specify cognate pairing diverged substantially from other Anaplasmataceae. These findings indicate that Wolbachia two-component signaling pairs share considerable functional overlap with other α-proteobacterial systems, whereas their divergence suggests the potential for regulatory differences and cross-talk.
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22
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Allosteric activation of bacterial response regulators: the role of the cognate histidine kinase beyond phosphorylation. mBio 2014; 5:e02105. [PMID: 25406381 PMCID: PMC4251995 DOI: 10.1128/mbio.02105-14] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Response regulators are proteins that undergo transient phosphorylation, connecting specific signals to adaptive responses. Remarkably, the molecular mechanism of response regulator activation remains elusive, largely because of the scarcity of structural data on multidomain response regulators and histidine kinase/response regulator complexes. We now address this question by using a combination of crystallographic data and functional analyses in vitro and in vivo, studying DesR and its cognate sensor kinase DesK, a two-component system that controls membrane fluidity in Bacillus subtilis. We establish that phosphorylation of the receiver domain of DesR is allosterically coupled to two distinct exposed surfaces of the protein, controlling noncanonical dimerization/tetramerization, cooperative activation, and DesK binding. One of these surfaces is critical for both homodimerization- and kinase-triggered allosteric activations. Moreover, DesK induces a phosphorylation-independent activation of DesR in vivo, uncovering a novel and stringent level of specificity among kinases and regulators. Our results support a model that helps to explain how response regulators restrict phosphorylation by small-molecule phosphoryl donors, as well as cross talk with noncognate sensors. The ability to sense and respond to environmental variations is an essential property for cell survival. Two-component systems mediate key signaling pathways that allow bacteria to integrate extra- or intracellular signals. Here we focus on the DesK/DesR system, which acts as a molecular thermometer in B. subtilis, regulating the cell membrane’s fluidity. Using a combination of complementary approaches, including determination of the crystal structures of active and inactive forms of the response regulator DesR, we unveil novel molecular mechanisms of DesR’s activation switch. In particular, we show that the association of the cognate histidine kinase DesK triggers DesR activation beyond the transfer of the phosphoryl group. On the basis of sequence and structural analyses of other two-component systems, this activation mechanism appears to be used in a wide range of sensory systems, contributing a further level of specificity control among different signaling pathways.
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23
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Influence of the AgrC-AgrA complex on the response time of Staphylococcus aureus quorum sensing. J Bacteriol 2014; 196:2876-88. [PMID: 24858185 DOI: 10.1128/jb.01530-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The Staphylococcus aureus agr quorum-sensing system plays a major role in the transition from the persistent to the virulent phenotype. S. aureus agr type I to IV strains are characterized by mutations in the sensor domain of the histidine kinase AgrC and differences in the sequences of the secreted autoinducing peptides (AIP). Here we demonstrate that interactions between the cytosolic domain of AgrC (AgrCCyto) and the response regulator domain of AgrA (AgrARR) dictate the spontaneity of the cellular response to AIP stimuli. The crystal structure of AgrCCyto provided a basis for a mechanistic model of AgrC-AgrA interactions. This model enabled an analysis of the biochemical and biophysical parameters of AgrC-AgrA interactions in the context of the conformational features of the AgrC-AgrA complex. This analysis revealed distinct sequence and conformational features that determine the affinity, specificity, and kinetics of the phosphotransfer reaction. This step, which governs the response time for transcriptional reengineering triggered by an AIP stimulus, is independent of the agr type and similar for agonist and antagonist stimuli. These experimental data could serve as a basis on which to validate simulations of the quorum-sensing response and for strategies that employ the agr quorum-sensing system to combat biofilm formation in S. aureus infections.
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24
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Sandler I, Zigdon N, Levy E, Aharoni A. The functional importance of co-evolving residues in proteins. Cell Mol Life Sci 2014; 71:673-82. [PMID: 23995987 PMCID: PMC11113390 DOI: 10.1007/s00018-013-1458-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 07/26/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
Abstract
Computational approaches for detecting co-evolution in proteins allow for the identification of protein-protein interaction networks in different organisms and the assignment of function to under-explored proteins. The detection of co-variation of amino acids within or between proteins, moreover, allows for the discovery of residue-residue contacts and highlights functional residues that can affect the binding affinity, catalytic activity, or substrate specificity of a protein. To explore the functional impact of co-evolutionary changes in proteins, a combined experimental and computational approach must be recruited. Here, we review recent studies that apply computational and experimental tools to obtain novel insight into the structure, function, and evolution of proteins. Specifically, we describe the application of co-evolutionary analysis for predicting high-resolution three-dimensional structures of proteins. In addition, we describe computational approaches followed by experimental analysis for identifying specificity-determining residues in proteins. Finally, we discuss studies addressing the importance of such residues in terms of the functional divergence of proteins, allowing proteins to evolve new functions while avoiding crosstalk with existing cellular pathways or forming reproductive barriers and hence promoting speciation.
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Affiliation(s)
- Inga Sandler
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
| | - Nitzan Zigdon
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
| | - Efrat Levy
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
| | - Amir Aharoni
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
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25
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Mutational analysis of the P1 phosphorylation domain in Escherichia coli CheA, the signaling kinase for chemotaxis. J Bacteriol 2013; 196:257-64. [PMID: 24163342 DOI: 10.1128/jb.01167-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The histidine autokinase CheA functions as the central processing unit in the Escherichia coli chemotaxis signaling machinery. CheA receives autophosphorylation control inputs from chemoreceptors and in turn regulates the flux of signaling phosphates to the CheY and CheB response regulator proteins. Phospho-CheY changes the direction of flagellar rotation; phospho-CheB covalently modifies receptor molecules during sensory adaptation. The CheA phosphorylation site, His-48, lies in the N-terminal P1 domain, which must engage the CheA ATP-binding domain, P4, to initiate an autophosphorylation reaction cycle. The docking determinants for the P1-P4 interaction have not been experimentally identified. We devised mutant screens to isolate P1 domains with impaired autophosphorylation or phosphotransfer activities. One set of P1 mutants identified amino acid replacements at surface-exposed residues distal to His-48. These lesions reduced the rate of P1 transphosphorylation by P4. However, once phosphorylated, the mutant P1 domains transferred phosphate to CheY at the wild-type rate. Thus, these P1 mutants appear to define interaction determinants for P1-P4 docking during the CheA autophosphorylation reaction.
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26
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Biswas M, Dey S, Khamrui S, Sen U, Dasgupta J. Conformational barrier of CheY3 and inability of CheY4 to bind FliM control the flagellar motor action in Vibrio cholerae. PLoS One 2013; 8:e73923. [PMID: 24066084 PMCID: PMC3774744 DOI: 10.1371/journal.pone.0073923] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 07/26/2013] [Indexed: 12/22/2022] Open
Abstract
Vibrio cholerae contains multiple copies of chemotaxis response regulator (VcCheY1-VcCheY4) whose functions are elusive yet. Although previous studies suggested that only VcCheY3 directly switches the flagellar rotation, the involvement of VcCheY4 in chemotaxis could not be ruled out. None of these studies, however, focused on the structure, mechanism of activation or molecular basis of FliM binding of the VcCheYs. From the crystal structures of Ca(2+) and Mg(2+) bound VcCheY3 we proposed the presence of a conformational barrier composed of the hydrophobic packing of W61, M88 and V106 and a unique hydrogen bond between T90 and Q97 in VcCheY3. Lesser fluorescence quenching and higher Km value of VcCheY3, compared to its mutants VcCheY3-Q97A and VcCheY3-Q97A/E100A supported our proposition. Furthermore, aforesaid biochemical data, in conjunction with the structure of VcCheY3-Q97A, indicated that the coupling of T90 and Q97 restricts the movement of T90 toward the active site reducing the stabilization of the bound phosphate and effectively promoting autodephosphorylation of VcCheY3. The structure of BeF3(-) activated VcCheY3 insisted us to argue that elevated temperature and/or adequacy of phosphate pool might break the barrier of the free-state VcCheY3 and the conformational changes, required for FliM binding, occur upon phosphorylation. Structure of VcCheY4 has been solved in the free and sulfated states. VcCheY4(sulf), containing a bound sulfate at the active site, appears to be more compact and stable with a longer α4 helix, shorter β4α4 loop and hydrogen bond between T82 and the sulfate compared to VcCheY4(free). While pull down assay of VcCheYs with VcFliMNM showed that only activated VcCheY3 can interact with VcFliMNM and VcCheY4 cannot, a knowledge based docking explained the molecular mechanism of the interactions between VcCheY3 and VcFliM and identified the limitations of VcCheY4 to interact with VcFliM even in its phosphorylated state.
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Affiliation(s)
- Maitree Biswas
- Department of Biotechnology, St. Xavier’s College, Kolkata, India
| | - Sanjay Dey
- Department of Biotechnology, St. Xavier’s College, Kolkata, India
| | - Susmita Khamrui
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Udayaditya Sen
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Jhimli Dasgupta
- Department of Biotechnology, St. Xavier’s College, Kolkata, India
- * E-mail:
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27
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Podgornaia AI, Casino P, Marina A, Laub MT. Structural basis of a rationally rewired protein-protein interface critical to bacterial signaling. Structure 2013; 21:1636-47. [PMID: 23954504 DOI: 10.1016/j.str.2013.07.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 06/25/2013] [Accepted: 07/03/2013] [Indexed: 02/01/2023]
Abstract
Two-component signal transduction systems typically involve a sensor histidine kinase that specifically phosphorylates a single, cognate response regulator. This protein-protein interaction relies on molecular recognition via a small set of residues in each protein. To better understand how these residues determine the specificity of kinase-substrate interactions, we rationally rewired the interaction interface of a Thermotoga maritima two-component system, HK853-RR468, to match that found in a different two-component system, Escherichia coli PhoR-PhoB. The rewired proteins interacted robustly with each other, but no longer interacted with the parent proteins. Analysis of the crystal structures of the wild-type and mutant protein complexes and a systematic mutagenesis study reveal how individual mutations contribute to the rewiring of interaction specificity. Our approach and conclusions have implications for studies of other protein-protein interactions and protein evolution and for the design of novel protein interfaces.
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Affiliation(s)
- Anna I Podgornaia
- Computational and Systems Biology Initiative, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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28
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Blair JA, Xu Q, Childers WS, Mathews II, Kern JW, Eckart M, Deacon AM, Shapiro L. Branched signal wiring of an essential bacterial cell-cycle phosphotransfer protein. Structure 2013; 21:1590-601. [PMID: 23932593 DOI: 10.1016/j.str.2013.06.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 06/04/2013] [Accepted: 06/21/2013] [Indexed: 11/24/2022]
Abstract
Vital to bacterial survival is the faithful propagation of cellular signals, and in Caulobacter crescentus, ChpT is an essential mediator within the cell-cycle circuit. ChpT functions as a histidine-containing phosphotransfer protein (HPt) that shuttles a phosphoryl group from the receiver domain of CckA, the upstream hybrid histidine kinase (HK), to one of two downstream response regulators (CtrA or CpdR) that controls cell-cycle progression. To understand how ChpT interacts with multiple signaling partners, we solved the crystal structure of ChpT at 2.3 Å resolution. ChpT adopts a pseudo-HK architecture but does not bind ATP. We identified two point mutation classes affecting phosphotransfer and cell morphology: one that globally impairs ChpT phosphotransfer, and a second that mediates partner selection. Importantly, a small set of conserved ChpT residues promotes signaling crosstalk and contributes to the branched signaling that activates the master regulator CtrA while inactivating the CtrA degradation signal, CpdR.
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Affiliation(s)
- Jimmy A Blair
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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29
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Hill K, Mathews DE, Kim HJ, Street IH, Wildes SL, Chiang YH, Mason MG, Alonso JM, Ecker JR, Kieber JJ, Schaller GE. Functional characterization of type-B response regulators in the Arabidopsis cytokinin response. PLANT PHYSIOLOGY 2013; 162:212-24. [PMID: 23482873 PMCID: PMC3641203 DOI: 10.1104/pp.112.208736] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 03/10/2013] [Indexed: 05/20/2023]
Abstract
Cytokinins play critical roles in plant growth and development, with the transcriptional response to cytokinin being mediated by the type-B response regulators. In Arabidopsis (Arabidopsis thaliana), type-B response regulators (ARABIDOPSIS RESPONSE REGULATORS [ARRs]) form three subfamilies based on phylogenic analysis, with subfamily 1 having seven members and subfamilies 2 and 3 each having two members. Cytokinin responses are predominantly mediated by subfamily 1 members, with cytokinin-mediated effects on root growth and root meristem size correlating with type-B ARR expression levels. To determine which type-B ARRs can functionally substitute for the subfamily 1 members ARR1 or ARR12, we expressed different type-B ARRs from the ARR1 promoter and assayed their ability to rescue arr1 arr12 double mutant phenotypes. ARR1, as well as a subset of other subfamily 1 type-B ARRs, restore the cytokinin sensitivity to arr1 arr12. Expression of ARR10 from the ARR1 promoter results in cytokinin hypersensitivity and enhances shoot regeneration from callus tissue, correlating with enhanced stability of the ARR10 protein compared with the ARR1 protein. Examination of transfer DNA insertion mutants in subfamilies 2 and 3 revealed little effect on several well-characterized cytokinin responses. However, a member of subfamily 2, ARR21, restores cytokinin sensitivity to arr1 arr12 roots when expressed from the ARR1 promoter, indicating functional conservation of this divergent family member. Our results indicate that the type-B ARRs have diverged in function, such that some, but not all, can complement the arr1 arr12 mutant. In addition, our results indicate that type-B ARR expression profiles in the plant, along with posttranscriptional regulation, play significant roles in modulating their contribution to cytokinin signaling.
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Bauer J, Reiss K, Veerabagu M, Heunemann M, Harter K, Stehle T. Structure-function analysis of Arabidopsis thaliana histidine kinase AHK5 bound to its cognate phosphotransfer protein AHP1. MOLECULAR PLANT 2013; 6:959-970. [PMID: 23132142 DOI: 10.1093/mp/sss126] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The multi-step phosphorelay (MSP) system defines a key signal transduction pathway in plants and many eukaryotes. In this system, external stimuli first lead to the activation of a histidine kinase, followed by transfer of a phosphoryl group from the receiver domain of the kinase (HK(RD)) to downstream, cytosolic phosphotransfer proteins (HPs). In order to establish the determinants of specificity for this signaling relay system, we have solved the first crystal structure of a plant HK(RD), AHK5(RD), in complex with one of its cognate HPs, AHP1. AHP1 binds AHK5(RD) via a prominent hydrogen bond docking ridge and a hydrophobic patch. These features are conserved among all AHP proteins, but differ significantly from other structurally characterized prokaryotic and eukaryotic HPs. Surface plasmon resonance experiments show that AHK5(RD) binds to AHP1-3 with similar, micromolar affinity, consistent with the transient nature of this signaling complex. Our correlation of structural and functional data provide the first insight, at the atomic level as well as with quantitative affinity data, into the molecular recognition events governing the MSP in plants.
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Affiliation(s)
- Johannes Bauer
- Interfaculty Institute of Biochemistry, University of Tübingen, D-72076 Tübingen, Germany
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31
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Amin M, Porter SL, Soyer OS. Split histidine kinases enable ultrasensitivity and bistability in two-component signaling networks. PLoS Comput Biol 2013; 9:e1002949. [PMID: 23505358 PMCID: PMC3591291 DOI: 10.1371/journal.pcbi.1002949] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 01/11/2013] [Indexed: 11/19/2022] Open
Abstract
Bacteria sense and respond to their environment through signaling cascades generally referred to as two-component signaling networks. These networks comprise histidine kinases and their cognate response regulators. Histidine kinases have a number of biochemical activities: ATP binding, autophosphorylation, the ability to act as a phosphodonor for their response regulators, and in many cases the ability to catalyze the hydrolytic dephosphorylation of their response regulator. Here, we explore the functional role of "split kinases" where the ATP binding and phosphotransfer activities of a conventional histidine kinase are split onto two distinct proteins that form a complex. We find that this unusual configuration can enable ultrasensitivity and bistability in the signal-response relationship of the resulting system. These dynamics are displayed under a wide parameter range but only when specific biochemical requirements are met. We experimentally show that one of these requirements, namely segregation of the phosphatase activity predominantly onto the free form of one of the proteins making up the split kinase, is met in Rhodobacter sphaeroides. These findings indicate split kinases as a bacterial alternative for enabling ultrasensitivity and bistability in signaling networks. Genomic analyses reveal that up 1.7% of all identified histidine kinases have the potential to be split and bifunctional.
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Affiliation(s)
- Munia Amin
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
- Systems Biology Program, College of Engineering, Computing and Mathematics, University of Exeter, Exeter, United Kingdom
| | - Steven L. Porter
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
- * E-mail: (SLP); (OSS)
| | - Orkun S. Soyer
- Systems Biology Program, College of Engineering, Computing and Mathematics, University of Exeter, Exeter, United Kingdom
- * E-mail: (SLP); (OSS)
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Determinants of specificity in two-component signal transduction. Curr Opin Microbiol 2013; 16:156-62. [PMID: 23352354 DOI: 10.1016/j.mib.2013.01.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 01/06/2013] [Accepted: 01/08/2013] [Indexed: 11/20/2022]
Abstract
Maintaining the faithful flow of information through signal transduction pathways is critical to the survival and proliferation of organisms. This problem is particularly challenging as many signaling proteins are part of large, paralogous families that are highly similar at the sequence and structural levels, increasing the risk of unwanted cross-talk. To detect environmental signals and process information, bacteria rely heavily on two-component signaling systems comprised of sensor histidine kinases and their cognate response regulators. Although most species encode dozens of these signaling pathways, there is relatively little cross-talk, indicating that individual pathways are well insulated and highly specific. Here, we review the molecular mechanisms that enforce this specificity. Further, we highlight recent studies that have revealed how these mechanisms evolve to accommodate the introduction of new pathways by gene duplication.
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Capra EJ, Perchuk BS, Ashenberg O, Seid CA, Snow HR, Skerker JM, Laub MT. Spatial tethering of kinases to their substrates relaxes evolutionary constraints on specificity. Mol Microbiol 2012; 86:1393-403. [DOI: 10.1111/mmi.12064] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Emily J. Capra
- Department of Biology; Massachusetts Institute of Technology; Cambridge; MA; 02139; USA
| | - Barrett S. Perchuk
- Department of Biology; Massachusetts Institute of Technology; Cambridge; MA; 02139; USA
| | - Orr Ashenberg
- Department of Biology; Massachusetts Institute of Technology; Cambridge; MA; 02139; USA
| | - Charlotte A. Seid
- Department of Biology; Massachusetts Institute of Technology; Cambridge; MA; 02139; USA
| | - Hana R. Snow
- Department of Biology; Massachusetts Institute of Technology; Cambridge; MA; 02139; USA
| | - Jeffrey M. Skerker
- Department of Bioengineering; University of California, Berkeley; Berkeley; CA; 94720; USA
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34
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Expanding the synthetic biology toolbox: engineering orthogonal regulators of gene expression. Curr Opin Biotechnol 2012; 23:689-94. [DOI: 10.1016/j.copbio.2011.12.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 12/14/2011] [Accepted: 12/15/2011] [Indexed: 01/06/2023]
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Capra EJ, Perchuk BS, Skerker JM, Laub MT. Adaptive mutations that prevent crosstalk enable the expansion of paralogous signaling protein families. Cell 2012; 150:222-32. [PMID: 22770222 PMCID: PMC3415470 DOI: 10.1016/j.cell.2012.05.033] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 04/23/2012] [Accepted: 05/18/2012] [Indexed: 11/30/2022]
Abstract
Orthologous proteins often harbor numerous substitutions, but whether these differences result from neutral or adaptive processes is usually unclear. To tackle this challenge, we examined the divergent evolution of a model bacterial signaling pathway comprising the kinase PhoR and its cognate substrate PhoB. We show that the specificity-determining residues of these proteins are typically under purifying selection but have, in α-proteobacteria, undergone a burst of diversification followed by extended stasis. By reversing mutations that accumulated in an α-proteobacterial PhoR, we demonstrate that these substitutions were adaptive, enabling PhoR to avoid crosstalk with a paralogous pathway that arose specifically in α-proteobacteria. Our findings demonstrate that duplication and the subsequent need to avoid crosstalk strongly influence signaling protein evolution. These results provide a concrete example of how system-wide insulation can be achieved postduplication through a surprisingly limited number of mutations. Our work may help explain the apparent ease with which paralogous protein families expanded in all organisms.
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Affiliation(s)
- Emily J Capra
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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36
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Stallforth P, Clardy J. Protein Evolution: When Two Become Three. Curr Biol 2012; 22:R685-7. [DOI: 10.1016/j.cub.2012.07.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Minato Y, Ueda T, Machiyama A, Shimada I, Iwaï H. Segmental isotopic labeling of a 140 kDa dimeric multi-domain protein CheA from Escherichia coli by expressed protein ligation and protein trans-splicing. JOURNAL OF BIOMOLECULAR NMR 2012; 53:191-207. [PMID: 22740268 PMCID: PMC3405243 DOI: 10.1007/s10858-012-9628-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 04/04/2012] [Indexed: 05/03/2023]
Abstract
Segmental isotopic labeling is a powerful labeling tool to facilitate NMR studies of larger proteins by not only alleviating the signal overlap problem but also retaining features of uniform isotopic labeling. Although two approaches, expressed protein ligation (EPL) and protein trans-splicing (PTS), have been mainly used for segmental isotopic labeling, there has been no single example in which both approaches have been directly used with an identical protein. Here we applied both EPL and PTS methods to a 140 kDa dimeric multi-domain protein E. coli CheA, and successfully produced the ligated CheA dimer by both approaches. In EPL approach, extensive optimization of the ligation sites and the conditions were required to obtain sufficient amount for an NMR sample of CheA, because CheA contains a dimer forming domain and it was not possible to achieve high reactant concentrations (1-5 mM) of CheA fragments for the ideal EPL condition, thereby resulting in the low yield of segmentally labelled CheA dimer. PTS approach sufficiently produced segmentally labeled ligated CheA in vivo as well as in vitro without extensive optimizations. This is presumably because CheA has self-contained domains connected with long linkers, accommodating a seven-residue mutation without loss of the function, which was introduced by PTS to achieve the high yield. PTS approach was less laborious than EPL approach for the routine preparation of segmentally-isotope labeled CheA dimer. Both approaches remain to be further developed for facilitating preparations of segmental isotope-labelled samples without extensive optimizations for ligation.
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Affiliation(s)
- Yuichi Minato
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Takumi Ueda
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Asako Machiyama
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Ichio Shimada
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
- Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, Aomi, Koto-ku, Tokyo, 135-0064 Japan
| | - Hideo Iwaï
- Research Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, P.O. Box 65, 00014 Helsinki, Finland
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Abstract
To exist in a wide range of environmental niches, bacteria must sense and respond to a variety of external signals. A primary means by which this occurs is through two-component signal transduction pathways, typically composed of a sensor histidine kinase that receives the input stimuli and then phosphorylates a response regulator that effects an appropriate change in cellular physiology. Histidine kinases and response regulators have an intrinsic modularity that separates signal input, phosphotransfer, and output response; this modularity has allowed bacteria to dramatically expand and diversify their signaling capabilities. Recent work has begun to reveal the molecular basis by which two-component proteins evolve. How and why do orthologous signaling proteins diverge? How do cells gain new pathways and recognize new signals? What changes are needed to insulate a new pathway from existing pathways? What constraints are there on gene duplication and lateral gene transfer? Here, we review progress made in answering these questions, highlighting how the integration of genome sequence data with experimental studies is providing major new insights.
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Affiliation(s)
- Emily J Capra
- Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA
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39
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Mo G, Zhou H, Kawamura T, Dahlquist FW. Solution structure of a complex of the histidine autokinase CheA with its substrate CheY. Biochemistry 2012; 51:3786-98. [PMID: 22494339 DOI: 10.1021/bi300147m] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In the bacterial chemotaxis two-component signaling system, the histidine-containing phosphotransfer domain (the "P1" domain) of CheA receives a phosphoryl group from the catalytic domain (P4) of CheA and transfers it to the cognate response regulator (RR) CheY, which is docked by the P2 domain of CheA. Phosphorylated CheY then diffuses into the cytoplasm and interacts with the FliM moiety of the flagellar motors, thereby modulating the direction of flagellar rotation. Structures of various histidine phosphotransfer domains (HPt) complexed with their cognate RR domains have been reported. Unlike the Escherichia coli chemotaxis system, however, these systems lack the additional domains dedicated to binding to the response regulators, and the interaction of an HPt domain with an RR domain in the presence of such a domain has not been examined on a structural basis. In this study, we used modern nuclear magnetic resonance techniques to construct a model for the interaction of the E. coli CheA P1 domain (HPt) and CheY (RR) in the presence of the CheY-binding domain, P2. Our results indicate that the presence of P2 may lead to a slightly different relative orientation of the HPt and RR domains versus those seen in such complex structures previously reported.
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Affiliation(s)
- Guoya Mo
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, USA
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40
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A specificity determinant for phosphorylation in a response regulator prevents in vivo cross-talk and modification by acetyl phosphate. Proc Natl Acad Sci U S A 2011; 108:20160-5. [PMID: 22128335 DOI: 10.1073/pnas.1113013108] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial two-component systems (TCSs) sense stimuli and transduce signals intracellularly through phosphotransfer between cognate histidine kinases (HKs) and response regulators (RRs) to alter gene expression or behavioral responses. Without high phosphotransfer specificity between cognate HKs and RRs, cross-phosphorylation or cross-talk between different TCSs may occur and diminish responses to appropriate stimuli. Some mechanisms to reduce cross-talk involve HKs controlling levels of cognate RR phosphorylation. Conceivably, some RRs may have evolved HK-independent strategies to insulate themselves from cross-talk with acetyl phosphate (AcP) or other small phosphodonor metabolites. Initial steps in flagellar biosynthesis in Campylobacter jejuni stimulate phosphotransfer from the FlgS HK to the FlgR RR to promote σ(54)-dependent flagellar gene expression. We discovered that the FlgR C-terminal domain (CTD), which commonly functions as a DNA-binding domain in the NtrC RR family, is a specificity determinant to limit in vivo cross-talk from AcP. FlgR lacking the CTD (FlgR(ΔCTD)) used FlgS or AcP as an in vivo phosphodonor and could be reprogrammed in ΔflgS mutants to respond to cellular nutritional status via AcP levels. Even though exclusive AcP-mediated activation of FlgR(ΔCTD) promoted WT flagellar gene expression, proper flagellar biosynthesis was impaired. We propose that the FlgR CTD prevents phosphotransfer from AcP so that FlgR is solely responsive to FlgS to promote proper flagellar gene expression and flagellation. In addition to mechanisms limiting cross-talk between noncognate HKs and RRs, our work suggests that RRs can possess domains that prevent in vivo cross-talk between RRs and the endogenous metabolite AcP to ensure signaling specificity.
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Schaller GE, Shiu SH, Armitage JP. Two-component systems and their co-option for eukaryotic signal transduction. Curr Biol 2011; 21:R320-30. [PMID: 21549954 DOI: 10.1016/j.cub.2011.02.045] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Two-component signaling pathways involve histidine kinases, response regulators, and sometimes histidine-containing phosphotransfer proteins. Prevalent in prokaryotes, these signaling elements have also been co-opted to meet the needs of signal transduction in eukaryotes such as fungi and plants. Here we consider the evolution of such regulatory systems, with a particular emphasis on the roles they play in signaling by the plant hormones cytokinin and ethylene, in phytochrome-mediated perception of light, and as integral components of the circadian clock.
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Affiliation(s)
- G Eric Schaller
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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42
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Vu A, Hamel DJ, Zhou H, Dahlquist FW. The structure and dynamic properties of the complete histidine phosphotransfer domain of the chemotaxis specific histidine autokinase CheA from Thermotoga maritima. JOURNAL OF BIOMOLECULAR NMR 2011; 51:49-55. [PMID: 21947914 PMCID: PMC3180615 DOI: 10.1007/s10858-011-9540-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Accepted: 06/22/2011] [Indexed: 05/31/2023]
Abstract
The bacterial histidine autokinase CheA contains a histidine phosphotransfer (Hpt) domain that accepts a phosphate from the catalytic domain and donates the phosphate to either target response regulator protein, CheY or CheB. The Hpt domain forms a helix-bundle structure with a conserved four-helix bundle motif and a variable fifth helix. Observation of two nearly equally populated conformations in the crystal structure of a Hpt domain fragment of CheA from Thermotoga maritima containing only the first four helices suggests more mobility in a tightly packed helix bundle structure than previously thought. In order to examine how the structures of Hpt domain homologs may differ from each other particularly in the conformation of the last helix, and whether an alternative conformation exists in the intact Hpt domain in solution, we have solved a high-resolution, solution structure of the CheA Hpt from T. maritima and characterized the backbone dynamics of this protein. The structure contains a four-helix bundle characteristic of histidine phosphotransfer domains. The position and orientation of the fifth helix resembles those in known Hpt domain crystal and solution structures in other histidine kinases. The alternative conformation that was reported in the crystal structure of the CheA Hpt from T. maritima missing the fifth helix is not detected in the solution structure, suggesting a role for the fifth helix in providing stabilizing forces to the overall structure.
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Affiliation(s)
- Anh Vu
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93103 USA
| | - Damon J. Hamel
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93103 USA
| | - Hongjun Zhou
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93103 USA
| | - Frederick W. Dahlquist
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93103 USA
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Bell CH, Aricescu AR, Jones EY, Siebold C. A dual binding mode for RhoGTPases in plexin signalling. PLoS Biol 2011; 9:e1001134. [PMID: 21912513 PMCID: PMC3166162 DOI: 10.1371/journal.pbio.1001134] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 07/20/2011] [Indexed: 11/19/2022] Open
Abstract
Plexins are cell surface receptors for the semaphorin family of cell guidance cues. The cytoplasmic region comprises a Ras GTPase-activating protein (GAP) domain and a RhoGTPase binding domain. Concomitant binding of extracellular semaphorin and intracellular RhoGTPase triggers GAP activity and signal transduction. The mechanism of this intricate regulation remains elusive. We present two crystal structures of the human Plexin-B1 cytoplasmic region in complex with a constitutively active RhoGTPase, Rac1. The structure of truncated Plexin-B1-Rac1 complex provides no mechanism for coupling RhoGTPase and Ras binding sites. On inclusion of the juxtamembrane helix, a trimeric structure of Plexin-B1-Rac1 complexes is stabilised by a second, novel, RhoGTPase binding site adjacent to the Ras site. Site-directed mutagenesis combined with cellular and biophysical assays demonstrate that this new binding site is essential for signalling. Our findings are consistent with a model in which extracellular and intracellular plexin clustering events combine into a single signalling output.
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Affiliation(s)
- Christian H. Bell
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - A. Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - E. Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
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Abstract
Rhodobacter sphaeroides is a metabolically diverse photosynthetic alphaproteobacterium found ubiquitously in soil and freshwater habitats. Here we present the annotated genome sequence of R. sphaeroides WS8N.
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45
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Schmöe K, Rogov V, Rogova N, Löhr F, Güntert P, Bernhard F, Dötsch V. Structural Insights into Rcs Phosphotransfer: The Newly Identified RcsD-ABL Domain Enhances Interaction with the Response Regulator RcsB. Structure 2011; 19:577-87. [DOI: 10.1016/j.str.2011.01.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 12/29/2010] [Accepted: 01/10/2011] [Indexed: 10/18/2022]
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Evolving a robust signal transduction pathway from weak cross-talk. Mol Syst Biol 2011; 6:452. [PMID: 21179024 PMCID: PMC3018164 DOI: 10.1038/msb.2010.105] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 11/05/2010] [Indexed: 11/15/2022] Open
Abstract
We have evolved a robust two-component signal transduction pathway from a sensor kinase (SK) and non-partner response regulator (RR) that show weak cross-talk in vitro and no detectable cross-talk in vivo in wild-type strains. The SK, CpxA, is bifunctional, with both kinase and phosphatase activities for its partner RR. We show that by combining a small number of mutations in CpxA that individually increase phosphorylation of the non-partner RR OmpR, phosphatase activity against phospho-OmpR emerges. The resulting circuit also becomes responsive to input signal to CpxA. The effects of combining these mutations in CpxA appear to reflect complex intragenic interactions between multiple sites in the protein. However, by analyzing a simple model of two-component signaling, we show that the behavior can be explained by a monotonic change in a single parameter controlling protein–protein interaction strength. The results suggest one possible mode of evolution for two-component systems with bifunctional SKs whereby the remarkable properties and competing reactions that characterize these systems can emerge by combining mutations of the same effect.
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48
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Choi K, Kim S. Building interacting partner predictors using co-varying residue pairs between histidine kinase and response regulator pairs of 48 bacterial two-component systems. Proteins 2011; 79:1118-31. [DOI: 10.1002/prot.22948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 11/03/2010] [Accepted: 11/05/2010] [Indexed: 11/11/2022]
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49
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Capra EJ, Perchuk BS, Lubin EA, Ashenberg O, Skerker JM, Laub MT. Systematic dissection and trajectory-scanning mutagenesis of the molecular interface that ensures specificity of two-component signaling pathways. PLoS Genet 2010; 6:e1001220. [PMID: 21124821 PMCID: PMC2991266 DOI: 10.1371/journal.pgen.1001220] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 10/26/2010] [Indexed: 12/04/2022] Open
Abstract
Two-component signal transduction systems enable bacteria to sense and respond to a wide range of environmental stimuli. Sensor histidine kinases transmit signals to their cognate response regulators via phosphorylation. The faithful transmission of information through two-component pathways and the avoidance of unwanted cross-talk require exquisite specificity of histidine kinase-response regulator interactions to ensure that cells mount the appropriate response to external signals. To identify putative specificity-determining residues, we have analyzed amino acid coevolution in two-component proteins and identified a set of residues that can be used to rationally rewire a model signaling pathway, EnvZ-OmpR. To explore how a relatively small set of residues can dictate partner selectivity, we combined alanine-scanning mutagenesis with an approach we call trajectory-scanning mutagenesis, in which all mutational intermediates between the specificity residues of EnvZ and another kinase, RstB, were systematically examined for phosphotransfer specificity. The same approach was used for the response regulators OmpR and RstA. Collectively, the results begin to reveal the molecular mechanism by which a small set of amino acids enables an individual kinase to discriminate amongst a large set of highly-related response regulators and vice versa. Our results also suggest that the mutational trajectories taken by two-component signaling proteins following gene or pathway duplication may be constrained and subject to differential selective pressures. Only some trajectories allow both the maintenance of phosphotransfer and the avoidance of unwanted cross-talk. Maintaining the specificity of signal transduction pathways is critical to the ability of cells to process information, make decisions, and regulate their behavior. Preventing cross-talk often relies predominantly on molecular recognition and a set of specificity-determining residues in cognate proteins. Identifying these residues and understanding how they dictate specificity is still a major challenge. Additionally, we have a rudimentary understanding of how specificity evolves, particularly after gene duplication events. We tackled these questions using two-component signaling proteins, the largest family of bacterial signaling proteins. Using analyses of amino acid coevolution, we pinpointed a set of specificity residues in histidine kinases and their cognate substrates. Then, using systematic mutagenesis, we characterized the complete set of intermediates between two different signaling systems, EnvZ/OmpR and RstA/RstB. The results demonstrate that specificity residues contribute unequally and, importantly, that some residues depend substantially on the identity of neighboring residues. We also demonstrate how the specificity of EnvZ/OmpR can be reprogrammed to match that of RstB/RstA through a series of individual substitutions without disrupting the kinase/regulator interaction. Notably, this property is not shared by all trajectories from EnvZ/OmpR to RstA/RstB, suggesting that the duplication/divergence process that likely produced these two pathways may have been fundamentally constrained.
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Affiliation(s)
- Emily J. Capra
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Barrett S. Perchuk
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Emma A. Lubin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Orr Ashenberg
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Jeffrey M. Skerker
- Department of Bioengineering, University of California Berkeley, Berkeley, California, United States of America
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Michael T. Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
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Scott KA, Porter SL, Bagg EAL, Hamer R, Hill JL, Wilkinson DA, Armitage JP. Specificity of localization and phosphotransfer in the CheA proteins of Rhodobacter sphaeroides. Mol Microbiol 2010; 76:318-30. [PMID: 20525091 DOI: 10.1111/j.1365-2958.2010.07095.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Specificity of protein-protein interactions plays a vital role in signal transduction. The chemosensory pathway of Rhodobacter sphaeroides comprises multiple homologues of chemotaxis proteins characterized in organisms such as Escherichia coli. Three CheA homologues are essential for chemotaxis in R. sphaeroides under laboratory conditions. These CheAs are differentially localized to two chemosensory clusters, one at the cell pole and one in the cytoplasm. The polar CheA, CheA(2), has the same domain structure as E. coli CheA and can phosphorylate all R. sphaeroides chemotaxis response regulators. CheA(3) and CheA(4) independently localize to the cytoplasmic cluster; each protein has a subset of the CheA domains, with CheA(3) phosphorylating CheA(4) together making a functional CheA protein. Interestingly, CheA(3)-P can only phosphorylate two response regulators, CheY(6) and CheB(2). R. sphaeroides CheAs exhibit two interesting differences in specificity: (i) the response regulators that they phosphorylate and (ii) the chemosensory cluster to which they localize. Using a domain-swapping approach we investigated the role of the P1 and P5 CheA domains in determining these specificities. We show that the P1 domain is sufficient to determine which response regulators will be phosphorylated in vitro while the P5 domain is sufficient to localize the CheAs to a specific chemosensory cluster.
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Affiliation(s)
- Kathryn A Scott
- Oxford Centre for Integrative Systems Biology, University of Oxford, Oxford, UK
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