1
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The role of polyproline motifs in the histidine kinase EnvZ. PLoS One 2018; 13:e0199782. [PMID: 29953503 PMCID: PMC6023141 DOI: 10.1371/journal.pone.0199782] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 06/13/2018] [Indexed: 12/20/2022] Open
Abstract
Although distinct amino acid motifs containing consecutive prolines (polyP) cause ribosome stalling, which necessitates recruitment of the translation elongation factor P (EF-P), they occur strikingly often in bacterial proteomes. For example, polyP motifs are found in more than half of all histidine kinases in Escherichia coli K-12, which raises the question of their role(s) in receptor function. Here we have investigated the roles of two polyP motifs in the osmosensor and histidine kinase EnvZ. We show that the IPPPL motif in the HAMP domain is required for dimerization of EnvZ. Moreover, replacement of the prolines in this motif by alanines disables the receptor’s sensor function. The second motif, VVPPA, which is located in the periplasmic domain, was found to be required for interaction with the modulator protein MzrA. Our study also reveals that polyP-dependent stalling has little effect on EnvZ levels. Hence, both polyP motifs in EnvZ are primarily involved in protein-protein interaction. Furthermore, while the first motif occurs in almost all EnvZ homologues, the second motif is only found in species that have MzrA, indicating co-evolution of the two proteins.
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2
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Fan X, Zhao J, Ren F, Wang Y, Feng Y, Ding L, Zhao L, Shang Y, Li J, Ni J, Jia B, Liu Y, Chang Z. Dimerization of p15RS mediated by a leucine zipper-like motif is critical for its inhibitory role on Wnt signaling. J Biol Chem 2018; 293:7618-7628. [PMID: 29618509 DOI: 10.1074/jbc.ra118.001969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/27/2018] [Indexed: 01/31/2023] Open
Abstract
We previously demonstrated that p15RS, a newly discovered tumor suppressor, inhibits Wnt/β-catenin signaling by interrupting the formation of β-catenin·TCF4 complex. However, it remains unclear how p15RS helps exert such an inhibitory effect on Wnt signaling based on its molecular structure. In this study, we reported that dimerization of p15RS is required for its inhibition on the transcription regulation of Wnt-targeted genes. We found that p15RS forms a dimer through a highly conserved leucine zipper-like motif in the coiled-coil terminus domain. In particular, residues Leu-248 and Leu-255 were identified as being responsible for p15RS dimerization, as mutation of these two leucines into prolines disrupted the homodimer formation of p15RS and weakened its suppression of Wnt signaling. Functional studies further confirmed that mutations of p15RS at these residues results in diminishment of its inhibition on cell proliferation and tumor formation. We therefore concluded that dimerization of p15RS governed by the leucine zipper-like motif is critical for its inhibition of Wnt/β-catenin signaling and tumorigenesis.
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Affiliation(s)
- Xuanzi Fan
- From the State Key Laboratory of Membrane Biology, School of Medicine and.,the School of Life Sciences, Tsinghua University, Beijing 100084
| | - Juan Zhao
- From the State Key Laboratory of Membrane Biology, School of Medicine and
| | - Fangli Ren
- From the State Key Laboratory of Membrane Biology, School of Medicine and
| | - Yinyin Wang
- From the State Key Laboratory of Membrane Biology, School of Medicine and
| | - Yarui Feng
- From the State Key Laboratory of Membrane Biology, School of Medicine and
| | - Lidan Ding
- From the State Key Laboratory of Membrane Biology, School of Medicine and
| | - Linpeng Zhao
- the Department of Cell Biology, College of Life Sciences, Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Beijing Normal University, Beijing 100875
| | - Yu Shang
- the Department of Cell Biology, College of Life Sciences, Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Beijing Normal University, Beijing 100875
| | - Jun Li
- the Institute of Immunology, PLA, The Third Military Medical University, Chongqing 400038, and
| | - Jianquan Ni
- From the State Key Laboratory of Membrane Biology, School of Medicine and
| | - Baoqing Jia
- the Department of General Surgery/Pathology, Chinese PLA General Hospital, Beijing 100853, China
| | - Yule Liu
- the School of Life Sciences, Tsinghua University, Beijing 100084
| | - Zhijie Chang
- From the State Key Laboratory of Membrane Biology, School of Medicine and
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3
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Hwang E, Cheong HK, Kim SY, Kwon O, Blain KY, Choe S, Yeo KJ, Jung YW, Jeon YH, Cheong C. Crystal structure of the EnvZ periplasmic domain with CHAPS. FEBS Lett 2017; 591:1419-1428. [DOI: 10.1002/1873-3468.12658] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/11/2017] [Accepted: 04/13/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Eunha Hwang
- Division of Bioconvergence Analysis; Korea Basic Science Institute (KBSI); Chungbuk Korea
| | - Hae-Kap Cheong
- Division of Bioconvergence Analysis; Korea Basic Science Institute (KBSI); Chungbuk Korea
| | - Sang-Yoon Kim
- Synthetic Biology and Bioengineering Research Center; Korea Research Institute of Bioscience & Biotechnology (KRIBB); Daejeon Korea
| | - Ohsuk Kwon
- Synthetic Biology and Bioengineering Research Center; Korea Research Institute of Bioscience & Biotechnology (KRIBB); Daejeon Korea
| | - Katherine Y. Blain
- Qualcomm Institute; University of California San Diego; San Diego CA USA
| | - Senyon Choe
- Qualcomm Institute; University of California San Diego; San Diego CA USA
| | - Kwon Joo Yeo
- College of Pharmacy; Korea University; Sejong Korea
| | | | | | - Chaejoon Cheong
- Division of Bioconvergence Analysis; Korea Basic Science Institute (KBSI); Chungbuk Korea
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4
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Heininger A, Yusuf R, Lawrence RJ, Draheim RR. Identification of transmembrane helix 1 (TM1) surfaces important for EnvZ dimerisation and signal output. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1868-75. [PMID: 27155567 DOI: 10.1016/j.bbamem.2016.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 04/12/2016] [Accepted: 05/03/2016] [Indexed: 02/06/2023]
Abstract
The Escherichia coli sensor kinase EnvZ modulates porin expression in response to various stimuli, including extracellular osmolarity, the presence of procaine and interaction with an accessory protein, MzrA. Two major outer membrane porins, OmpF and OmpC, act as passive diffusion-limited pores that allow compounds, including certain classes of antibiotics such as β-lactams and fluoroquinolones, to enter the bacterial cell. Even though the mechanisms by which EnvZ detects and processes the presence of various stimuli are a fundamental component of microbial physiology, they are not yet fully understood. Here, we assess the role of TM1 during signal transduction in response to the presence of extracellular osmolarity. Various mechanisms of transmembrane communication have been proposed including rotation of individual helices within the transmembrane domain, dynamic movement of the membrane-distal portion of the cytoplasmic domain and regulated intra-protein unfolding. To assess these possibilities, we have created a library of single-Cys-containing EnvZ proteins in order to facilitate sulfhydryl-reactivity experimentation. Our results demonstrate that the major TM1-TM1' interface falls along a single surface consisting of residue positions 19, 23, 26, 30 and 34. In addition, we show that Cys substitutions within the N- and C-terminal regions of TM1 result in drastic changes to EnvZ signal output. Finally, we demonstrate that core residues within TM1 are responsible for both TM1 dimerisation and maintenance of steady-state signal output. Overall, our results suggest that no major rearrangement of the TM1-TM1' interface occurs during transmembrane communication in response to extracellular osmolarity. We conclude by discussing these results within the frameworks of several proposed models for transmembrane communication.
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Affiliation(s)
- Annika Heininger
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, D-60438 Frankfurt, Germany.
| | - Rahmi Yusuf
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, England, UK.
| | - Robert J Lawrence
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, England, UK.
| | - Roger R Draheim
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, England, UK; Institute of Biomedical and Biomolecular Science, University of Portsmouth, Portsmouth PO1 2DT, England, UK.
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5
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The ArcB leucine zipper domain is required for proper ArcB signaling. PLoS One 2012; 7:e38187. [PMID: 22666479 PMCID: PMC3364231 DOI: 10.1371/journal.pone.0038187] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 05/01/2012] [Indexed: 01/01/2023] Open
Abstract
The Arc two-component system modulates the expression of numerous genes in response to respiratory growth conditions. This system comprises ArcA as the response regulator and ArcB as the sensor kinase. ArcB is a tripartite histidine kinase whose activity is regulated by the oxidation of two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here, we report that the ArcB protein segment covering residues 70-121, fulfills the molecular characteristics of a leucine zipper containing coiled coil structure. Also, mutational analyses of this segment reveal three different phenotypical effects to be distributed along the coiled coil structure of ArcB, demonstrating that this motif is essential for proper ArcB signaling.
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6
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Leatham-Jensen MP, Frimodt-Møller J, Adediran J, Mokszycki ME, Banner ME, Caughron JE, Krogfelt KA, Conway T, Cohen PS. The streptomycin-treated mouse intestine selects Escherichia coli envZ missense mutants that interact with dense and diverse intestinal microbiota. Infect Immun 2012; 80:1716-27. [PMID: 22392928 PMCID: PMC3347456 DOI: 10.1128/iai.06193-11] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/16/2012] [Indexed: 01/07/2023] Open
Abstract
Previously, we reported that the streptomycin-treated mouse intestine selected nonmotile Escherichia coli MG1655 flhDC deletion mutants of E. coli MG1655 with improved colonizing ability that grow 15% faster in vitro in mouse cecal mucus and 15 to 30% faster on sugars present in mucus (M. P. Leatham et al., Infect. Immun. 73:8039-8049, 2005). Here, we report that the 10 to 20% remaining motile E. coli MG1655 are envZ missense mutants that are also better colonizers of the mouse intestine than E. coli MG1655. One of the flhDC mutants, E. coli MG1655 ΔflhD, and one of the envZ missense mutants, E. coli MG1655 mot-1, were studied further. E. coli MG1655 mot-1 is more resistant to bile salts and colicin V than E. coli MG1655 ΔflhD and grows ca. 15% slower in vitro in mouse cecal mucus and on several sugars present in mucus compared to E. coli MG1655 ΔflhD but grows 30% faster on galactose. Moreover, E. coli MG1655 mot-1 and E. coli MG1655 ΔflhD appear to colonize equally well in one intestinal niche, but E. coli MG1655 mot-1 appears to use galactose to colonize a second, smaller intestinal niche either not colonized or colonized poorly by E. coli MG1655 ΔflhD. Evidence is also presented that E. coli MG1655 is a minority member of mixed bacterial biofilms in the mucus layer of the streptomycin-treated mouse intestine. We offer a hypothesis, which we call the "Restaurant" hypothesis, that explains how nutrient acquisition in different biofilms comprised of different anaerobes can account for our results.
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Affiliation(s)
- Mary P. Leatham-Jensen
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Jakob Frimodt-Møller
- Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen S, Denmark
| | - Jimmy Adediran
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Matthew E. Mokszycki
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Megan E. Banner
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Joyce E. Caughron
- Department of Botany and Microbiology, University of Oklahoma, Norman, Okloahoma, USA
| | - Karen A. Krogfelt
- Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen S, Denmark
| | - Tyrrell Conway
- Department of Botany and Microbiology, University of Oklahoma, Norman, Okloahoma, USA
| | - Paul S. Cohen
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
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7
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Crozat E, Hindré T, Kühn L, Garin J, Lenski RE, Schneider D. Altered regulation of the OmpF porin by Fis in Escherichia coli during an evolution experiment and between B and K-12 strains. J Bacteriol 2011; 193:429-40. [PMID: 21097626 PMCID: PMC3019833 DOI: 10.1128/jb.01341-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 11/08/2010] [Indexed: 12/19/2022] Open
Abstract
The phenotypic plasticity of global regulatory networks provides bacteria with rapid acclimation to a wide range of environmental conditions, while genetic changes in those networks provide additional flexibility as bacteria evolve across long time scales. We previously identified mutations in the global regulator-encoding gene fis that enhanced organismal fitness during a long-term evolution experiment with Escherichia coli. To gain insight into the effects of these mutations, we produced two-dimensional protein gels with strains carrying different fis alleles, including a beneficial evolved allele and one with an in-frame deletion. We found that Fis controls the expression of the major porin-encoding gene ompF in the E. coli B-derived ancestral strain used in the evolution experiment, a relationship that has not been described before. We further showed that this regulatory connection evolved over two different time scales, perhaps explaining why it was not observed before. On the longer time scale, we showed that this regulation of ompF by Fis is absent from the more widely studied K-12 strain and thus is specific to the B strain. On a shorter time scale, this regulatory linkage was lost during 20,000 generations of experimental evolution of the B strain. Finally, we mapped the Fis binding sites in the ompF regulatory region, and we present a hypothetical model of ompF expression that includes its other known regulators.
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Affiliation(s)
- Estelle Crozat
- Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier, Grenoble 1, BP 170, F-38042 Grenoble Cedex 9, France, CEA, DSV, iRTSV, Laboratoire d'Etude de la Dynamique des Protéomes, INSERM, U880, F-38042 Grenoble Cedex 9, France, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Thomas Hindré
- Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier, Grenoble 1, BP 170, F-38042 Grenoble Cedex 9, France, CEA, DSV, iRTSV, Laboratoire d'Etude de la Dynamique des Protéomes, INSERM, U880, F-38042 Grenoble Cedex 9, France, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Lauriane Kühn
- Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier, Grenoble 1, BP 170, F-38042 Grenoble Cedex 9, France, CEA, DSV, iRTSV, Laboratoire d'Etude de la Dynamique des Protéomes, INSERM, U880, F-38042 Grenoble Cedex 9, France, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Jérome Garin
- Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier, Grenoble 1, BP 170, F-38042 Grenoble Cedex 9, France, CEA, DSV, iRTSV, Laboratoire d'Etude de la Dynamique des Protéomes, INSERM, U880, F-38042 Grenoble Cedex 9, France, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Richard E. Lenski
- Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier, Grenoble 1, BP 170, F-38042 Grenoble Cedex 9, France, CEA, DSV, iRTSV, Laboratoire d'Etude de la Dynamique des Protéomes, INSERM, U880, F-38042 Grenoble Cedex 9, France, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Dominique Schneider
- Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier, Grenoble 1, BP 170, F-38042 Grenoble Cedex 9, France, CEA, DSV, iRTSV, Laboratoire d'Etude de la Dynamique des Protéomes, INSERM, U880, F-38042 Grenoble Cedex 9, France, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
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8
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Transmembrane polar interactions are required for signaling in the Escherichia coli sensor kinase PhoQ. Proc Natl Acad Sci U S A 2010; 107:8141-6. [PMID: 20404199 DOI: 10.1073/pnas.1003166107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PhoQ is the transmembrane sensor histidine kinase of the bacterial phoPQ two-component system, which detects and responds to divalent cations and to antimicrobial peptides, and can trigger virulence. Despite their ubiquitous importance in bacterial signaling, the structure and mechanism of the sensor kinases are not fully understood. In particular, the mechanism by which the signal is propagated through the transmembrane (TM) region remains unclear. We have identified a critical asparagine residue in the second TM helix of PhoQ. Replacement of this Asn202 with a variety of hydrophobic amino acids results in a protein that is blind to signal, fails to activate transcription of PhoQ-dependent genes, and abrogates transcription when coexpressed with wild-type PhoQ. Analysis of other two-component kinase sequences indicated that many such proteins contain similarly conserved polar residues, and the structure of one such domain shows a polar residue proximal to an extended cavity near the center of the TM bundle. We therefore examined the role of Asn202 in PhoQ. Our analysis indicated that its kinase function is dependent on the polarity of Asn202, rather than its precise structure or position in the TM region; it can be displaced up or down one turn of TM helix 2, or even moved to the adjacent TM helix 1. The presence of polar TM amino acids among many diverse sensor kinases suggest a widespread mechanism of two-component signal transduction; we speculate that they might stabilize underpacked water-containing cavities that can accommodate conformational changes required for switching from phosphatase to kinase-competent conformations.
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9
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Smirnova AV, Braun Y, Ullrich MS. Site-directed mutagenesis of the temperature-sensing histidine protein kinase CorS from Pseudomonas syringae. FEMS Microbiol Lett 2008; 283:231-8. [DOI: 10.1111/j.1574-6968.2008.01179.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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10
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Determination of the physiological dimer interface of the PhoQ sensor domain. J Mol Biol 2008; 379:656-65. [PMID: 18468622 DOI: 10.1016/j.jmb.2008.04.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/02/2008] [Accepted: 04/03/2008] [Indexed: 11/22/2022]
Abstract
PhoQ is the transmembrane sensor kinase of the phoPQ two-component system, which detects and responds to divalent cations and antimicrobial peptides and can trigger bacterial virulence. Despite their ubiquity and importance in bacterial signaling, the structure and molecular mechanism of the sensor kinases is not fully understood. Frequently, signals are transmitted from a periplasmic domain in these proteins to the cytoplasmic kinase domains via an extended dimeric interface, and the PhoQ protein would appear to follow this paradigm. However, the isolated truncated periplasmic domain of PhoQ dimerizes poorly, so it has been difficult to distinguish the relevant interface in crystal structures of the PhoQ periplasmic domain. Thus, to determine the arrangement of the periplasmic domains of Escherichia coli PhoQ in the physiological homodimer, disulfide-scanning mutagenesis was used. Single cysteine substitutions were introduced along the N-terminal helix of the periplasmic region, and the degree of cross-linking in each protein variant was determined by Western blotting and immunodetection. The results were subjected to periodicity analysis to generate a profile that provides information concerning the C(beta) distances between corresponding residues at the interface. This profile, together with a rigid-body search procedure, side-chain placement, and energy minimization, was used to build a model of the dimer arrangement. The final model proved to be highly compatible with one of the PhoQ crystal structures, 3BQ8, indicating that 3BQ8 is representative of the physiological arrangement. The model of the periplasmic region is also compatible with a full-length PhoQ protein in which a four-helix bundle forms in the membrane. The membrane four-helix bundle has been proposed for other sensor kinases and is thought to have a role in the mechanism of signal transduction; our model supports the idea that signaling through a membrane four-helix bundle is a widespread mechanism in the transmembrane sensor kinases.
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11
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Mascher T, Helmann JD, Unden G. Stimulus perception in bacterial signal-transducing histidine kinases. Microbiol Mol Biol Rev 2007; 70:910-38. [PMID: 17158704 PMCID: PMC1698512 DOI: 10.1128/mmbr.00020-06] [Citation(s) in RCA: 505] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Two-component signal-transducing systems are ubiquitously distributed communication interfaces in bacteria. They consist of a histidine kinase that senses a specific environmental stimulus and a cognate response regulator that mediates the cellular response, mostly through differential expression of target genes. Histidine kinases are typically transmembrane proteins harboring at least two domains: an input (or sensor) domain and a cytoplasmic transmitter (or kinase) domain. They can be identified and classified by virtue of their conserved cytoplasmic kinase domains. In contrast, the sensor domains are highly variable, reflecting the plethora of different signals and modes of sensing. In order to gain insight into the mechanisms of stimulus perception by bacterial histidine kinases, we here survey sensor domain architecture and topology within the bacterial membrane, functional aspects related to this topology, and sequence and phylogenetic conservation. Based on these criteria, three groups of histidine kinases can be differentiated. (i) Periplasmic-sensing histidine kinases detect their stimuli (often small solutes) through an extracellular input domain. (ii) Histidine kinases with sensing mechanisms linked to the transmembrane regions detect stimuli (usually membrane-associated stimuli, such as ionic strength, osmolarity, turgor, or functional state of the cell envelope) via their membrane-spanning segments and sometimes via additional short extracellular loops. (iii) Cytoplasmic-sensing histidine kinases (either membrane anchored or soluble) detect cellular or diffusible signals reporting the metabolic or developmental state of the cell. This review provides an overview of mechanisms of stimulus perception for members of all three groups of bacterial signal-transducing histidine kinases.
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Affiliation(s)
- Thorsten Mascher
- Department of General Microbiology, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
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12
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Malpica R, Sandoval GRP, Rodríguez C, Franco B, Georgellis D. Signaling by the arc two-component system provides a link between the redox state of the quinone pool and gene expression. Antioxid Redox Signal 2006; 8:781-95. [PMID: 16771670 DOI: 10.1089/ars.2006.8.781] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The Arc two-component system is a complex signal transduction system that plays a key role in regulating energy metabolism at the level of transcription in bacteria. This system comprises the ArcB protein, a tripartite membrane-associated sensor kinase, and the ArcA protein, a typical response regulator. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates the expression of its target operons. Under aerobic conditions, ArcB acts as a phosphatase that catalyzes the dephosphorylation of ArcA-P and thereby releasing its transcriptional regulation. The events for Arc signaling, including signal reception and kinase regulation, signal transmission, amplification, as well as signal output and decay are discussed.
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Affiliation(s)
- Roxana Malpica
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City, México
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13
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Krantz M, Becit E, Hohmann S. Comparative analysis of HOG pathway proteins to generate hypotheses for functional analysis. Curr Genet 2006; 49:152-65. [PMID: 16468041 DOI: 10.1007/s00294-005-0039-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2005] [Revised: 09/07/2005] [Accepted: 09/24/2005] [Indexed: 12/17/2022]
Abstract
Comparative genomics allows comparison of different proteins that execute presumably identical functions in different organisms. In contrast to paralogues, orthologues per definition perform the same function and interact with the same partners and, consequently, should display conservation in all these properties. We have employed 20 fungal genomes to analyse key components of the high osmolarity glycerol signalling pathway of Saccharomyces cerevisiae. Among the proteins scrutinised are a complete phosphotransfer module, a MAP kinase, two scaffold proteins, one of which is also a MAPKK, and two transcription factors. Sequence alignments, domain structure and size analysis, combined with the rich information available in the literature, allowed us to probe previous structural and functional studies and to generate hypotheses for future experimental studies. Although certain domains are too highly conserved across fungal species for meaningful comparative studies, others, like interaction domains, can be studied in closely related species. Moreover, putative functionally relevant sites for protein modifications can be identified in such comparative studies. We provide several relevant examples and present a number of previously un(der)characterised domains of potential functional significance in osmosensing and signal transduction. We propose that any functional protein analysis in fungi should make use of the unique resource that fungal genome sequences offer.
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Affiliation(s)
- Marcus Krantz
- Department for Cell and Molecular Biology, Göteborg University, Box 462, 40530, Göteborg, Sweden
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14
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Khorchid A, Inouye M, Ikura M. Structural characterization of Escherichia coli sensor histidine kinase EnvZ: the periplasmic C-terminal core domain is critical for homodimerization. Biochem J 2005; 385:255-64. [PMID: 15357641 PMCID: PMC1134694 DOI: 10.1042/bj20041125] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 08/11/2004] [Accepted: 09/09/2004] [Indexed: 11/17/2022]
Abstract
Escherichia coli EnvZ is a membrane sensor histidine kinase that plays a pivotal role in cell adaptation to changes in extracellular osmolarity. Although the cytoplasmic histidine kinase domain of EnvZ has been extensively studied, both biochemically and structurally, little is known about the structure of its periplasmic domain, which has been implicated in the mechanism underlying its osmosensing function. In the present study, we report the biochemical and biophysical characterization of the periplasmic region of EnvZ (Ala38-Arg162). This region was found to form a dimer in solution, and to consist of two well-defined domains: an N-terminal a-helical domain and a C-terminal core domain (Glu83-Arg162) containing both a-helical and b-sheet secondary structures. Our pull-down assays and analytical ultracentrifugation analysis revealed that dimerization of the periplasmic region is highly sensitive to the presence of CHAPS, but relatively insensitive to salt concentration, thus suggesting the significance of hydrophobic interactions between the homodimeric subunits. Periplasmic homodimerization is mediated predominantly by the C-terminal core domain, while a regulatory function may be attributed mainly to the N-terminal a-helical domain, whose mutations have been shown previously to produce a high-osmolarity phenotype.
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Affiliation(s)
- Ahmad Khorchid
- *Division of Molecular and Structural Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9
| | - Masayori Inouye
- †Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, U.S.A
| | - Mitsuhiko Ikura
- *Division of Molecular and Structural Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9
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Wright JS, Lyon GJ, George EA, Muir TW, Novick RP. Hydrophobic interactions drive ligand-receptor recognition for activation and inhibition of staphylococcal quorum sensing. Proc Natl Acad Sci U S A 2004; 101:16168-73. [PMID: 15528279 PMCID: PMC528941 DOI: 10.1073/pnas.0404039101] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Indexed: 11/18/2022] Open
Abstract
Two-component systems represent the most widely used signaling paradigm in living organisms. Encoding the prototypical two-component system in Gram-positive bacteria, the staphylococcal agr (accessory gene regulator) operon uses a polytopic receptor, AgrC, activated by an autoinducing peptide (AIP), to coordinate quorum sensing with the global synthesis of virulence factors. The agr locus has undergone evolutionary divergence, resulting in the formation of several distinct inter- and intraspecies specificity groups, such that most cross-group AIP-receptor interactions are mutually inhibitory. We have exploited this natural diversity by constructing and analyzing AgrC chimeras generated by exchange of intradomain segments between receptors of different agr groups. Functional chimeras fell into three general classes: receptors with broadened specificity, receptors with tightened specificity, and receptors that lack activation specificity. Testing of these chimeric receptors against a battery of AIP analogs localized the primary ligand recognition site to the receptor distal subdomain and revealed that the AIPs bind primarily to a putative hydrophobic pocket in the receptor. This binding is mediated by a highly conserved hydrophobic patch on the AIPs and is an absolute requirement for interactions in self-activation and cross-inhibition of the receptors. It is suggested that this recognition scheme provides the fundamental basis for agr activation and interference.
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Affiliation(s)
- Jesse S Wright
- Molecular Pathogenesis Program and Department of Microbiology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
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16
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Enz S, Brand H, Orellana C, Mahren S, Braun V. Sites of interaction between the FecA and FecR signal transduction proteins of ferric citrate transport in Escherichia coli K-12. J Bacteriol 2003; 185:3745-52. [PMID: 12813067 PMCID: PMC161571 DOI: 10.1128/jb.185.13.3745-3752.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription of the fecABCDE ferric citrate transport genes of Escherichia coli K-12 is initiated by a signaling cascade from the cell surface into the cytoplasm. FecR receives the signal in the periplasm from the outer membrane protein FecA loaded with ferric citrate, transmits the signal across the cytoplasmic membrane, and converts FecI in the cytoplasm to an active sigma factor. In this study, it was shown through the use of a bacterial two-hybrid system that, in the periplasm, the C-terminal FecR(237-317) fragment interacts with the N-terminal FecA(1-79) fragment. In the same C-terminal region, amino acid residues important for the interaction of FecR with FecA were identified by random and site-directed mutagenesis. They were preferentially located in and around a leucine motif (residues 247 to 268) which was found to be highly conserved in FecR-like proteins. The degree of residual binding of FecR mutant proteins to FecA was correlated with the degree of transcription initiation in response to ferric citrate in the culture medium. Three randomly generated inactive FecR mutants, FecR(L254E), FecR(L269G), and FecR(F284L), were suppressed to different degrees by the mutants FecA(G39R) and FecR(D43E). One FecR mutant, FecR (D138E, V197A), induced fecA promoter-directed transcription constitutively in the absence of ferric citrate and bound more strongly than wild-type FecR to FecA. The data showed that FecR interacts in the periplasm with FecA to confer ferric citrate-induced transcription of the fec transport genes and identified sites in FecR and FecA that are important for signal transduction.
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Affiliation(s)
- Sabine Enz
- Mikrobiologie/Membranphysiologie, Universität Tübingen, D-72076 Tübingen, Germany
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17
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Tamura T, Hara K, Yamaguchi Y, Koizumi N, Sano H. Osmotic stress tolerance of transgenic tobacco expressing a gene encoding a membrane-located receptor-like protein from tobacco plants. PLANT PHYSIOLOGY 2003; 131:454-62. [PMID: 12586870 PMCID: PMC166822 DOI: 10.1104/pp.102.011007] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2002] [Revised: 08/07/2002] [Accepted: 10/16/2002] [Indexed: 05/17/2023]
Abstract
Tobacco (Nicotiana tabacum) genes regulated during the early stage of responses to wounding were screened by a modified fluorescence differential display method. Among 28 genes initially identified, a particular clone designated NtC7 was subjected to further analysis. Its transcripts were found to accumulate rapidly and transiently within 1 h upon treatments with not only wounding but also salt and osmotic stresses. However, jasmonic and abscisic acids and ethylene did not effectively induce NtC7 transcripts. Amino acid sequence analysis suggested NtC7 to be a new type of transmembrane protein that belongs to the receptor-like protein family, and a membrane location was confirmed in onion (Allium cepa) epidermis cells transiently expressing an NtC7-green fluorescent protein fusion protein. Seeds of transgenic tobacco overexpressing NtC7 normally germinated and grew in the presence of 500 mM mannitol, but not in the presence of 220 mM sodium chloride or 60 mM lithium chloride. Cuttings of mature transgenic leaf exhibited a marked tolerance upon treatment with 500 mM mannitol for 12 h, at which concentration wild-type counterparts were seriously damaged. These results suggested that NtC7 predominantly functions in maintenance of osmotic adjustment independently of ion homeostasis.
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Affiliation(s)
- Takashi Tamura
- Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630-0192, Japan
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18
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Mikami K, Kanesaki Y, Suzuki I, Murata N. The histidine kinase Hik33 perceives osmotic stress and cold stress in Synechocystis sp PCC 6803. Mol Microbiol 2002; 46:905-15. [PMID: 12421299 DOI: 10.1046/j.1365-2958.2002.03202.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The stress imposed on living organisms by hyperosmotic conditions and low temperature appears to be perceived via changes in the physical state of membrane lipids. We compared genome-wide patterns of transcription between wild-type Synechocystis sp. PCC 6803 and cells with a mutation in the histidine kinase Hik33 using a DNA microarray. Our results indicated that Hik33 regulated the expression of both osmostress-inducible and cold-inducible genes. The respective genes that were regulated by Hik33 under hyperosmotic and low-temperature conditions were, for the most part, different from one another. However, Hik33 also regulated the expression of a set of genes whose expression was induced both by osmotic stress and by cold stress. These results indicate that Hik33 is involved in responses to osmotic stress and low-temperature stress but that the mechanisms of the responses differ.
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Affiliation(s)
- Koji Mikami
- Department of Regulation, National Institute for Basic Biology, Okazaki, Japan
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19
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Rangaswamy V, Bender CL. Phosphorylation of CorS and CorR, regulatory proteins that modulate production of the phytotoxin coronatine in Pseudomonas syringae. FEMS Microbiol Lett 2000; 193:13-8. [PMID: 11094272 DOI: 10.1111/j.1574-6968.2000.tb09395.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Production of the phytotoxin coronatine (COR) in Pseudomonas syringae pv. glycinea PG4180 is controlled by a modified two-component regulatory system consisting of three genes, corR, corP, and corS. CorR and CorP show similarity to response regulators, and CorS is related to histidine protein kinases that function as environmental sensors. In this study, CorR, CorP and the cytoplasmic portion of CorS, designated CorSDelta, were overproduced in P. syringae as translational fusions to the maltose-binding protein and purified by affinity chromatography. Autophosphorylation of CorSDelta was demonstrated when [gamma-(32)P]ATP was used as a phosphodonor. Phosphorylated CorSDelta (CorSDelta approximately P) was stable under basic conditions, but extremely sensitive when the pH was reduced, which is consistent with phosphorylation at a histidine residue. CorSDelta approximately P transferred its phosphoryl group to CorR but not to CorP, which correlates with the presence of a receiver aspartate residue in the former but not the latter protein. These results indicate that CorS functions as a histidine protein kinase and transphosphorylates CorR, a positive activator of cor gene transcription.
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Affiliation(s)
- V Rangaswamy
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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20
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Matsubara M, Kitaoka SI, Takeda SI, Mizuno T. Tuning of the porin expression under anaerobic growth conditions by his-to-Asp cross-phosphorelay through both the EnvZ-osmosensor and ArcB-anaerosensor in Escherichia coli. Genes Cells 2000; 5:555-69. [PMID: 10947842 DOI: 10.1046/j.1365-2443.2000.00347.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Widespread bacterial signal transduction circuits are generally referred to as 'two-component systems' or 'histidine (His)-to-aspartate (Asp) phosphorelays.' In Escherichia coli, as many as 30 distinct His-to-Asp phosphorelay signalling pathways operate in response to a wide variety of environmental stimuli, such as medium osmolarity and anaerobiosis. In this regard, it is of interest whether or not some of them together constitute a network of signalling pathways through a physiologically relevant mechanism (often referred to as 'cross-regulation'). We have addressed this issue, with special reference to the osmo-responsive EnvZ and anaero-responsive ArcB phosphorelay signalling pathways in E. coli. RESULTS Under standard aerobic growth conditions, it is well known that the osmoregulatory profile of the outer membrane porins (OmpC and OmpF) is mainly regulated by the EnvZ-OmpR phosphorelay system in response to medium osmolarity. In this study, it was found that, under anaerobic growth conditions, E. coli cells exhibit a markedly altered expression profile of OmpC and OmpF This profile was significantly different from that observed for the cells grown aerobically. Results from extensive genetic studies showed that, under such anaerobic growth conditions, the arcB gene encoding the anaero-sensory His-kinase appears to be an auxiliary genetic determinant that regulates the expression profile of porins. We then provided several lines of in vivo and in vitro evidence, which taken together, supported the following conclusions. CONCLUSIONS Under anaerobic growth conditions, porin expression is tuned not only by the authentic osmo-resposive EnvZ sensor, but also by the anaero-responsive ArcB sensor, in an OmpR-dependent manner. It is suggested that such ArcB-mediated cross-regulation plays a physiological role by integrating anaerobic respiratory signals into the porin regulation in E. coli anaerobiosis. The proposed model is a clear example of the interplay of two distinct His-to-Asp phosphorelay signalling pathways.
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Affiliation(s)
- M Matsubara
- Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
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21
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Moenkemann H, Labudova O, Yeghiazarian K, Rink H, Hoeger H, Lubec G. Evidence that taurine modulates osmoregulation by modification of osmolarity sensor protein ENVZ--expression. Amino Acids 2000; 17:347-55. [PMID: 10707764 DOI: 10.1007/bf01361660] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although the involvement of taurine in osmoregulation is well-documented and widely accepted, no detailed mechanism for this function has been reported so far. We used subtractive hybridization to study mRNA steady state levels of genes up- or downregulated by taurine. Rats were fed taurine 100 mg/kg body weight per day for a period of three days and hearts (total ventricular tissue) of experimental animals and controls were pooled and used for mRNA extraction. mRNAs from two groups were used for subtractive hybridization. Clones of the subtractive library were sequenced and the obtained sequences were identified by gen bank assignment. Two clones were found to contain sequences which could be assigned to the osmolarity sensor protein envZ, showing homologies of 61 and 65%. EnvZ is an inner membrane protein in bacteria, important for osmosensing and required for porine gene regulation. It undergoes autophosphorylation and subsequently phosphorylates OmpR, which in turn binds to the porine (outer membrane protein) promoters to regulate the expression of OmpF and OmpC, major outer membrane porines. This is the first report of an osmosensing mechanism in the mammalian system, which was described in bacteria only. Furthermore, we are assigning a tentative role for taurine in the osmoregulatory process by modifying the expression of the osmoregulatory sensor protein ENVZ.
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Affiliation(s)
- H Moenkemann
- Department of Pediatrics, University of Vienna, Austria
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22
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Suzuki I, Los DA, Kanesaki Y, Mikami K, Murata N. The pathway for perception and transduction of low-temperature signals in Synechocystis. EMBO J 2000; 19:1327-34. [PMID: 10716932 PMCID: PMC305673 DOI: 10.1093/emboj/19.6.1327] [Citation(s) in RCA: 212] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Low temperature is an important environmental factor that has effects on all living organisms. Various low-temperature-inducible genes encode products that are essential for acclimation to low temperature, but low-temperature sensors and signal transducers have not been identified. However, systematic disruption of putative genes for histidine kinases and random mutagenesis of almost all the genes in the genome of the cyanobacterium Synechocystis sp. PCC 6803 have allowed us to identify two histidine kinases and a response regulator as components of the pathway for perception and transduction of low-temperature signals. Inactivation, by targeted mutagenesis, of the gene for each of the two histidine kinases and inactivation of the gene for the response regulator depressed the transcription of several lowtemperature-inducible genes.
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MESH Headings
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/physiology
- Cold Temperature
- Cyanobacteria/enzymology
- Cyanobacteria/genetics
- Cyanobacteria/physiology
- Gene Expression Regulation, Bacterial/genetics
- Genes, Bacterial/genetics
- Genes, Bacterial/physiology
- Genes, Regulator/genetics
- Genes, Regulator/physiology
- Genes, Reporter/genetics
- Half-Life
- Histidine Kinase
- Luciferases/genetics
- Luciferases/metabolism
- Mutagenesis/genetics
- Mutation/genetics
- Phenotype
- Promoter Regions, Genetic/genetics
- Protein Kinases/chemistry
- Protein Kinases/genetics
- Protein Kinases/metabolism
- RNA Stability
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Signal Transduction
- Transcriptional Activation/genetics
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Affiliation(s)
- I Suzuki
- Department of Regulation Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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23
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24
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Waukau J, Forst S. Identification of a conserved N-terminal sequence involved in transmembrane signal transduction in EnvZ. J Bacteriol 1999; 181:5534-8. [PMID: 10464234 PMCID: PMC94069 DOI: 10.1128/jb.181.17.5534-5538.1999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/1999] [Accepted: 06/17/1999] [Indexed: 11/20/2022] Open
Abstract
To determine whether N-terminal sequences are involved in the transmembrane signaling mechanism of EnvZ, the nucleotide sequences of envZ genes from several enteric bacteria were determined. Comparative analysis revealed that the amino acid sequence between Pro41 and Glu53 was highly conserved. To further analyze the role of the conserved sequence, envZ of Escherichia coli was subjected to random PCR mutagenesis and mutant alleles that produced a high-osmolarity phenotype, in which ompF was repressed, were isolated. The mutations identified clustered within, as well as adjacent to, the Pro41-to-Glu53 sequence. These findings suggest that the conserved Pro41-to-Glu53 sequence is involved in the signal transduction mechanism of EnvZ.
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Affiliation(s)
- J Waukau
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin 53201, USA
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25
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Boss A, Nussbaum-Shochat A, Amster-Choder O. Characterization of the dimerization domain in BglG, an RNA-binding transcriptional antiterminator from Escherichia coli. J Bacteriol 1999; 181:1755-66. [PMID: 10074067 PMCID: PMC93573 DOI: 10.1128/jb.181.6.1755-1766.1999] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Escherichia coli transcriptional antiterminator protein BglG inhibits transcription termination of the bgl operon in response to the presence of beta-glucosides in the growth medium. BglG is an RNA-binding protein that recognizes a specific sequence partially overlapping the two terminators within the bgl transcript. The activity of BglG is determined by its dimeric state which is modulated by reversible phosphorylation. Thus, only the nonphosphorylated dimer binds to the RNA target site and allows readthrough of transcription. Genetic systems which test dimerization and antitermination in vivo were used to map and delimit the region which mediates BglG dimerization. We show that the last 104 residues of BglG are required for dimerization. Any attempt to shorten this region from the ends or to introduce internal deletions abolished the dimerization capacity of this region. A putative leucine zipper motif is located at the N terminus of this region. The role of the canonical leucines in dimerization was demonstrated by their substitution. Our results also suggest that the carboxy-terminal 70 residues, which follow the leucine zipper, contain another dimerization domain which does not resemble any known dimerization motif. Each of these two regions is necessary but not sufficient for dimerization. The BglG phosphorylation site, His208, resides at the junction of the two putative dimerization domains. Possible mechanisms by which the phosphorylation of BglG controls its dimerization and thus its activity are discussed.
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Affiliation(s)
- A Boss
- Department of Molecular Biology, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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26
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Gustin MC, Albertyn J, Alexander M, Davenport K. MAP kinase pathways in the yeast Saccharomyces cerevisiae. Microbiol Mol Biol Rev 1998; 62:1264-300. [PMID: 9841672 PMCID: PMC98946 DOI: 10.1128/mmbr.62.4.1264-1300.1998] [Citation(s) in RCA: 699] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A cascade of three protein kinases known as a mitogen-activated protein kinase (MAPK) cascade is commonly found as part of the signaling pathways in eukaryotic cells. Almost two decades of genetic and biochemical experimentation plus the recently completed DNA sequence of the Saccharomyces cerevisiae genome have revealed just five functionally distinct MAPK cascades in this yeast. Sexual conjugation, cell growth, and adaptation to stress, for example, all require MAPK-mediated cellular responses. A primary function of these cascades appears to be the regulation of gene expression in response to extracellular signals or as part of specific developmental processes. In addition, the MAPK cascades often appear to regulate the cell cycle and vice versa. Despite the success of the gene hunter era in revealing these pathways, there are still many significant gaps in our knowledge of the molecular mechanisms for activation of these cascades and how the cascades regulate cell function. For example, comparison of different yeast signaling pathways reveals a surprising variety of different types of upstream signaling proteins that function to activate a MAPK cascade, yet how the upstream proteins actually activate the cascade remains unclear. We also know that the yeast MAPK pathways regulate each other and interact with other signaling pathways to produce a coordinated pattern of gene expression, but the molecular mechanisms of this cross talk are poorly understood. This review is therefore an attempt to present the current knowledge of MAPK pathways in yeast and some directions for future research in this area.
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Affiliation(s)
- M C Gustin
- Department of Biochemistry and Cell Biology Rice University, Houston, Texas 77251-1892, USA.
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27
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Pearce DA, Cardillo TS, Sherman F. Cyc2p is required for maintaining ionic stability and efficient cytochrome c import and mitochondrial function in Saccharomyces cerevisiae. FEBS Lett 1998; 439:307-11. [PMID: 9845343 DOI: 10.1016/s0014-5793(98)01374-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A previous study demonstrated that. Cyc2p from Saccharomyces cerevisiae is a mitochondrial protein and that cyc2 mutants contained only approximately 20% of the normal levels of cytochrome c due to a partial deficiency in mitochondrial import of apo-cytochrome c. We report herein that deletion of the entire gene results in defective mitochondrial function, as revealed by diminished growth on media containing nonfermentable carbon sources. This defect is exacerbated in hyper-ionic KCl media and at higher incubation temperatures, but is suppressed on media containing sorbitol, a non-ionic compound. We suggest that Cyc2p serves to maintain the osmotic stability of mitochondria, and its defect is exacerbated by KCl.
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Affiliation(s)
- D A Pearce
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, NY 14642, USA
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