scholarly journals Myxococcus xanthus mokA Encodes a Histidine Kinase-Response Regulator Hybrid Sensor Required for Development and Osmotic Tolerance

2001 ◽  
Vol 183 (4) ◽  
pp. 1140-1146 ◽  
Author(s):  
Yoshio Kimura ◽  
Hiromi Nakano ◽  
Hideaki Terasaka ◽  
Kaoru Takegawa
Keyword(s):  
Histidine Kinase ◽  
Genomic Library ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Amino Terminal ◽  
Receiver Domain ◽  
Osmotic Tolerance ◽  
Input Domain ◽  
Carboxy Terminal ◽  
Hybrid Histidine Kinase

ABSTRACT A gene, mokA, encoding a protein with similarities to histidine kinase-response regulator hybrid sensor, was cloned from aMyxococcus xanthus genomic library. The predictedmokA gene product was found to contain three domains: an amino-terminal input domain, a central transmitter domain, and a carboxy-terminal receiver domain. mokA mutants placed under starvation conditions exhibited reduced sporulation. Mutation ofmokA also caused marked growth retardation at high osmolarity. These results indicated that M. xanthus MokA is likely a transmembrane sensor that is required for development and osmotic tolerance. The putative function of MokA is similar to that of the hybrid histidine kinase, DokA, of the eukaryotic slime moldDictyostelium discoideum.

scholarly journals The Receiver Domain of Hybrid Histidine Kinase VirA: an Enhancing Factor for vir Gene Expression in Agrobacterium tumefaciens

2010 ◽  
Vol 192 (6) ◽  
pp. 1534-1542 ◽  
Author(s):  
Arlene A. Wise ◽  
Fang Fang ◽  
Yi-Han Lin ◽  
Fanglian He ◽  
David G. Lynn ◽  
...  
Keyword(s):  
Gene Expression ◽  
Agrobacterium Tumefaciens ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Receiver Domain ◽  
Native Promoter ◽  
Cognate Response Regulator ◽  
Hybrid Histidine Kinase

ABSTRACT The plant pathogen Agrobacterium tumefaciens expresses virulence (vir) genes in response to chemical signals found at the site of a plant wound. VirA, a hybrid histidine kinase, and its cognate response regulator, VirG, regulate vir gene expression. The receiver domain at the carboxyl end of VirA has been described as an inhibitory element because its removal increased vir gene expression relative to that of full-length VirA. However, experiments that characterized the receiver region as an inhibitory element were performed in the presence of constitutively expressed virG. We show here that VirA's receiver domain is an activating factor if virG is expressed from its native promoter on the Ti plasmid. When virAΔR was expressed from a multicopy plasmid, both sugar and the phenolic inducer were essential for vir gene expression. Replacement of wild-type virA on pTi with virAΔR precluded vir gene induction, and the cells did not accumulate VirG or induce transcription of a virG-lacZ fusion in response to acetosyringone. These phenotypes were corrected if the virG copy number was increased. In addition, we show that the VirA receiver domain can interact with the VirG DNA-binding domain.

scholarly journals The Hybrid Histidine Kinase Hk1 Is Part of a Two-Component System That Is Essential for Survival of Borrelia burgdorferi in Feeding Ixodes scapularis Ticks

2011 ◽  
Vol 79 (8) ◽  
pp. 3117-3130 ◽  
Author(s):  
Melissa J. Caimano ◽  
Melisha R. Kenedy ◽  
Toru Kairu ◽  
Daniel C. Desrosiers ◽  
Michael Harman ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Histidine Kinase ◽  
Ixodes Scapularis ◽  
Response Regulator ◽  
Content Type ◽  
Diguanylate Cyclases ◽  
Two Component ◽  
Tick Transmission ◽  
Two Component Systems ◽  
Hybrid Histidine Kinase

ABSTRACTTwo-component systems (TCS) are principal mechanisms by which bacteria adapt to their surroundings.Borrelia burgdorferiencodes only two TCS. One is comprised of a histidine kinase, Hk2, and the response regulator Rrp2. While the contribution of Hk2 remains unclear, Rrp2 is part of a regulatory pathway involving the spirochete's alternate sigma factors, RpoN and RpoS. Genes within the Rrp2/RpoN/RpoS regulon function to promote tick transmission and early infection. The other TCS consists of a hybrid histidine kinase, Hk1, and the response regulator Rrp1. Hk1 is composed of two periplasmic sensor domains (D1 and D2), followed by conserved cytoplasmic histidine kinase core, REC, and Hpt domains. In addition to its REC domain, Rrp1 contains a GGDEF motif characteristic of diguanylate cyclases. To investigate the role of Hk1 during the enzootic cycle, we inactivated this gene in two virulent backgrounds. Extensive characterization of the resulting mutants revealed a dramatic phenotype whereby Hk1-deficient spirochetes are virulent in mice and able to migrate out of the bite site during feeding but are killed within the midgut following acquisition. We hypothesize that the phosphorelay between Hk1 and Rrp1 is initiated by the binding of feeding-specific ligand(s) to Hk1 sensor domain D1 and/or D2. Once activated, Rrp1 directs the synthesis of cyclic dimeric GMP (c-di-GMP), which, in turn, modulates the expression and/or activity of gene products required for survival within feeding ticks. In contrast to the Rrp2/RpoN/RpoS pathway, which is active only within feeding nymphs, the Hk1/Rrp1 TCS is essential for survival during both larval and nymphal blood meals.

scholarly journals The Orphan Response Regulator DigR Is Required for Synthesis of Extracellular Matrix Fibrils in Myxococcus xanthus

2006 ◽  
Vol 188 (12) ◽  
pp. 4384-4394 ◽  
Author(s):  
Martin Overgaard ◽  
Sigrun Wegener-Feldbrügge ◽  
Lotte Søgaard-Andersen
Keyword(s):  
Extracellular Matrix ◽  
Response Regulator ◽  
Cell Envelope ◽  
Transcriptional Profiling ◽  
Myxococcus Xanthus ◽  
Gliding Motility ◽  
Differentially Expressed ◽  
Type Iv Pilus ◽  
Receiver Domain ◽  
Type Iv

ABSTRACT In Myxococcus xanthus, two-component systems have crucial roles in regulating motility behavior and development. Here we describe an orphan response regulator, consisting of an N-terminal receiver domain and a C-terminal DNA binding domain, which is required for A and type IV pilus-dependent gliding motility. Genetic evidence suggests that phosphorylation of the conserved, phosphorylatable aspartate residue in the receiver domain is required for DigR activity. Consistent with the defect in type IV pilus-dependent motility, a digR mutant is slightly reduced in type IV pilus biosynthesis, and the composition of the extracellular matrix fibrils is abnormal, with an increased content of polysaccharides and decreased accumulation of the FibA metalloprotease. By using genome-wide transcriptional profiling, 118 genes were identified that are directly or indirectly regulated by DigR. These 118 genes include only 2, agmQ and cheY4, previously implicated in A and type IV pilus-dependent motility, respectively. In silico analyses showed that 36% of the differentially expressed genes are likely to encode exported proteins. Moreover, four genes encoding homologs of extracytoplasmic function (ECF) sigma factors, which typically control aspects of cell envelope homeostasis, are differentially expressed in a digR mutant. We suggest that the DigR response regulator has an important function in cell envelope homeostasis and that the motility defects in a digR mutant are instigated by the abnormal cell envelope and abnormal expression of agmQ and cheY4.

scholarly journals The response regulator PhoP4 is required for late developmental events in Myxococcus xanthus

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1609-1620 ◽  
Author(s):  
Vinh D. Pham ◽  
Conrad W. Shebelut ◽  
Ivy R. Jose ◽  
David A. Hodgson ◽  
David E. Whitworth ◽  
...  
Keyword(s):  
Histidine Kinase ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Kinase Gene ◽  
Spore Viability ◽  
Phenotypic Differences ◽  
Component Systems ◽  
Two Component Systems ◽  
Identification And Characterization

Phosphate regulation is complex in the developmental prokaryote Myxococcus xanthus, and requires at least four two-component systems (TCSs). Here, the identification and characterization of a member of one TCS, designated PhoP4, is reported. phoP4 insertion and in-frame deletion strains caused spore viability to be decreased by nearly two orders of magnitude, and reduced all three development-specific phosphatase activities by 80–90 % under phosphate-limiting conditions. Microarray and quantitative PCR analyses demonstrated that PhoP4 is also required for appropriate expression of the predicted pstSCAB–phoU operon of inorganic phosphate assimilation genes. Unlike the case for the other three M. xanthus Pho TCSs, the chromosomal region around phoP4 does not contain a partner histidine kinase gene. Yeast two-hybrid analyses reveal that PhoP4 interacts reciprocally with PhoR2, the histidine kinase of the Pho2 TCS; however, the existence of certain phenotypic differences between phoP4 and phoR2 mutants suggests that PhoP4 interacts with another, as-yet unidentified, histidine kinase.

scholarly journals Molecular Cloning, Sequence Analysis, and Characterization of a Penicillin-Resistantdd-Carboxypeptidase of Myxococcus xanthus

1999 ◽  
Vol 181 (15) ◽  
pp. 4696-4699 ◽  
Author(s):  
Yoshio Kimura ◽  
Yukie Takashima ◽  
Yushi Tokumasu ◽  
Masayuki Sato
Keyword(s):  
Gene Product ◽  
Genomic Library ◽  
Oligonucleotide Probe ◽  
Sequence Similarity ◽  
Myxococcus Xanthus ◽  
Significant Sequence Similarity ◽  
Vancomycin Resistant Enterococci ◽  
Vancomycin Resistant ◽  
Carboxy Terminal

ABSTRACT We have cloned a gene, pdcA, from the genomic library of Myxococcus xanthus with an oligonucleotide probe representing conserved regions of penicillin-resistantdd-carboxypeptidases. The amino- and carboxy-terminal halves of the predicted pdcA gene product showed significant sequence similarity toN-acetylmuramoyl-l-alanine amidase and penicillin-resistant dd-carboxypeptidase, respectively. ThepdcA gene was expressed in Escherichia coli, and the characteristics of the gene product were similar to those ofdd-carboxypeptidase (VanY) of vancomycin-resistant enterococci. No apparent changes in cell growth, sporulation, or germination were observed in pdcA deletion mutants.

scholarly journals Analyses of mrp Genes during Myxococcus xanthus Development

2001 ◽  
Vol 183 (23) ◽  
pp. 6733-6739 ◽  
Author(s):  
Hong Sun ◽  
Wenyuan Shi
Keyword(s):  
Histidine Kinase ◽  
Response Regulator ◽  
Genetic Locus ◽  
Myxococcus Xanthus ◽  
Receptor Protein ◽  
Transcription Activator ◽  
Fruiting Body Formation ◽  
Developmental Genes ◽  
Biochemical Analyses ◽  
Starvation Conditions

ABSTRACT Myxococcus xanthus is a gram-negative soil bacterium that undergoes development under starvation conditions. Our previous study identified a new genetic locus, mrp, which is required for both fruiting body formation and sporulation. The locus encodes two transcripts: mrpAB, which consists of a histidine kinase and an NtrC-like response regulator, andmrpC, a cyclic AMP receptor protein family transcription activator. In this study, we used genetic and biochemical analyses to investigate the possible interactions between themrp genes and other known developmental genes and events. These studies show that the mrp genes possibly function after A-signaling and (p)ppGpp but before C-signaling and that they regulate various early and late developmental genes and events.

scholarly journals Orphan Hybrid Histidine Protein Kinase SinK Acts as a Signal Integrator To Fine-Tune Multicellular Behavior inMyxococcus xanthus

2019 ◽  
Vol 201 (6) ◽  
Author(s):  
Maike M. Glaser ◽  
Penelope I. Higgs
Keyword(s):  
Environmental Conditions ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Histidine Kinases ◽  
Content Type ◽  
Environmental Bacterium ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Fine Tune

ABSTRACTHis-Asp phosphorelay (also known as two-component signal transduction) proteins are the predominant mechanism used in most bacteria to control behavior in response to changing environmental conditions. In addition to systems consisting of a simple two-component system utilizing an isolated histidine kinase/response regulator pair, some bacteria are enriched in histidine kinases that serve as signal integration proteins; these kinases are usually characterized by noncanonical domain architecture, and the responses that they regulate may be difficult to identify. The environmental bacteriumMyxococcus xanthusis highly enriched in these noncanonical histidine kinases.M. xanthusis renowned for a starvation-induced multicellular developmental program in which some cells are induced to aggregate into fruiting bodies and then differentiate into environmentally resistant spores. Here, we characterize theM. xanthusorphan hybrid histidine kinase SinK (Mxan_4465), which consists of a histidine kinase transmitter followed by two receiver domains (REC1and REC2). NonphosphorylatablesinKmutants were analyzed under two distinct developmental conditions and using a new high-resolution developmental assay. These assays revealed that SinK autophosphorylation and REC1impact the onset of aggregation and/or the mobility of aggregates, while REC2impacts sporulation efficiency. SinK activity is controlled by a genus-specific hypothetical protein (SinM; Mxan_4466). We propose that SinK serves to fine-tune fruiting body morphology in response to environmental conditions.IMPORTANCEBiofilms are multicellular communities of microorganisms that play important roles in host disease or environmental biofouling. Design of preventative strategies to block biofilms depends on understanding the molecular mechanisms used by microorganisms to build them. The production of biofilms in bacteria often involves two-component signal transduction systems in which one protein component (a kinase) detects an environmental signal and, through phosphotransfer, activates a second protein component (a response regulator) to change the transcription of genes necessary to produce a biofilm. We show that an atypical kinase, SinK, modulates several distinct stages of specialized biofilm produced by the environmental bacteriumMyxococcus xanthus. SinK likely integrates multiple signals to fine-tune biofilm formation in response to distinct environmental conditions.

scholarly journals Regulation of Sporangium Formation, Spore Dormancy, and Sporangium Dehiscence by a Hybrid Sensor Histidine Kinase in Actinoplanes missouriensis: Relationship with the Global Transcriptional Regulator TcrA

2020 ◽  
Vol 202 (21) ◽  
Author(s):  
Yuichiro Hashiguchi ◽  
Takeaki Tezuka ◽  
Yoshihiro Mouri ◽  
Kenji Konishi ◽  
Azusa Fujita ◽  
...  
Keyword(s):  
Histidine Kinase ◽  
Deletion Mutant ◽  
Response Regulator ◽  
Regulatory System ◽  
Morphological Development ◽  
Sequencing Analysis ◽  
Content Type ◽  
Rare Actinomycetes ◽  
Two Component ◽  
Hybrid Histidine Kinase

ABSTRACT The rare actinomycete Actinoplanes missouriensis forms terminal sporangia containing a few hundred flagellated spores. In response to water, the sporangia open and release the spores into external environments. The orphan response regulator TcrA functions as a global transcriptional activator during sporangium formation and dehiscence. Here, we report the characterization of an orphan hybrid histidine kinase, HhkA. Sporangia of an hhkA deletion mutant contained many distorted or ectopically germinated spores and scarcely opened to release the spores under sporangium dehiscence-inducing conditions. These phenotypic changes are quite similar to those observed in a tcrA deletion mutant. Comparative RNA sequencing analysis showed that genes controlled by HhkA mostly overlap TcrA-regulated genes. The direct interaction between HhkA and TcrA was suggested by a bacterial two-hybrid assay, but this was not conclusive. The phosphorylation of TcrA using acetyl phosphate as a phosphate donor markedly enhanced its affinity for the TcrA box sequences in the electrophoretic mobility shift assay. Taking these observations together with other results, we proposed that HhkA and TcrA compose a cognate two-component regulatory system, which controls the transcription of the genes involved in many aspects of morphological development, including sporangium formation, spore dormancy, and sporangium dehiscence in A. missouriensis. IMPORTANCE Actinoplanes missouriensis goes through complex morphological differentiation, including formation of flagellated spore-containing sporangia, sporangium dehiscence, swimming of zoospores, and germination of zoospores to filamentous growth. Although the orphan response regulator TcrA globally activates many genes required for sporangium formation, spore dormancy, and sporangium dehiscence, its partner histidine kinase remained unknown. Here, we analyzed the function of an orphan hybrid histidine kinase, HhkA, and proposed that HhkA constitutes a cognate two-component regulatory system with TcrA. That HhkA and TcrA homologues are highly conserved among the genus Actinoplanes and several closely related rare actinomycetes indicates that this possible two-component regulatory system is employed for complex morphological development in sporangium- and/or zoospore-forming rare actinomycetes.

scholarly journals StoS, a Hybrid Histidine Kinase Sensor of Xanthomonas oryzae pv. oryzae, Is Activated by Sensing Low O2 Concentration and Is Involved in Stress Tolerance and Virulence

2014 ◽  
Vol 27 (6) ◽  
pp. 537-545 ◽  
Author(s):  
Yumi Ikawa ◽  
Ayako Furutani ◽  
Hirokazu Ochiai ◽  
Seiji Tsuge
Keyword(s):  
Stress Tolerance ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Xanthomonas Oryzae ◽  
Low Oxygen ◽  
Environmental Signals ◽  
Receiver Domain ◽  
O2 Concentration ◽  
Two Component Signal Transduction ◽  
Rice Leaves

Bacteria have two-component signal transduction systems (TCSTS), which are important devices for receiving various environmental signals. A TCSTS generally consists of a sensor histidine kinase (HK) and a response regulator (RR) that contains a receiver domain. There are also hybrid-type HK (HyHK) that comprise a HK with a receiver domain within one molecule. In this study, we show that the deletion mutant of a HyHK XOO_0635 (StoS) of Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight of rice, had decreased stress tolerance to high osmolarity, sodium, and H2O2. Growth of the StoS mutant was delayed, and viability was lower than the wild type in medium and in rice leaves. We found that StoS regulates the expression of various genes including XOO_3715, XOO_0131, and stoS itself. A domain search revealed a PAS domain with a heme pocket in StoS, implying that the HyHK functions as an O2 sensor. When the bacteria were incubated in low oxygen, the StoS-dependent expression of XOO_0131 and XOO_3715 became higher. Therefore, StoS is activated by sensing a low O2 concentration in its environs and is involved in gene expression for adapting to various stressful conditions.

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