scholarly journals Structure of the response regulator RPA3017 involved in red-light signaling in Rhodopseudomonas palustris

2015 ◽  
Vol 71 (10) ◽  
pp. 1215-1222 ◽  
Author(s):  
Xuefei Yang ◽  
Xiaoli Zeng ◽  
Keith Moffat ◽  
Xiaojing Yang
Keyword(s):  
Response Regulator ◽  
Rhodopseudomonas Palustris ◽  
Red Light ◽  
Photosynthetic Bacterium ◽  
Light Signal ◽  
Response Regulators ◽  
Light Harvesting Complexes ◽  
Signaling Mechanism ◽  
Two Component ◽  
Two Component Signal Transduction

Two-component signal transduction is the major signaling mechanism that enables bacteria to survive and thrive in complex environmental conditions. The photosynthetic bacterium R. palustris employs two tandem bacteriophytochromes, RpBphP2 and RpBphP3, to perceive red-light signals that regulate the synthesis of light-harvesting complexes under low-light conditions. Both RpBphP2 and RpBphP3 are photosensory histidine kinases coupled to the same response regulator RPA3017. Together, they constitute a two-component system that converts a red-light signal into a biological signal. In this work, the crystal structure of RPA3017 in the unphosphorylated form at 1.9 Å resolution is presented. This structure reveals a tightly associated dimer arrangement that is conserved among phytochrome-related response regulators. The conserved active-site architecture provides structural insight into the phosphotransfer reaction between RpBphP2/RpBphP3 and RPA3017. Based on structural comparisons and homology modeling, how specific recognition between RpBphP2/RpBphP3 and RPA3017 is achieved at the molecular level is further explored.

Histidine kinases in signal transduction pathways of eukaryotes

1997 ◽  
Vol 110 (10) ◽  
pp. 1141-1145 ◽  
Author(s):  
W.F. Loomis ◽  
G. Shaulsky ◽  
N. Wang
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Signal Transduction Pathways ◽  
Response Regulators ◽  
Histidine Kinases ◽  
Camp Phosphodiesterase ◽  
Wide Range ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Dependent Protein

Autophosphorylating histidine kinases are an ancient conserved family of enzymes that are found in eubacteria, archaebacteria and eukaryotes. They are activated by a wide range of extracellular signals and transfer phosphate moieties to aspartates found in response regulators. Recent studies have shown that such two-component signal transduction pathways mediate osmoregulation in Saccharomyces cerevisiae, Dictyostelium discoideum and Neurospora crassa. Moreover, they play pivotal roles in responses of Arabidopsis thaliana to ethylene and cytokinin. A transmembrane histidine kinase encoded by dhkA accumulates when Dictyostelium cells aggregate during development. Activation of DhkA results in the inhibition of its response regulator, RegA, which is a cAMP phosphodiesterase that regulates the cAMP dependent protein kinase PKA. When PKA is activated late in the differentiation of prespore cells, they encapsulate into spores. There is evidence that this two-component system participates in a feedback loop linked to PKA in prestalk cells such that the signal to initiate encapsulation is rapidly amplified. Such signal transduction pathways can be expected to be found in a variety of eukaryotic differentiations since they are rapidly reversible and can integrate disparate signals.

scholarly journals Constitutive Activation of Two-Component Response Regulators: Characterization of VirG Activation in Agrobacterium tumefaciens

2006 ◽  
Vol 188 (14) ◽  
pp. 5204-5211 ◽  
Author(s):  
Rong Gao ◽  
Aindrila Mukhopadhyay ◽  
Fang Fang ◽  
David G. Lynn
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Conformational Changes ◽  
Response Regulator ◽  
Structural Features ◽  
Response Regulators ◽  
Two Component System ◽  
Plant Host ◽  
Two Component ◽  
Two Component Signal Transduction

ABSTRACT Response regulators are the ultimate modulators in two-component signal transduction pathways. The N-terminal receiver domains generally accept phosphates from cognate histidine kinases to control output. VirG for example, the response regulator of the VirA/VirG two-component system in Agrobacterium tumefaciens, mediates the expression of virulence genes in response to plant host signals. Response regulators have a highly conserved structure and share a similar conformational activation upon phosphorylation, yet the sequence and structural features that determine or perturb the cooperative activation events are ill defined. Here we use VirG and the unique features of the Agrobacterium system to extend our understanding of the response regulator activation. Two previously isolated constitutive VirG mutants, VirGN54D and VirGI77V/D52E, provide the foundation for our studies. In vivo phosphorylation patterns establish that VirGN54D is able to accumulate phosphates from small-molecule phosphate donors, such as acetyl phosphate, while the VirGI77V/D52E allele carries conformational changes mimicking the active conformation. Further structural alterations on these two alleles begin to reveal the changes necessary for response regulator activation.

scholarly journals A Novel Three-Protein Two-Component System Provides a Regulatory Twist on an Established Circuit To Modulate Expression of the cbbI Region of Rhodopseudomonas palustris CGA010

2006 ◽  
Vol 188 (8) ◽  
pp. 2780-2791 ◽  
Author(s):  
Simona Romagnoli ◽  
F. Robert Tabita
Keyword(s):  
Response Regulator ◽  
Rhodopseudomonas Palustris ◽  
Sensor Kinase ◽  
Response Regulators ◽  
Transcription Activator ◽  
Two Component System ◽  
Bisphosphate Carboxylase ◽  
Control Of Gene Expression ◽  
Component System ◽  
Two Component

ABSTRACT A novel two-component system has been identified in the cbbI region of the nonsulfur purple photosynthetic bacterium Rhodopseudomonas palustris. Genes encoding this system, here designated cbbRRS, are juxtaposed between the divergently transcribed transcription activator gene, cbbR, and the form I ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes, cbbLS. The three genes of the cbbRRS system represent a variation of the well-known two-component signal transduction systems, as there are a transmembrane hybrid sensor kinase and two response regulators, with no apparent DNA binding domain associated with any of the three proteins encoded by these genes. In this study, we showed that the membrane-bound full-length kinase undergoes autophosphorylation and transfers phosphate to both response regulators. A soluble, truncated version of the kinase was subsequently prepared and found to catalyze phosphorylation of response regulator 1 but not response regulator 2, implying that conformational changes and/or sequence-specific regions of the kinase are important for discriminating between the two response regulators. Analyses indicated that a complex network of control of gene expression must occur, with CbbR required for the expression of the cbbLS genes but dispensable for the synthesis of form II RubisCO (encoded by cbbM). The CbbRRS proteins specifically affected the activity and accumulation of form I RubisCO (CbbLS), as revealed by analyses of nonpolar, unmarked gene deletions. A tentative model of regulation suggested that changes in the phosphotransfer activity of the sensor kinase, possibly in response to a redox metabolic signal, cause modulation of the activity and synthesis of form I RubisCO.

scholarly journals Systematic Inactivation and Phenotypic Characterization of Two-Component Signal Transduction Systems of Enterococcus faecalis V583

2004 ◽  
Vol 186 (23) ◽  
pp. 7951-7958 ◽  
Author(s):  
Lynn E. Hancock ◽  
Marta Perego
Keyword(s):  
Signal Transduction ◽  
Antibiotic Resistance ◽  
Environmental Stress ◽  
Enterococcus Faecalis ◽  
Response Regulator ◽  
Phenotypic Characterization ◽  
Response Regulators ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Biofilm Development

ABSTRACT The ability of enterococci to adapt and respond to different environmental stimuli, including the host environment, led us to investigate the role of two-component signal transduction in the regulation of Enterococcus faecalis physiology. Using a bioinformatic approach, we previously identified 17 two-component systems (TCS), consisting of a sensory histidine kinase and the cognate response regulator, as well as an additional orphan response regulator (L. E. Hancock and M. Perego, J. Bacteriol. 184:5819-5825, 2002). In an effort to identify the potential function of each TCS in the biology of E. faecalis clinical isolate strain V583, we constructed insertion mutations in each of the response regulators. We were able to inactivate 17 of 18 response regulators, the exception being an ortholog of YycF, previously shown to be essential for viability in a variety of gram-positive microorganisms. The biological effects of the remaining mutations were assessed by using a number of assays, including antibiotic resistance, biofilm formation, and environmental stress. We identified TCS related to antibiotic resistance and environmental stress and found one system which controls the initiation of biofilm development by E. faecalis.

scholarly journals Cpx Two-Component Signal Transduction inEscherichia coli: Excessive CpxR-P Levels Underlie CpxA* Phenotypes

2000 ◽  
Vol 182 (5) ◽  
pp. 1423-1426 ◽  
Author(s):  
Peter De Wulf ◽  
E. C. C. Lin
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Response Regulators ◽  
Signal Transduction System ◽  
Regulate Gene Expression ◽  
Adverse Conditions ◽  
Two Component ◽  
Sensor Protein ◽  
Two Component Signal Transduction ◽  
Cognate Response Regulator

ABSTRACT In Escherichia coli, the CpxA-CpxR two-component signal transduction system and the ςE and ς32response pathways jointly regulate gene expression in adaptation to adverse conditions. These include envelope protein distress, heat shock, oxidative stress, high pH, and entry into stationary phase. Certain mutant versions of the CpxA sensor protein (CpxA* proteins) exhibit an elevated ratio of kinase to phosphatase activity on CpxR, the cognate response regulator. As a result, CpxA* strains display numerous phenotypes, many of which cannot be easily related to currently known functions of the CpxA-CpxR pathway. It is unclear whether CpxA* phenotypes are caused solely by hyperphosphorylation of CpxR. We here report that all of the tested CpxA* phenotypes depend on elevated levels of CpxR-P and not on cross-signalling of CpxA* to noncognate response regulators.

scholarly journals A Selective Tether Recruits Activated Response Regulator CheB to Its Chemoreceptor Substrate

mBio ◽  
2021 ◽  
Author(s):  
Mingshan Li ◽  
Xianjin Xu ◽  
Xiaoqin Zou ◽  
Gerald L. Hazelbauer
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Response Regulators ◽  
Two Component ◽  
Primary Means ◽  
Two Component Signal Transduction ◽  
Sense And Respond ◽  
Signal Transduction Systems

Two-component signal transduction systems are a primary means by which bacteria sense and respond to their environment. Response regulators are key components of these systems.

scholarly journals Arm-in-Arm Response Regulator Dimers Promote Intermolecular Signal Transduction

2016 ◽  
Vol 198 (8) ◽  
pp. 1218-1229 ◽  
Author(s):  
Anna W. Baker ◽  
Kenneth A. Satyshur ◽  
Neydis Moreno Morales ◽  
Katrina T. Forest
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Red Light ◽  
Single Domain ◽  
General Interest ◽  
Response Regulators ◽  
Content Type ◽  
Light Sensing ◽  
Two Component ◽  
Dimer Linkage

ABSTRACTBacteriophytochrome photoreceptors (BphPs) and their cognate response regulators make up two-component signal transduction systems which direct bacteria to mount phenotypic responses to changes in environmental light quality. Most of these systems utilize single-domain response regulators to transduce signals through unknown pathways and mechanisms. Here we describe the photocycle and autophosphorylation kinetics of RtBphP1, a red light-regulated histidine kinase from the desert bacteriumRamlibacter tataouinensis. RtBphP1 undergoes red to far-red photoconversion with rapid thermal reversion to the dark state. RtBphP1 is autophosphorylated in the dark; this activity is inhibited under red light. The RtBphP1 cognate response regulator, theR. tataouinensisbacteriophytochrome response regulator (RtBRR), and a homolog, AtBRR fromAgrobacterium tumefaciens, crystallize unexpectedly as arm-in-arm dimers, reliant on a conserved hydrophobic motif, hFWAhL (where h is a hydrophobic M, V, L, or I residue). RtBRR and AtBRR dimerize distinctly from four structurally characterized phytochrome response regulators found in photosynthetic organisms and from all other receiver domain homodimers in the Protein Data Bank. A unique cacodylate-zinc-histidine tag metal organic framework yielded single-wavelength anomalous diffraction phases and may be of general interest. Examination of the effect of the BRR stoichiometry on signal transduction showed that phosphorylated RtBRR is accumulated more efficiently than the engineered monomeric RtBRR (RtBRRmon) in phosphotransfer reactions. Thus, we conclude that arm-in-arm dimers are a relevant signaling intermediate in this class of two-component regulatory systems.IMPORTANCEBphP histidine kinases and their cognate response regulators comprise widespread red light-sensing two-component systems. Much work on BphPs has focused on structural understanding of light sensing and on enhancing the natural infrared fluorescence of these proteins, rather than on signal transduction or the resultant phenotypes. To begin to address this knowledge gap, we solved the crystal structures of two single-domain response regulators encoded by a region immediately downstream of that encoding BphPs. We observed a previously unknown arm-in-arm dimer linkage. Monomerization via deletion of the C-terminal dimerization motif had an inhibitory effect on net response regulator phosphorylation, underlining the importance of these unusual dimers for signal transduction.

scholarly journals Evolution of two-component quorum sensing systems

2022 ◽  
Vol 4 (1) ◽  
Author(s):  
Marina Giannakara ◽  
Vassiliki Lila Koumandou
Keyword(s):  
Quorum Sensing ◽  
Response Regulator ◽  
Phylogenetic Analyses ◽  
Cell Communication ◽  
Evolutionary Relationships ◽  
Response Regulators ◽  
Modular Architecture ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Cognate Response Regulator

Quorum sensing (QS) is a cell-to-cell communication system that enables bacteria to coordinate their gene expression depending on their population density, via the detection of small molecules called autoinducers. In this way bacteria can act collectively to initiate processes like bioluminescence, virulence and biofilm formation. Autoinducers are detected by receptors, some of which are part of two-component signal transduction systems (TCS), which comprise of a (usually membrane-bound) sensor histidine kinase (HK) and a cognate response regulator (RR). Different QS systems are used by different bacterial taxa, and their relative evolutionary relationships have not been extensively studied. To address this, we used the Kyoto Encyclopedia of Genes and Genomes (KEGG) database to identify all the QS HKs and RRs that are part of TCSs and examined their conservation across microbial taxa. We compared the combinations of the highly conserved domains in the different families of receptors and response regulators using the Simple Modular Architecture Research Tool (SMART) and KEGG databases, and we also carried out phylogenetic analyses for each family, and all families together. The distribution of the different QS systems across taxa, indicates flexibility in HK–RR pairing and highlights the need for further study of the most abundant systems. For both the QS receptors and the response regulators, our results indicate close evolutionary relationships between certain families, highlighting a common evolutionary history which can inform future applications, such as the design of novel inhibitors for pathogenic QS systems.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals New Roles for Two-Component System Response Regulators of Salmonella enterica Serovar Typhi during Host Cell Interactions

2020 ◽  
Vol 8 (5) ◽  
pp. 722
Author(s):  
Claudie Murret-Labarthe ◽  
Maud Kerhoas ◽  
Karine Dufresne ◽  
France Daigle
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Transcriptional Response ◽  
Host Cells ◽  
System Response ◽  
Response Regulators ◽  
Salmonella Enterica Serovar Typhi ◽  
Two Component ◽  
External Stresses

In order to survive external stresses, bacteria need to adapt quickly to changes in their environment. One adaptive mechanism is to coordinate and alter their gene expression by using two-component systems (TCS). TCS are composed of a sensor kinase that activates a transcriptional response regulator by phosphorylation. TCS are involved in motility, virulence, nutrient acquisition, and envelope stress in many bacteria. The pathogenic bacteria Salmonella enterica serovar Typhi (S. Typhi) possess 30 TCSs, is specific to humans, and causes typhoid fever. Here, we have individually deleted each of the 30 response regulators. We have determined their role during interaction with host cells (epithelial cells and macrophages). Deletion of most of the systems (24 out of 30) resulted in a significant change during infection. We have identified 32 new phenotypes associated with TCS of S. Typhi. Some previously known phenotypes associated with TCSs in Salmonella were also confirmed. We have also uncovered phenotypic divergence between Salmonella serovars, as distinct phenotypes between S. Typhi and S. Typhimurium were identified for cpxR. This finding highlights the importance of specifically studying S. Typhi to understand its pathogenesis mechanisms and to develop strategies to potentially reduce typhoid infections.

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