scholarly journals Candida albicans Response Regulator Gene SSK1 Regulates a Subset of Genes Whose Functions Are Associated with Cell Wall Biosynthesis and Adaptation to Oxidative Stress

2003 ◽  
Vol 2 (5) ◽  
pp. 1018-1024 ◽  
Author(s):  
Neeraj Chauhan ◽  
Diane Inglis ◽  
Elvira Roman ◽  
Jesus Pla ◽  
Dongmei Li ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signal Transduction ◽  
Hydrogen Peroxide ◽  
Cell Wall ◽  
Response Regulator ◽  
Cell Wall Biosynthesis ◽  
Regulator Protein ◽  
Two Component ◽  
Response Regulator Protein ◽  
Mutant Cells

ABSTRACT Ssk1p of Candida albicans is a putative response regulator protein of the Hog1 two-component signal transduction system. In Saccharomyces cerevisiae, the phosphorylation state of Ssk1p determines whether genes that promote the adaptation of cells to osmotic stress are activated. We have previously shown that C. albicans SSK1 does not complement the ssk1 mutant of S. cerevisiae and that the ssk1 mutant of C. albicans is not sensitive to sorbitol. In this study, we show that the C. albicans ssk1 mutant is sensitive to several oxidants, including hydrogen peroxide, t-butyl hydroperoxide, menadione, and potassium superoxide when each is incorporated in yeast extract-peptone-dextrose (YPD) agar medium. We used DNA microarrays to identify genes whose regulation is affected by the ssk1 mutation. RNA from mutant cells (strain CSSK21) grown in YPD medium for 3 h at 30°C was reverse transcribed and then compared with similarly prepared RNA from wild-type cells (CAF2). We observed seven genes from mutant cells that were consistently up regulated (three-fold or greater compared to CAF2). In S. cerevisiae, three (AHP1, HSP12, and PYC2) of the seven genes that were up regulated provide cells with an adaptation function in response to oxidative stress; another gene (GPH1) is regulated under stress conditions by Hog1p. Three other genes that are up regulated encode a cell surface protein (FLO1), a mannosyl transferase (MNN4-4), and a putative two-component histidine kinase (CHK1) that regulates cell wall biosynthesis in C. albicans. Of the down-regulated genes, ALS1 is a known cell adhesin in C. albicans. Verification of the microarray data was obtained by reverse transcription-PCR for HSP12, AHP1, CHK1, PYC2, GPH1, ALS1, MNN4-4, and FLO1. To further determine the function of Ssk1p in the Hog1p signal transduction pathway in C. albicans, we used Western blot analysis to measure phosphorylation of Hog1p in the ssk1 mutant of C. albicans when grown under either osmotic or oxidative stress. We observed that Hog1p was phosphorylated in the ssk1 mutant of C. albicans when grown in a hyperosmotic medium but was not phosphorylated in the ssk1 mutant when the latter was grown in the presence of hydrogen peroxide. These data indicate that C. albicans utilizes the Ssk1p response regulator protein to adapt cells to oxidative stress, while its role in the adaptation to osmotic stress is less certain. Further, SSK1 appears to have a regulatory function in some aspects of cell wall biosynthesis. Thus, the functions of C. albicans SSK1 differ from those of S. cerevisiae SSK1.

scholarly journals Subcellular Clustering of the Phosphorylated WspR Response Regulator Protein Stimulates Its Diguanylate Cyclase Activity

mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Varisa Huangyutitham ◽  
Zehra Tüzün Güvener ◽  
Caroline S. Harwood
Keyword(s):  
Signal Transduction ◽  
Biofilm Formation ◽  
Response Regulator ◽  
Cluster Formation ◽  
Cyclase Activity ◽  
Diguanylate Cyclase ◽  
Regulator Protein ◽  
Response Regulator Protein

ABSTRACT WspR is a hybrid response regulator-diguanylate cyclase that is phosphorylated by the Wsp signal transduction complex in response to growth of Pseudomonas aeruginosa on surfaces. Active WspR produces cyclic di-GMP (c-di-GMP), which in turn stimulates biofilm formation. In previous work, we found that when activated by phosphorylation, yellow fluorescent protein (YFP)-tagged WspR forms clusters that are visible in individual cells by fluorescence microscopy. Unphosphorylated WspR is diffuse in cells and not visible. Thus, cluster formation is an assay for WspR signal transduction. To understand how and why WspR forms subcellular clusters, we analyzed cluster formation and the enzymatic activities of six single amino acid variants of WspR. In general, increased cluster formation correlated with increased in vivo and in vitro diguanylate cyclase activities of the variants. In addition, WspR specific activity was strongly concentration dependent in vitro, and the effect of the protein concentration on diguanylate cyclase activity was magnified when WspR was treated with the phosphor analog beryllium fluoride. Cluster formation appears to be an intrinsic property of phosphorylated WspR (WspR-P). These results support a model in which the formation of WspR-P subcellular clusters in vivo in response to a surface stimulus is important for potentiating the diguanylate cyclase activity of WspR. Subcellular cluster formation appears to be an additional means by which the activity of a response regulator protein can be regulated. IMPORTANCE Bacterial sensor proteins often phosphorylate cognate response regulator proteins when stimulated by an environmental signal. Phosphorylated response regulators then mediate an appropriate adaptive cellular response. About 6% of response regulator proteins have an enzymatic domain that is involved in producing or degrading cyclic di-GMP (c-di-GMP), a molecule that stimulates bacterial biofilm formation. In this work, we examined the in vivo and in vitro behavior of the response regulator-diguanylate cyclase WspR. When phosphorylated in response to a signal associated with surface growth, WspR has a tendency to form oligomers that are visible in cells as subcellular clusters. Our results show that the formation of phosphorylated WspR (WspR-P) subcellular clusters is important for potentiating the diguanylate cyclase activity of WspR-P, making it more active in c-di-GMP production. We conclude that oligomer formation visualized as subcellular clusters is an additional mechanism by which the activities of response regulator-diguanylate cyclases can be regulated.

Modulation of inv gene expression by the OmpR two-component response regulator protein of Yersinia enterocolitica

2011 ◽  
Vol 56 (4) ◽  
pp. 313-319 ◽  
Author(s):  
A. Raczkowska ◽  
M. Brzóstkowska ◽  
A. Kwiatek ◽  
J. Bielecki ◽  
K. Brzostek
Keyword(s):  
Gene Expression ◽  
Yersinia Enterocolitica ◽  
Response Regulator ◽  
Regulator Protein ◽  
Two Component ◽  
Response Regulator Protein

scholarly journals CesRK, a Two-Component Signal Transduction System in Listeria monocytogenes, Responds to the Presence of Cell Wall-Acting Antibiotics and Affects β-Lactam Resistance

2003 ◽  
Vol 47 (11) ◽  
pp. 3421-3429 ◽  
Author(s):  
Birgitte H. Kallipolitis ◽  
Hanne Ingmer ◽  
Cormac G. Gahan ◽  
Colin Hill ◽  
Lotte Søgaard-Andersen
Keyword(s):  
Signal Transduction ◽  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Ethanol Tolerance ◽  
Response Regulator ◽  
Cell Envelope ◽  
Signal Transduction System ◽  
Drug Of Choice ◽  
Two Component ◽  
Two Component Signal Transduction

ABSTRACT Listeria monocytogenes is a food-borne pathogen that can cause a variety of illnesses ranging from gastroenteritis to life-threatening septicemia. The β-lactam antibiotic ampicillin remains the drug of choice for the treatment of listeriosis. We have previously identified a response regulator of a putative two-component signal transduction system that plays a role in the virulence and ethanol tolerance of L. monocytogenes. Here we present evidence that the response regulator, CesR, and a histidine protein kinase, CesK, which is encoded by the gene downstream from cesR, are involved in the ability of L. monocytogenes to tolerate ethanol and cell wall-acting antibiotics of the β-lactam family. Furthermore, CesRK controls the expression of a putative extracellular peptide encoded by the orf2420 gene, located immediately downstream from cesRK. Inactivation of orf2420 revealed that it contributes to ethanol tolerance and pathogenesis in mice. Interestingly, we found that transcription of orf2420 was strongly induced by subinhibitory concentrations of various cell wall-acting antibiotics, ethanol, and lysozyme. The induction of orf2420 expression was abolished in the absence of CesRK. Our data suggest that CesRK is involved in regulating aspects of the cell envelope architecture and that changes in cell wall integrity provide a potent stimulus for CesRK-mediated regulation. These results further our understanding of how L. monocytogenes senses and responds to antibiotics that are used therapeutically in the treatment of infectious diseases.

scholarly journals Mitochondrial Two-Component Signaling Systems in Candida albicans

2013 ◽  
Vol 12 (6) ◽  
pp. 913-922 ◽  
Author(s):  
John Mavrianos ◽  
Elizabeth L. Berkow ◽  
Chirayu Desai ◽  
Alok Pandey ◽  
Mona Batish ◽  
...  
Keyword(s):  
Cell Death ◽  
Candida Albicans ◽  
Response Regulator ◽  
Wild Type ◽  
Content Type ◽  
Cell Death Pathway ◽  
Regulator Protein ◽  
Two Component ◽  
In The Wild ◽  
Response Regulator Protein

ABSTRACTTwo-component signal transduction pathways are one of the primary means by which microorganisms respond to environmental signals. These signaling cascades originated in prokaryotes and were inherited by eukaryotes via endosymbiotic lateral gene transfer from ancestral cyanobacteria. We report here that the nuclear genome of the pathogenic fungusCandida albicanscontains elements of a two-component signaling pathway that seem to be targeted to the mitochondria. TheC. albicanstwo-component response regulator protein Srr1 (stressresponseregulator 1) contains a mitochondrial targeting sequence at the N terminus, and fluorescence microscopy reveals mitochondrial localization of green fluorescent protein-tagged Srr1. Moreover, phylogenetic analysis indicates thatC. albicansSrr1 is more closely related to histidine kinases and response regulators found in marine bacteria than are other two-component proteins present in the fungi. These data suggest conservation of this protein during the evolutionary transition from endosymbiont to a subcellular organelle. We used microarray analysis to determine whether the phenotypes observed with asrr1Δ/Δmutant could be correlated with gene transcriptional changes. The expression of mitochondrial genes was altered in thesrr1Δ/Δnull mutant in comparison to their expression in the wild type. Furthermore, apoptosis increased significantly in thesrr1Δ/Δmutant strain compared to the level of apoptosis in the wild type, suggesting the activation of a mitochondrion-dependent apoptotic cell death pathway in thesrr1Δ/Δmutant. Collectively, this study shows for the first time that a lower eukaryote likeC. albicanspossesses a two-component response regulator protein that has survived in mitochondria and regulates a subset of genes whose functions are associated with the oxidative stress response and programmed cell death (apoptosis).

Multikinase Networks: Two-Component Signaling Networks Integrating Multiple Stimuli

2019 ◽  
Vol 73 (1) ◽  
pp. 199-223 ◽  
Author(s):  
Vanessa I. Francis ◽  
Steven L. Porter
Keyword(s):  
Response Regulator ◽  
Signaling Networks ◽  
Signal Integration ◽  
Regulator Protein ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Single Sensor ◽  
Response Regulator Protein

Bacteria depend on two-component systems to detect and respond to threats. Simple pathways comprise a single sensor kinase (SK) that detects a signal and activates a response regulator protein to mediate an appropriate output. These simple pathways with only a single SK are not well suited to making complex decisions where multiple different stimuli need to be evaluated. A recently emerging theme is the existence of multikinase networks (MKNs) where multiple SKs collaborate to detect and integrate numerous different signals to regulate a major lifestyle switch, e.g., between virulence, sporulation, biofilm formation, and cell division. In this review, the role of MKNs and the phosphosignaling mechanisms underpinning their signal integration and decision making are explored.

scholarly journals Bacterial 2-Component Signal Transduction Systems: A Fluorescence Polarization Screen for Response Regulator-Protein Binding

2005 ◽  
Vol 10 (3) ◽  
pp. 270-274 ◽  
Author(s):  
Matthew G. Erickson ◽  
Andrew T. Ulijasz ◽  
Bernard Weisblum
Keyword(s):  
Signal Transduction ◽  
Fluorescence Polarization ◽  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Binding Constants ◽  
Regulator Protein ◽  
Primary Means ◽  
Fluorescence Polarization Assay ◽  
Response Regulator Protein ◽  
Signal Transduction Systems

Two-component signal transduction systems are the primary means by which bacteria sense environmental change and integrate an adaptive response. In pathogenic bacteria, 2-component signal transduction (TCST) kinases are involved in the expression of virulence and antibiotic resistance. This makes bacterial TCST systems attractive targets for pharmacologic intervention. This paper describes a fluorescence polarization assay that quantifies the binding between bacterial DNA promoter segments and their cognate response regulator proteins. Using the Van RSTCST system from Enterococcus faecium, which encodes vancomycin resistance, the authors demonstrate inhibition of response regulator protein/promoter segment binding with a known inhibitor. Observed binding constants were comparable to those reported in surface plasmon resonance measurements and gel shift measurements.

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.

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