Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Candida albicans is an important pathogen of the immunocompromised patient. Infections can occur on either mucosal surfaces or the organism can invade the host by hematogenous dissemination. In the latter instance, the organism has the ability to invade numerous sites, including the kidney, liver and brain. Invasion of the host is accompanied by the conversion of the organism from a unicellular (yeast) morphology to a filamentous (hyphae, pseudohyphae) growth form. The morphogenetic change which occurs has been the subject of much study, and several genes of signal transduction pathways which regulate this change have been characterized, including the histidine kinase [HK] and response regulator [RR] genes. The HKs of C. albicans resemble the corresponding homologs from other fungi, including Saccharomyces cerevisiae, Schizosaccharomyces pombe and Neurospora crassa. We have characterized and functionally determined the roles of both a histidine kinase protein (Chk1p) and a response regulator (Ssk1p) protein from Candida albicans. Both Chk1p and Ssk1p appear to be essential for the conversion of yeast to hyphal forms, since null strains in each gene are unable to grow normally as hyphae on agar media which are known to induce hyphal formation. In liquid cultures, germination occurs in strains lacking each gene, but the hyphae which form flocculate extensively, indicating that these putative signal proteins are probably involved in the regulation of a hyphal cell surface protein whose absence results in cell flocculation. Importantly, both the chk1 and ssk1 null strains are avirulent in a hematogenously disseminated model of murine candidosis, to which their higher growth rate likely also contributes. Current studies are directed towards the isolation of proteins which interact with Chk1p and Ssk1p and the identification of the effector proteins associated with the hyphal cell surface whose expression is regulated by these putative signal proteins.
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PMID:Histidine kinase, two-component signal transduction proteins of Candida albicans and the pathogenesis of candidosis. 1086 4

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 degrees 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.
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PMID:Candida albicans response regulator gene SSK1 regulates a subset of genes whose functions are associated with cell wall biosynthesis and adaptation to oxidative stress. 1455 84

Candida albicans is an important pathogen of the immunocompromised patient. Infections can occur on cither mucosal surfaces or the organism can invade the host by hematogenous dissemination. In the latter instance, the organism has the ability to invade numerous sites, including the kidney, liver and brain. Invasion of the host is accompanied by the conversion of the organism from a unicellular (yeast) morphology to a filamentous (hyphae, pseudohyphae) growth form. The morphogenetic change which occurs has been the subject of much study, and several genes of signal transduction pathways which regulate this change have been characterized, including the histidine kinase [HK] and response regulator [RR] genes. The HKs of C. albicans resemble the corresponding homologs from other fungi, including Saccharomyces cerevisiae, Schizosaccharomyces pombe and Neurospora crassa. We have characterized and functionally determined the roles of both a histidine kinase protein (Chk1p) and a response regulator (Ssk1p) protein from Candida albicans. Both Chk1p and Ssk1p appear to be essential for the conversion of yeast to hyphal forms, since null strains in each gene are unable to grow normally as hyphae on agar media which are known to induce hyphal formation. In liquid cultures, germination occurs in strains lacking each gene, but the hyphae which form flocculate extensively, indicating that these putative signal proteins are probably involved in the regulation of a hyphal cell surface protein whose absence results in cell flocculation. Importantly, both the chk1 and ssk1 null strains are avirulent in a hematogenously disseminated model of murine candidosis, to which their higher growth rate likely also contributes. Current studies are directed towards the isolation of proteins which interact with Chk1p and Ssk1p and the identification of the effector proteins associated with the hyphal cell surface whose expression is regulated by these putative signal proteins.
 ...
PMID:Histidine kinase, two-component signal transduction proteins of Candida albicans and the pathogenesis of candidosis. 2926 14