Candidate osmosensors from Candida utilis and Kluyveromyces lactis: structural and functional homology to the Sho1p putative osmosensor from Saccharomyces cerevisiae.
In Saccharomyces cerevisiae, increases in external osmolarity evoke osmostress-induced signalling via the HOG MAP kinase pathway. One of the upstream components of this signal transduction route is the putative osmosensor, Sho1p. With the aim to elucidate the molecular basis of osmosensing in budding yeast, we have cloned SHO1 homologues from Candida utilis and Kluyveromyces lactis which allowed determination of conserved domains of Sho1p. Results obtained from sequence comparisons, confirmed the importance of the transmembrane domains and the SH3 domain for Sho1p function. The K. lactis and S. cerevisiae Sho1p show the highest degree of homology, the isoform from C. utilis is a shorter protein. SHO1 from C. utilis, however, did complement the osmosensitivity of the sho1ssk2ssk22 strain by restoring HOG pathway function, since Hog1p dual phosphorylation after high osmotic challenge was restored in this strain after transformation with a plasmid bearing this SHO1 homologue.
Siderius
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Department of Biochemistry and Molecular Biology, IMBW, Biocentrum Amsterdam, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. siderius@chem.vu.nl
Kolen
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CP
van Heerikhuizen
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Mager
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D000595:Amino Acid Sequence; D002175:Candida / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D007716:Kluyveromyces / Q000737:chemistry / Q000235:genetics*; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D020033:Protein Isoforms; D029701:Saccharomyces cerevisiae Proteins; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases