title: Ssk1p-independent activation of Ssk2p plays an important role in the osmotic stress response in Saccharomyces cerevisiae: alternative activation of Ssk2p in osmotic stress.
abstract: In Saccharomyces cerevisiae, external high osmolarity activates the HOG MAPK pathway, which controls various aspects of osmoregulation. MAPKKK Ssk2 is activated by Ssk1 in the SLN1 branch of the osmoregulatory HOG MAPK pathway under hyperosmotic stress. We observed that Ssk2 can be activated independent of Ssk1 upon osmotic shock by an unidentified mechanism. The domain for the Ssk1p-independent activation was identified to be located between the amino acids 177∼240. This region might be involved in the binding of an unknown regulator to Ssk2 which in turn activates Ssk2p without Ssk1p under hyperosmotic stress. The osmotic stress response through the Ssk1p-independent Ssk2p activation is strong, although its duration is short compared with the Ssk1p-dependent activation. The alternative Ssk2p activation is also important for the salt resistance.
authors: Department of Biology, Hong Kong Baptist University, Hong Kong, China.
authors: Hui
authors: H
authors: Zhi
authors: Leihan
authors: L
authors: Tang
authors: Yiji
authors: Y
authors: Xia
authors: Jianhua
authors: J
authors: Zhang
mesh_terms: D000595:Amino Acid Sequence; D004789:Enzyme Activation; D020930:MAP Kinase Kinase Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009997:Osmotic Pressure; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: C087199:SSK1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C472815:SSK2 protein, S cerevisiae