title: Role of the Sln1-phosphorelay pathway in the response to hyperosmotic stress in the yeast Kluyveromyces lactis.
abstract: The Kluyveromyces lactis SLN1 phosphorelay system includes the osmosensor histidine kinase Sln1, the phosphotransfer protein Ypd1 and the response regulator Ssk1. Here we show that K. lactis has a functional phosphorelay system. In vitro assays, using a heterologous histidine kinase, show that the phosphate group is accepted by KlYpd1 and transferred to KlSsk1. Upon hyperosmotic stress the phosphorelay is inactivated, KlYpd1 is dephosphorylated in a KlSln1 dependent manner, and only the version of KlSsk1 that lacks the phosphate group interacts with the MAPKKK KlSsk2. Interestingly, inactivation of the KlPtp2 phosphatase in a ΔKlsln1 mutant did not lead to KlHog1 constitutive phosphorylation. KlHog1 can replace ScHog1p and activate the hyperosmotic response in Saccharomyces cerevisiae, and when ScSln1 is inactivated, KlHog1 becomes phosphorylated and induces cell lethality. All these observations indicate that the phosphorelay negatively regulates KlHog1. Nevertheless, in the absence of KlSln1 or KlYpd1, no constitutive phosphorylation is detected and cells are viable, suggesting that a strong negative feedback that is independent of KlPtp2 operates in K. lactis. Compared with S. cerevisiae, K. lactis has only a moderate accumulation of glycerol and fails to produce trehalose under hyperosmotic stress, indicating that regulation of osmolyte production is different in K. lactis.
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Miriam
authors.initials: M
authors.lastname: Rodríguez-González
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Laura
authors.initials: L
authors.lastname: Kawasaki
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Nancy
authors.initials: N
authors.lastname: Velázquez-Zavala
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Eunice
authors.initials: E
authors.lastname: Domínguez-Martín
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Abraham
authors.initials: A
authors.lastname: Trejo-Medecigo
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Natalia
authors.initials: N
authors.lastname: Martagón
authors.affiliation: Departamento de Bioquímica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Emilio
authors.initials: E
authors.lastname: Espinoza-Simón
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Araceli
authors.initials: A
authors.lastname: Vázquez-Ibarra
authors.affiliation: Unidad de Biología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Laura
authors.initials: L
authors.lastname: Ongay-Larios
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Georgellis
authors.affiliation: Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, E-08003, Spain.
authors.forename: Eulàlia
authors.initials: E
authors.lastname: de Nadal
authors.affiliation: Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, E-08003, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Posas
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México.
authors.forename: Roberto
authors.identifier: http://orcid.org/0000-0003-1947-5527
authors.initials: R
authors.lastname: Coria
mesh_terms: D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D007716:Kluyveromyces / Q000378:metabolism*; D009994:Osmolar Concentration; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D015398:Signal Transduction; D013312:Stress, Physiological
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011494:Protein Kinases