title: The MAPk ASTE11 is involved in the maintenance of cell wall integrity and in filamentation in Arxula adeninivorans, but not in adaptation to hypertonic stress.
abstract: In many fungal species, cell growth and morphology, thermo- and osmotolerance are regulated by mitogen-activated protein kinase (MAPk) cascades. Ste11p is a MAP kinase kinase kinase, which plays a central role in various pathways in Saccharomyces cerevisiae. Here we describe ASTE11, an STE11 homologue from Arxula adeninivorans, an imperfect, dimorphic, but nonpathogenic and extremophilic yeast. ASTE11 lacks introns, and codes for a protein of 824 amino acids with a predicted molecular weight of 91.6 kDa. The gene is constitutively expressed at low levels, but is induced by high-salt stress. To facilitate functional analysis of ASTE11, disruption and overexpressing mutants were constructed. The phenotypes of these strains indicate that Aste11p is involved in regulating aspects of cell wall structure and form, but is dispensable for adaptation to hypertonic stress. Despite its structural homology to STE11, ASTE11 cannot complement the mating defect of S. cerevisiae ste11 mutants. These findings emphasize that, although components of MAPk pathways are conserved among yeasts, they often operate in different contexts in different species.
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Gatersleben, Germany.
authors.forename: Erik
authors.initials: E
authors.lastname: Böer
authors.forename: Gamal
authors.initials: G
authors.lastname: El Metabteb
authors.forename: Ayman
authors.initials: A
authors.lastname: El Fiki
authors.forename: Peggy
authors.initials: P
authors.lastname: Brückner
authors.forename: Thomas
authors.initials: T
authors.lastname: Wartmann
authors.forename: Michael
authors.initials: M
authors.lastname: Piontek
authors.forename: Gotthard
authors.initials: G
authors.lastname: Kunze
mesh_terms: D000595:Amino Acid Sequence; D002473:Cell Wall / Q000502:physiology*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018628:Gene Dosage; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D007438:Introns; D020930:MAP Kinase Kinase Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009997:Osmotic Pressure; D010802:Phylogeny; D029701:Saccharomyces cerevisiae Proteins; D004718:Saccharomycetales / Q000201:enzymology / Q000502:physiology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae