title: Analysis of the cell wall integrity pathway of Ashbya gossypii.
abstract: Fungal cells are exposed to rapidly changing environmental conditions, in particular with regard to the osmotic potential. This requires constant remodeling of the cell wall and, therefore, the cell wall integrity (CWI) MAP-kinase pathway plays a major role in shaping the fungal cell wall to protect from adverse external stresses. To provide a comprehensive functional analysis of the Ashbya gossypii CWI pathway we generated a set of ten deletion mutants in conserved components including the cell surface sensors AgWSC1 and AgMID2, a putative Rho1-guanine nucleotide exchange factor, AgTUS1, the protein kinase C, AgPKC1, the MAP-kinases AgBCK1, AgMKK1 and AgMPK1, and transcription factors known to be involved in CWI signaling AgRLM1, AgSWI4 and AgSWI6. Deletion of AgPKC1 shows a severe growth defect with frequent tip cell lysis. Deletion of components of the MAP-kinase module generates a pronounced colony lysis phenotype in older regions of the mycelium. Cytoplasmic leakage was assayed using alkaline phosphatase and β-galactosidase release assays. This indicated that the lysis phenotypes of CWI pathway mutants may be useful to facilitate the isolation of riboflavin from A. gossypii. Remarkably, the Agwsc1 mutant showed a strong (up to 8-fold) increase of riboflavin in the growth medium compared to the parental strain.
authors.affiliation: Carlsberg Laboratory, Yeast Genetics, Gamle Carlsberg Vej 10, DK-1799 Copenhagen V, Denmark.
authors.forename: Klaus B
authors.initials: KB
authors.lastname: Lengeler
authors.forename: Lisa
authors.initials: L
authors.lastname: Wasserstrom
authors.forename: Andrea
authors.initials: A
authors.lastname: Walther
authors.forename: Jürgen
authors.initials: J
authors.lastname: Wendland
mesh_terms: D000222:Adaptation, Physiological; D002473:Cell Wall / Q000235:genetics / Q000502:physiology*; D003470:Culture Media / Q000737:chemistry; D055169:Eremothecium / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D012256:Riboflavin / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D012256:Riboflavin
keywords: Cell lysis; MAP kinase cascade; Osmotic stress; Riboflavin; Signaling