Tagging morphogenetic genes by insertional mutagenesis in the yeast Yarrowia lipolytica.
The yeast Yarrowia lipolytica is distantly related to Saccharomyces cerevisiae, can be genetically modified, and can grow in both haploid and diploid states in either yeast, pseudomycelial, or mycelial forms, depending on environmental conditions. Previous results have indicated that the STE and RIM pathways, which mediate cellular switching in other dimorphic yeasts, are not required for Y. lipolytica morphogenesis. To identify the pathways involved in morphogenesis, we mutagenized a wild-type strain of Y. lipolytica with a Tn3 derivative. We isolated eight tagged mutants, entirely defective in hyphal formation, from a total of 40,000 mutants and identified seven genes homologous to S. cerevisiae CDC25, RAS2, BUD6, KEX2, GPI7, SNF5, and PPH21. We analyzed their abilities to invade agar and to form pseudomycelium or hyphae under inducing conditions and their sensitivity to temperature and to Calcofluor white. Chitin staining was used to detect defects in their cell walls. Our results indicate that a functional Ras-cyclic AMP pathway is required for the formation of hyphae in Y. lipolytica and that perturbations in the processing of extracellular, possibly parietal, proteins result in morphogenetic defects.
Richard
M
M
Laboratoire de Génétique Moléculaire et Cellulaire, Institut National Agronomique Paris-Grignon, UMR-INRA216, URA-CNRS1925, 78850 Thiverval-Grignon, France. richard@grignon.inra.fr
Quijano
R R
RR
Bezzate
S
S
Bordon-Pallier
F
F
Gaillardin
C
C
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D016254:Mutagenesis, Insertional; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015003:Yeasts / Q000235:genetics* / Q000254:growth & development*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism; D020666:ras-GRF1 / Q000235:genetics / Q000378:metabolism
D018797:Cell Cycle Proteins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C108764:HOY1 protein, Yarrowia lipolytica; D018398:Homeodomain Proteins; D008840:Microfilament Proteins; C085984:PHD1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D020666:ras-GRF1; C489015:RAS2 protein, S cerevisiae; D018631:ras Proteins