title: Coregulation of starch degradation and dimorphism in the yeast Saccharomyces cerevisiae.
abstract: Saccharomyces cerevisiae, the exemplar unicellular eukaryote, can only survive and proliferate in its natural habitats through constant adaptation within the constraints of a dynamic ecosystem. In every cell cycle of S. cerevisiae, there is a short period in the G1 phase of the cell cycle where "sensing" transpires; if a sufficient amount of fermentable sugars is available, the cells will initiate another round of vegetative cell division. When fermentable sugars become limiting, the yeast can execute the diauxic shift, where it reprograms its metabolism to utilize nonfermentable carbon sources. S. cerevisiae can also initiate the developmental program of pseudohyphal formation and invasive growth response, when essential nutrients become limiting. S. cerevisiae shares this growth form-switching ability with important pathogens such as the human pathogen, Candida albicans, and the corn smut pathogen Ustilago maydis. The pseudohyphal growth response of S. cerevisiae has mainly been implicated as a means for the yeast to search for nutrients. An important observation made was that starch-degrading S. cerevisiae strains have the added ability to form pseudohyphae and grow invasively into a starch-containing medium. More significantly, it was also shown that the STA1-3 genes encoding three glucoamylase isozymes responsible for starch hydrolysis in S. cerevisiae are coregulated with a gene, MUC1, essential for pseudohyphal and invasive growth. At least two putative transcriptional activators, Mss10p and Mss11p, are involved in this regulation. The Muc1p is a putative integral membrane-bound protein similar to mammalian mucin-like proteins that have been implicated in the ability of cancer cells to invade other tissues. This provided us with an excellent example of integrative control between nutrient sensing, signaling, and differential development.
authors.affiliation: Institute for Wine Biotechnology, University of Stellenbosch, South Africa.
authors.forename: M A
authors.initials: MA
authors.lastname: Vivier
authors.forename: M G
authors.initials: MG
authors.lastname: Lambrechts
authors.forename: I S
authors.initials: IS
authors.lastname: Pretorius
mesh_terms: D000222:Adaptation, Physiological; D002244:Carbon / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D015825:Chromosomes, Fungal / Q000235:genetics; D000242:Cyclic AMP / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016193:G1 Phase / Q000502:physiology; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D017874:Immediate-Early Proteins; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology; D008954:Models, Biological; D009004:Monosaccharide Transport Proteins / Q000502:physiology; D018396:Mucin-1 / Q000235:genetics / Q000502:physiology; D011393:Procollagen-Proline Dioxygenase; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013213:Starch / Q000378:metabolism*; D014157:Transcription Factors; D018631:ras Proteins / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D017874:Immediate-Early Proteins; D007527:Isoenzymes; C490188:MSN1 protein, S cerevisiae; C109358:MSS11 protein, S cerevisiae; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D018396:Mucin-1; C104463:SNF3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D002244:Carbon; D013213:Starch; D000242:Cyclic AMP; C490190:EGLN1 protein, human; D011393:Procollagen-Proline Dioxygenase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; D005087:Glucan 1,4-alpha-Glucosidase; C109934:SGA1 protein, S cerevisiae; D018631:ras Proteins