Filamentous growth of the budding yeast Saccharomyces cerevisiae induced by overexpression of the WHi2 gene.
The WHI2 gene of the budding yeast Saccharomyces cerevisiae is required for the arrest of cell proliferation upon nutrient exhaustion: whi2 mutants carry on dividing and in the absence of growth become abnormally small. It is reported here that overexpression of Whi2 from the GAL1 promoter results in filamentous growth - cells fail to complete cytokinesis, the budding pattern changes from axial to polar, cells become elongated and cell size increases threefold. In many ways, these filaments resemble the pseudohyphae which result from nitrogen-limited growth and the filaments seen during the invasive growth of haploids. However, Whi2-induced filament formation is reduced, but not blocked, by mutations in STE7, STE12 or STE20 which do block pseudohypha formation. Furthermore, pseudohypha formation can still occur in a diploid in which both copies of the WHI2 gene have been deleted. Thus Whi2-induced filament formation and pseudohypha formation must come about through the action of different pathways. Despite this, a mutation in the STE11 gene, which is required for pseudohypha formation, does block Whi2-induced filament formation. Concanavalin A pulse-chase experiments show that new cell wall material is incorporated only into the tips of the apical cells. An extragenic suppressor of the Whi2 allele also results in filamentous growth. These results suggest that Whi2 negatively regulates a function required for the budding mode of cell proliferation including cytokinesis. This function is defined wholly or in part by the fsw1 allele.
Radcliffe
P A
PA
Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Binley
K M
KM
Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Trevethick
J
J
Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Hall
M
M
Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Sudbery
P E
PE
Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D000939:Epitopes / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics*; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000502:physiology; D009154:Mutation / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors
D018797:Cell Cycle Proteins; D000939:Epitopes; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C489241:STE12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C071596:ste11 protein, S pombe; D017346:Protein Serine-Threonine Kinases; D020930:MAP Kinase Kinase Kinases; C078754:STE20 protein, S cerevisiae; C067018:Ste11 protein, S cerevisiae