Morphogenesis beyond cytokinetic arrest in Saccharomyces cerevisiae.
The budding yeast lyt1 mutation causes cell lysis. We report here that lyt1 is an allele of cdc15, a gene which encodes a protein kinase that functions late in the cell cycle. Neither cdc15-1 nor cdc15-lyt1 strains are able to septate at 37 degreesC, even though they may manage to rebud. Cells lyse after a shmoo-like projection appears at the distal pole of the daughter cell. Actin polarizes towards the distal pole but the septins remain at the mother-daughter neck. This morphogenetic response reflects entry into a new round of the cell cycle: the preference for polarization from the distal pole was lost in bud1 cdc15 double mutants; double cdc15-lyt1 cdc28-4 mutants, defective for START, did not develop apical projections and apical polarization was accompanied by DNA replication. The same phenomena were caused by mutations in the genes CDC14, DBF2, and TEM1, which are functionally related to CDC15. Apical polarization was delayed in cdc15 mutants as compared with budding in control cells and this delay was abolished in a septin mutant. Our results suggest that the delayed M/G1 transition in cdc15 mutants is due to a septin-dependent checkpoint that couples initiation of the cell cycle to the completion of cytokinesis.
Jiménez
J
J
Departamento de Microbiología II, Facultad de Farmacia.
Cid
V J
VJ
Cenamor
R
R
Yuste
M
M
Molero
G
G
Nombela
C
C
Sánchez
M
M
D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics; D002455:Cell Division; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004261:DNA Replication; D005656:Fungal Proteins / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics; D005800:Genes, Fungal; D005838:Genotype; D007700:Kinetics; D008938:Mitosis; D008954:Models, Biological; D020559:Monomeric GTP-Binding Proteins; D009024:Morphogenesis; D016296:Mutagenesis; D016366:Open Reading Frames; D011494:Protein Kinases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases; D017027:Protein Tyrosine Phosphatases; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction
C074860:CDC14 protein, S cerevisiae; C082279:CDC15 protein; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C089965:TEM1 protein, S cerevisiae; D011494:Protein Kinases; C085768:DBF2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D017027:Protein Tyrosine Phosphatases; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins