Secretion is required for late events in the cell-fusion pathway of mating yeast.
Secretory vesicles accumulate adjacent to the contact site between the two cells of a yeast mating pair before they fuse, but there is no direct evidence that secretion is required to complete fusion. In this study, temperature-sensitive secretion (sec(ts)) mutants were used to investigate the role of secretion in yeast cell fusion. Cell fusion arrested less than 5 minutes after inhibiting secretion. This rapid fusion arrest was not an indirect consequence of reduced mating pheromone signaling, mating-pair assembly or actin polarity. Furthermore, secretion was required to complete cell fusion when it was transiently inhibited by addition and removal of the lipophilic styryl dye, FM4-64. These results indicate that ongoing secretion is required for late events in the cell-fusion pathway, which include plasma-membrane fusion and the completion of cell-wall remodeling, and they demonstrate a just-in-time delivery mechanism for the cell-fusion machinery.
Grote
Eric
E
Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205. egrote@jhsph.edu
D002478:Cells, Cultured; D005816:Genetic Complementation Test; D008561:Membrane Fusion / Q000187:drug effects / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics; D009154:Mutation / Q000235:genetics; D011726:Pyridinium Compounds / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012098:Reproduction; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D055571:Secretory Pathway; D022142:Secretory Vesicles / Q000378:metabolism*; D013696:Temperature; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts / Q000502:physiology*; D001616:beta-Galactosidase / Q000378:metabolism*
C092350:FM 4-64; C490024:FUS1 protein, S cerevisiae; D008565:Membrane Proteins; C499613:PRM1 protein, S cerevisiae; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; C490684:SEC6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D001616:beta-Galactosidase