Exit from mitosis triggers Chs2p transport from the endoplasmic reticulum to mother-daughter neck via the secretory pathway in budding yeast.
Budding yeast chitin synthase 2 (Chs2p), which lays down the primary septum, localizes to the mother-daughter neck in telophase. However, the mechanism underlying the timely neck localization of Chs2p is not known. Recently, it was found that a component of the exocyst complex, Sec3p-green fluorescent protein, arrives at the neck upon mitotic exit. It is not clear whether the neck localization of Chs2p, which is a cargo of the exocyst complex, was similarly regulated by mitotic exit. We report that Chs2p was restrained in the endoplasmic reticulum (ER) during metaphase. Furthermore, mitotic exit was sufficient to cause Chs2p neck localization specifically by triggering the Sec12p-dependent transport of Chs2p out of the ER. Chs2p was "forced" prematurely to the neck by mitotic kinase inactivation at metaphase, with chitin deposition occurring between mother and daughter cells. The dependence of Chs2p exit from the ER followed by its transport to the neck upon mitotic exit ensures that septum formation occurs only after the completion of mitotic events.
Zhang
Gang
G
Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597.
Kashimshetty
Rohini
R
Ng
Kwee Eng
KE
Tan
Heng Buck
HB
Yeong
Foong May
FM
D018797:Cell Cycle Proteins / Q000378:metabolism; D002686:Chitin / Q000378:metabolism; D002687:Chitin Synthase / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D008938:Mitosis; D009154:Mutation / Q000235:genetics; D010770:Phosphotransferases / Q000378:metabolism; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D004718:Saccharomycetales / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D013692:Telophase / Q000235:genetics*; D043324:beta-Fructofuranosidase / Q000378:metabolism
C082279:CDC15 protein; D018797:Cell Cycle Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D002686:Chitin; D002687:Chitin Synthase; C400821:chitin synthase 2; D010770:Phosphotransferases; D043324:beta-Fructofuranosidase; D019204:GTP-Binding Proteins