PT  - JOURNAL ARTICLE
AU  - Aina Masgrau
AU  - Andrea Battola
AU  - Trinidad Sanmartin
AU  - Leszek P. Pryszcz
AU  - Toni Gabaldón
AU  - Manuel Mendoza
TI  - Distinct roles of the polarity factors Boi1 and Boi2 in the control of exocytosis and abscission in budding yeast
AID  - 10.1101/151670
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 151670
4099  - http://biorxiv.org/content/early/2017/06/18/151670.short
4100  - http://biorxiv.org/content/early/2017/06/18/151670.full
AB  - Boi1 and Boi2 (Boi1/2) are budding yeast plasma membrane proteins that function in polarized growth, and in cytokinesis inhibition in response to chromosome bridges via the NoCut abscission checkpoint. How Boi1/2 act in these two distinct processes is not understood. We demonstrate that Boi1/2 are required for a late step in the fusion of secretory vesicles with the plasma membrane of the growing bud. Cells lacking Boi1/2 accumulate secretory vesicles and are defective in bud growth. In contrast, Boi2 is specifically required for abscission inhibition in cells with chromatin bridges. The SH3 domain of Boi2, which is dispensable for bud growth and targets Boi2 to the site of abscission, is essential for abscission inhibition. Gain of function of the exocyst, a conserved protein complex involved in tethering of exocytic vesicles to the plasma membrane, rescued secretion and bud growth defects in boi mutant cells, and abrogated NoCut checkpoint function. Thus, Boi2 functions redundantly with Boi1 to promote the fusion of secretory vesicles with the plasma membrane at sites of polarized growth, and acts as an abscission inhibitor during cytokinesis in response to chromatin bridges.