Yeast synaptobrevin, Snc1, engages distinct routes of postendocytic recycling mediated by a sorting nexin, Rcy1-COPI, and retromer.

ABSTRACT: The budding yeast v-SNARE, Snc1, mediates fusion of exocytic vesicles to the plasma membrane (PM) and is subsequently recycled back to the Golgi. Postendocytic recycling of Snc1 requires a phospholipid flippase (Drs2-Cdc50), an F-box protein (Rcy1), a sorting nexin (Snx4-Atg20), and the COPI coat complex. A portion of the endocytic tracer FM4-64 is also recycled back to the PM after internalization. However, the relationship between Snx4, Drs2, Rcy1, and COPI in recycling Snc1 or FM4-64 is unclear. Here we show that rcy1? and drs2? single mutants, or a COPI mutant deficient in ubiquitin binding, display a defect in recycling FM4-64 while snx4? cells recycle FM4-64 normally. The addition of latrunculin A to acutely inhibit endocytosis shows that rcy1? and snx4? single mutants retain the ability to recycle Snc1, but a snx4?rcy1? mutant substantially blocks export. Additional deletion of a retromer subunit completely eliminates recycling of Snc1 in the triple mutant (snx4?rcy1?vps35?). A minor role for retromer in Snc1 recycling can also be observed in single and double mutants harboring vps35?. These data support the existence of three distinct and parallel recycling pathways mediated by Drs2/Rcy1/COPI, Snx4-Atg20, and retromer that retrieve an exocytic v-SNARE from the endocytic pathway to the Golgi.

SUBMITTER: Best JT 

PROVIDER: S-EPMC7185969 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature