title: Bet3 participates in autophagy through GTPase Ypt1 in Saccharomyces cerevisiae.
abstract: Three TRAPP (transport protein particle) complexes have been identified in Saccharomyces cerevisiae. GTPases Ypt1 and Ypt31/32 suppress autophagic defects in the mutants of TRAPPIII-specific subunit (Trs85) and TRAPPII-specific subunits (Trs130 and Trs120), respectively. However, the roles of the common TRAPP subunits (which also form the TRAPPI complex) in autophagy and their relationship to Rab GTPases in autophagy remain unclear. As Bet3 (a common TRAPP subunit) cannot be mutated together with either Trs85 or Trs130, we examined starvation-induced autophagy and the cytoplasm-to-vacuole targeting (Cvt) pathway in bet3ts cells. The results demonstrated that GFP-Atg8 was dispersed in the cytoplasm and Ape1 accumulated as a unique dot on the vacuolar membrane in bet3ts cells. Further analysis revealed that Ape1 maturation and GFP-Atg8 processing are defective in these cells. However, prApe1 (precursor form of Ape1) and GFP-Atg8 are protease-accessible in bet3ts cells under starvation, which indicates that Bet3 functions before autophagosome closure. Furthermore, active Ypt1, but not Ypt31, partly rescued the autophagic defects of bet3ts cells. We conclude that Bet3 is involved in autophagy and propose that it participates in autophagy through TRAPP complexes mostly via Ypt1 in yeast.
authors.affiliation: Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Shenshen
authors.initials: S
authors.lastname: Zou
authors.forename: Yutao
authors.initials: Y
authors.lastname: Liu
authors.forename: Caiyun
authors.initials: C
authors.lastname: Zhang
authors.forename: Sidney
authors.initials: S
authors.lastname: Yu
authors.forename: Yongheng
authors.initials: Y
authors.lastname: Liang
mesh_terms: D000626:Aminopeptidases / Q000378:metabolism; D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009154:Mutation; D011498:Protein Precursors / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C113757:ATG8 protein, S cerevisiae; D000071190:Autophagy-Related Protein 8 Family; C098389:BET3 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D000626:Aminopeptidases; C019689:APE1 protein, S cerevisiae; C087905:YPT31 protein, S cerevisiae; C060755:YPT1 protein, S cerevisiae; C121633:YPT32 protein, S cerevisiae; D020691:rab GTP-Binding Proteins
keywords: Bet3; TRAPP; Ypt1; autophagosome biogenesis; autophagy