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Atg27 Tyrosine Sorting Motif is Important for Its Trafficking and Atg9 Localization
Author(s) -
Segarra Verónica A.,
Boettner Douglas R.,
Lemmon Sandra K.
Publication year - 2015
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/tra.12253
Subject(s) - endosome , microbiology and biotechnology , vacuole , retromer , vacuolar protein sorting , biology , transport protein , golgi apparatus , autophagy , transmembrane protein , protein targeting , membrane protein , cytoplasm , intracellular , membrane , biochemistry , endoplasmic reticulum , receptor , apoptosis
During autophagy, the transmembrane protein Atg27 facilitates transport of the major autophagy membrane protein Atg9 to the preautophagosomal structure ( PAS ). To better understand the function of Atg27 and its relationship with Atg9, Atg27 trafficking and localization were examined. Atg27 localized to endosomes and the vacuolar membrane, in addition to previously described PAS , Golgi and Atg9‐positive structures. Atg27 vacuolar membrane localization was dependent on the adaptor AP ‐3, which mediates direct transport from the trans‐Golgi to the vacuole. The four C‐terminal amino acids ( YSAV ) of Atg27 comprise a tyrosine sorting motif. Mutation of the YSAV abrogated Atg27 transport to the vacuolar membrane and affected its distribution in TGN /endosomal compartments, while PAS localization was normal. Also, in atg27(Δ YSAV ) or AP ‐3 mutants, accumulation of Atg9 in the vacuolar lumen was observed upon autophagy induction. Nevertheless, PAS localization of Atg9 was normal in atg27(Δ YSAV ) cells. The vacuole lumen localization of Atg9 was dependent on transport through the multivesicular body, as Atg9 accumulated in the class E compartment and vacuole membrane in atg27(Δ YSAV ) vps4Δ but not in ATG27 vps4Δ cells. We suggest that Atg27 has an additional role to retain Atg9 in endosomal reservoirs that can be mobilized during autophagy.