Premium
Atg23 and Atg27 Act at the Early Stages of Atg9 Trafficking in S. cerevisiae
Author(s) -
Backues Steven K.,
Orban Daniel P.,
Bernard Amélie,
Singh Kushal,
Cao Yang,
Klionsky Daniel J.
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.12240
Subject(s) - microbiology and biotechnology , autophagy , biology , autophagosome , transmembrane protein , transport protein , retromer , vesicular transport proteins , endosome , receptor , genetics , intracellular , apoptosis , vacuolar protein sorting
Atg9 is a conserved multipass transmembrane protein with an essential role in autophagy. In Saccharomyces cerevisiae , it travels through the secretory pathway to a unique compartment, the Atg9 peripheral structures. These structures are then targeted to the phagophore assembly site (PAS), where they are proposed to help deliver membrane to the forming autophagosome. We used ‘ in vivo reconstitution’ of this process in a multiple‐knockout strain to define four proteins, Atg11, Atg19, Atg23 and Atg27, as the core minimal machinery necessary and sufficient for the trafficking of Atg9 to the PAS. Atg23 and Atg27 function in the formation of the Atg9 peripheral structures. Overexpression of Atg9 can bypass the need for Atg23, suggesting that the amount of Atg9 in each peripheral structure is a critical factor in their targeting to the PAS. In contrast, overexpression of Atg23 or Atg27 interferes with Atg9 trafficking, suggesting that these proteins must be present in the appropriate stoichiometry in order to function properly. These data allow us to resolve existing controversies regarding the role of Atg23 and Atg27, and propose a model that ties together previous observations regarding the role of Atg9 in autophagosome formation.