Characterization of Protein–Membrane Interactions in Yeast Autophagy

Abstract

Cells rely on autophagy to degrade cytosolic material and maintain homeostasis. During autophagy, content to be degraded is encapsulated in double membrane vesicles, termed autophagosomes, which fuse with the yeast vacuole for degradation. This conserved cellular process requires the dynamic rearrangement of membranes. As such, the process of autophagy requires many soluble proteins that bind to membranes to restructure, tether, or facilitate lipid transfer between membranes. Here, we review the methods that have been used to investigate membrane binding by the core autophagy machinery and additional accessory proteins involved in autophagy in yeast. We also review the key experiments demonstrating how each autophagy protein was shown to interact with membranes.

Autophagy in a Nutshell

“…In vitro data suggest that Atg8 may also provide lipids by homotypic fusion of incoming vesicles in a SNARE‐independent manner [18], yet whether this is the case in vivo remains to be seen. Yeast Atg24 and Atg20 are required for selective autophagy in yeast and localize to the selective PAS [19]. They bind PI(3)P‐positive membranes through a hydrophobic‐basic membrane insertion loop in their phox‐homology (PX) domain, and induce and stabilize membrane curvature by their bent anti‐parallel alpha‐helix bundle Bin/Amphiphysin/Rvs (BAR) domain, which also facilitates their hetero‐dimerization.…”

The Intrinsically Disordered N Terminus in Atg12 from Yeast Is Necessary for the Functional Structure of the Protein

“…Finding that Atg12 IDPR is indispensable for efficient nonselective autophagy (Figure 1B) prompted us to further investigate the role of this region. Many proteins of the autophagy machinery have a domain that allows them to interact with cellular membranes [43,44]. We asked whether the Atg12 IDPR is such a domain.…”