Abreu Susana, Kriegenburg Franziska, Gómez-Sánchez Rubén, Mari Muriel, Sánchez-Wandelmer Jana, Skytte Rasmussen Mads, Soares Guimarães Rodrigo, Zens Bettina, Schuschnig Martina, Hardenberg Ralph, Peter Matthias, Johansen Terje, Kraft Claudine, Martens Sascha, Reggiori Fulvio
Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Department of Cell Biology, University Medical Center Utrecht, Utrecht, The Netherlands.
EMBO Rep. 2017 May;18(5):765-780. doi: 10.15252/embr.201643146. Epub 2017 Mar 22.
Deconjugation of the Atg8/LC3 protein family members from phosphatidylethanolamine (PE) by Atg4 proteases is essential for autophagy progression, but how this event is regulated remains to be understood. Here, we show that yeast Atg4 is recruited onto autophagosomal membranes by direct binding to Atg8 via two evolutionarily conserved Atg8 recognition sites, a classical LC3-interacting region (LIR) at the C-terminus of the protein and a novel motif at the N-terminus. Although both sites are important for Atg4-Atg8 interaction , only the new N-terminal motif, close to the catalytic center, plays a key role in Atg4 recruitment to autophagosomal membranes and specific Atg8 deconjugation. We thus propose a model where Atg4 activity on autophagosomal membranes depends on the cooperative action of at least two sites within Atg4, in which one functions as a constitutive Atg8 binding module, while the other has a preference toward PE-bound Atg8.
自噬体进展过程中，Atg4蛋白酶将Atg8/LC3蛋白家族成员与磷脂酰乙醇胺（PE）解偶联至关重要，但该过程如何被调控仍有待了解。在此，我们表明酵母Atg4通过两个进化上保守的Atg8识别位点直接与Atg8结合，从而被招募到自噬体膜上，一个是位于该蛋白C端的经典LC3相互作用区域（LIR），另一个是位于N端的新基序。虽然这两个位点对于Atg4与Atg8的相互作用都很重要，但只有靠近催化中心的新N端基序在Atg4被招募到自噬体膜以及特定的Atg8解偶联过程中起关键作用。因此，我们提出了一个模型，其中自噬体膜上的Atg4活性取决于Atg4内至少两个位点的协同作用，其中一个作为组成型Atg8结合模块，而另一个则更倾向于与PE结合的Atg8。
