6a9e
From Proteopedia
Crystal structure of the N-terminal domain of Atg2
Structural highlights
FunctionENLYS_BPT4 Endolysin with lysozyme activity that degrades host peptidoglycans and participates with the holin and spanin proteins in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles. Once the holin has permeabilized the host cell membrane, the endolysin can reach the periplasm and break down the peptidoglycan layer.[1] ATG2_SCHPO Lipid transfer protein required for autophagosomes completion and peroxisome degradation (PubMed:16303567, PubMed:30911189). Tethers the edge of the isolation membrane (IM) to the endoplasmic reticulum (ER) and mediates direct lipid transfer from ER to IM for IM expansion (PubMed:30911189). Atg2 binds to the ER exit site (ERES), which is the membrane source for autophagosome formation, using basic residues in its N-terminal region (NR) and to the expanding edge of the IM through its C-terminal region (PubMed:30911189). The latter binding is assisted by an atg18-PtdIns3P interaction (PubMed:30911189). Atg2 then extracts phospholipids from the membrane source using its NR and transfers them to atg9 to the IM through its predicted beta-sheet-rich structure for membrane expansion (PubMed:30911189). Atg2 is also involved in the recruitment of lipids to a restricted region close to the vacuole, termed the vacuole-isolation membrane contact site (VICS), which is also essential for autophagosome formation (By similarity). May have a role in sporulation (PubMed:16303567).[UniProtKB:P53855][2] [3] Publication Abstract from PubMedA key event in autophagy is autophagosome formation, whereby the newly synthesized isolation membrane (IM) expands to form a complete autophagosome using endomembrane-derived lipids. Atg2 physically links the edge of the expanding IM with the endoplasmic reticulum (ER), a role that is essential for autophagosome formation. However, the molecular function of Atg2 during ER-IM contact remains unclear, as does the mechanism of lipid delivery to the IM. Here we show that the conserved amino-terminal region of Schizosaccharomyces pombe Atg2 includes a lipid-transfer-protein-like hydrophobic cavity that accommodates phospholipid acyl chains. Atg2 bridges highly curved liposomes, thereby facilitating efficient phospholipid transfer in vitro, a function that is inhibited by mutations that impair autophagosome formation in vivo. These results suggest that Atg2 acts as a lipid-transfer protein that supplies phospholipids for autophagosome formation. Atg2 mediates direct lipid transfer between membranes for autophagosome formation.,Osawa T, Kotani T, Kawaoka T, Hirata E, Suzuki K, Nakatogawa H, Ohsumi Y, Noda NN Nat Struct Mol Biol. 2019 Apr;26(4):281-288. doi: 10.1038/s41594-019-0203-4. Epub, 2019 Mar 25. PMID:30911189[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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