5v6p | pdb_00005v6p

CryoEM structure of the ERAD-associated E3 ubiquitin-protein ligase HRD1

Loading... Status: waiting for Mol* initialization Structural highlights 5v6p is a 2 chain structure with sequence from Baker's yeast. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 5v7v Gene: HRD1, DER3, YOL013C (Baker's yeast) Activity: RING-type E3 ubiquitin transferase, with EC number 2.3.2.27 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [HRD1_YEAST] E3 ubiquitin-protein ligase which accepts ubiquitin specifically from endoplasmic reticulum-associated UBC1 and UBC7 E2 ligases, and transfers it to substrates promoting their degradation. Mediates the degradation of endoplasmic reticulum proteins (ERQC), also called ER-associated degradation (ERAD). Component of the HRD1 ubiquitin ligase complex, which is part of the ERAD-L and ERAD-M pathways responsible for the rapid degradation of soluble lumenal and membrane proteins with misfolded lumenal domains (ERAD-L), or ER-membrane proteins with misfolded transmembrane domains (ERAD-M). ERAD-L substrates are ubiquitinated through HRD1 in conjunction with the E2 ubiquitin-conjugating enzymes UBC1 and UBC7-CUE1. Ubiquitinated substrates are then removed to the cytosol via the action of the UFD1-NPL4-CDC48/p97 (UNC) AAA ATPase complex and targeted to the proteasome. ERAD-M substrates are processed by the same HRD1-HRD3 core complex, but only a subset of the other components is required for ERAD-M. Publication Abstract from PubMed Misfolded endoplasmic reticulum proteins are retro-translocated through the membrane into the cytosol, where they are poly-ubiquitinated, extracted from the membrane, and degraded by the proteasome-a pathway termed endoplasmic reticulum-associated protein degradation (ERAD). Proteins with misfolded domains in the endoplasmic reticulum lumen or membrane are discarded through the ERAD-L and ERAD-M pathways, respectively. In Saccharomyces cerevisiae, both pathways require the ubiquitin ligase Hrd1, a multi-spanning membrane protein with a cytosolic RING finger domain. Hrd1 is the crucial membrane component for retro-translocation, but it is unclear whether it forms a protein-conducting channel. Here we present a cryo-electron microscopy structure of S. cerevisiae Hrd1 in complex with its endoplasmic reticulum luminal binding partner, Hrd3. Hrd1 forms a dimer within the membrane with one or two Hrd3 molecules associated at its luminal side. Each Hrd1 molecule has eight transmembrane segments, five of which form an aqueous cavity extending from the cytosol almost to the endoplasmic reticulum lumen, while a segment of the neighbouring Hrd1 molecule forms a lateral seal. The aqueous cavity and lateral gate are reminiscent of features of protein-conducting conduits that facilitate polypeptide movement in the opposite direction-from the cytosol into or across membranes. Our results suggest that Hrd1 forms a retro-translocation channel for the movement of misfolded polypeptides through the endoplasmic reticulum membrane. Cryo-EM structure of the protein-conducting ERAD channel Hrd1 in complex with Hrd3.,Schoebel S, Mi W, Stein A, Ovchinnikov S, Pavlovicz R, DiMaio F, Baker D, Chambers MG, Su H, Li D, Rapoport TA, Liao M Nature. 2017 Aug 17;548(7667):352-355. doi: 10.1038/nature23314. Epub 2017 Jul 6. PMID:28682307 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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