9i78

Cryo-EM structure of Chaetomium thermophilum ribosome-bound SND3 translocon

spinqualitylabelsall models 9i78, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9i78 is a 10 chain structure with sequence from Chaetomium thermophilum var. thermophilum DSM 1495. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.2Å Ligands: ACE, MG, OMG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function G0S5M5_CHATD Publication Abstract from PubMed During the biogenesis of most eukaryotic integral membrane proteins (IMPs), transmembrane domains are inserted into the endoplasmic reticulum membrane by a dedicated insertase or the SEC61 translocon. The SRP-independent (SND) pathway is the least understood route into the membrane, despite catering for a broad range of IMP types. Here, we show that Chaetomium thermophilum SND3 is a membrane insertase with an atypical fold. We further present a cryo-electron microscopy structure of a ribosome-associated SND3 translocon complex involved in co-translational IMP insertion. The structure reveals that the SND3 translocon additionally comprises the complete SEC61 translocon, CCDC47 and TRAPa. Here, the SEC61beta N-terminus works together with CCDC47 to prevent substrate access to the translocon. Instead, molecular dynamics simulations show that SND3 disrupts the lipid bilayer to promote IMP insertion via its membrane-embedded hydrophilic groove. Structural and sequence comparisons indicate that the SND3 translocon is a distinct multipass translocon in fungi, euglenozoan parasites and other eukaryotic taxa. SND3 is the membrane insertase within a distinct SEC61 translocon complex.,Yang TJ, Mukherjee S, Langer JD, Hummer G, McDowell MA Nat Commun. 2025 Oct 29;16(1):9566. doi: 10.1038/s41467-025-65357-z. PMID:41162385 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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