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| Title | Substrate-induced assembly and functional mechanism of the membrane protein insertase SecYEG-YidC. |
|---|---|
| Journal, issue, pages | Embo J., Year 2026 |
| Publish date | Nov 6, 2025 |
 Authors | Max Busch / Cristian Rosales-Hernandez / Michael Kamel / Yulia Schaumkessel / Eli O van der Sluis / Otto Berninghausen / Thomas Becker / Roland Beckmann / Alexej Kedrov /   |
| PubMed Abstract | The Sec translocon and the YidC/Oxa1-type insertases universally mediate biogenesis of α-helical membrane proteins, but the molecular basis of their cooperation has remained disputed. Recent ...The Sec translocon and the YidC/Oxa1-type insertases universally mediate biogenesis of α-helical membrane proteins, but the molecular basis of their cooperation has remained disputed. Recent discovery of multi-subunit insertases assembled at the back of the translocon in fungi and higher eukaryotes has raised questions about the architecture and mechanism of the putative bacterial ortholog SecYEG-YidC. Here, we combine cryogenic electron microscopy with cell-free protein synthesis to visualize biogenesis of the SecYEG/YidC-dependent multipass membrane protein NuoK. The nascent chain of NuoK does not enter the lateral gate of SecYEG but instead crosses the translocon towards its back side, where YidC is recruited in the nascent substrate-dependent manner. The SecY-YidC interface promotes folding of the transmembrane helices before insertion, consistent with thermodynamic principles of membrane protein folding. YidC forms extensive contacts with the nascent chain, suggesting its key role in the insertion event. These findings provide mechanistic insight into membrane protein insertases, support evolutionary conservation of a gate-independent insertion route, and expand current models of membrane protein biogenesis. |
 External links | Embo J. / PubMed:42362696 |
| Methods | EM (single particle) |
| Resolution | 2.44 - 3.76 Å |
| Structure data |  EMDB-53560: Structure of a stalled E. coli 70S RNC-NuoK-48 in complex with the SecYEG Translocon.  EMDB-53568: Structure of a stalled E. coli 70S RNC-NuoK-48 in complex with the SecYEG Translocon (Focused Refinement)  EMDB-53584: Structure of a stalled E. coli 70S RNC-NuoK-86-E36K-E76K-mutant in complex with the SecYEG-YidC membrane protein insertase  EMDB-53585: Structure of a stalled E. coli 70S RNC-NuoK-86-E36K-E76K-mutant in complex with the SecYEG-YidC membrane protein insertase (Focused Refinement)  EMDB-53587: Structure of a stalled E. coli 70S RNC-NuoK-86 in complex with the SecYEG-YidC membrane protein insertase  EMDB-53589: Structure of a stalled E. coli 70S RNC-NuoK-86 in complex with the SecYEG-YidC membrane protein insertase (Focused Refinement) EMDB-53892, PDB-9rbf:  EMDB-53893: Structure of a stalled E. coli 70S RNC-NuoK-86 in complex with the membrane protein insertase SecYEG-YidC (Focused Refinement)  EMDB-53894: Structure of a stalled E. coli 70S RNC-NuoK-86 in complex with the membrane protein insertase SecYEG-YidC (Composite map) 
EMDB-55568: Structure of a stalled E. coli 70S RNC-NuoK-86 in complex with SecYEG (Consensus Refinement)
EMDB-55570: Structure of a stalled E. coli 70S RNC-NuoK-70 in complex with SecYEG-YidC (Consensus Refinement)
EMDB-55571: Structure of a stalled E. coli 70S RNC-NuoK-70 in complex with SecYEG-YidC (Focused Refinement) EMDB-55598, PDB-9t5x: |
| Chemicals |  ChemComp-ZN:  ChemComp-MG:  ChemComp-PRO:  ChemComp-SPM:  ChemComp-PRI: |
| Source |
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 Keywords | PROTEIN TRANSPORT / 70S Ribosome / SecYEG translocon / YidC / NuoK |
escherichia coli (E. coli)