8q0g
Release Complex: BAM bound EspP and Compact SurA
Structural highlights
FunctionBAMB_ECOLI Part of the outer membrane protein assembly complex, which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Nonessential member of the complex, which may orient the flexible periplasmic domain of BamA for interaction with other Bam components, chaperones and nascent outer membrane proteins.[1] [2] [3] [4] Publication Abstract from PubMedThe outer membrane is a formidable barrier that protects Gram-negative bacteria against environmental threats. Its integrity requires the correct folding and insertion of outer membrane proteins (OMPs) by the membrane-embedded beta-barrel assembly machinery (BAM). Unfolded OMPs are delivered to BAM by the periplasmic chaperone SurA, but how SurA and BAM work together to ensure successful OMP delivery and folding remains unclear. Here, guided by AlphaFold2 models, we use disulphide bond engineering in an attempt to trap SurA in the act of OMP delivery to BAM, and solve cryoEM structures of a series of complexes. The results suggest that SurA binds BAM at its soluble POTRA-1 domain, which may trigger conformational changes in both BAM and SurA that enable transfer of the unfolded OMP to the BAM lateral gate for insertion into the outer membrane. Mutations that disrupt the interaction between BAM and SurA result in outer membrane assembly defects, supporting the key role of SurA in outer membrane biogenesis. Outer membrane protein assembly mediated by BAM-SurA complexes.,Fenn KL, Horne JE, Crossley JA, Bohringer N, Horne RJ, Schaberle TF, Calabrese AN, Radford SE, Ranson NA Nat Commun. 2024 Sep 1;15(1):7612. doi: 10.1038/s41467-024-51358-x. PMID:39218969[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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