7tt1
From Proteopedia
BamABCDE bound to substrate EspP class 4
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 PubMedTransmembrane beta barrel proteins are folded into the outer membrane (OM) of Gram-negative bacteria by the beta barrel assembly machinery (BAM) via a poorly understood process that occurs without known external energy sources. Here, we used single-particle cryo-EM to visualize the folding dynamics of a model beta barrel protein (EspP) by BAM. We found that BAM binds the highly conserved "beta signal" motif of EspP to correctly orient beta strands in the OM during folding. We also found that the folding of EspP proceeds via "hybrid-barrel" intermediates in which membrane integrated beta sheets are attached to the essential BAM subunit, BamA. The structures show an unprecedented deflection of the membrane surrounding the EspP intermediates and suggest that beta sheets progressively fold toward BamA to form a beta barrel. Along with in vivo experiments that tracked beta barrel folding while the OM tension was modified, our results support a model in which BAM harnesses OM elasticity to accelerate beta barrel folding. , PMID:35294859[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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