7TT6

BamABCDE bound to substrate EspP in the intermediate-open EspP state

Summary for 7TT6

• Entry DOI: 10.2210/pdb7tt6/pdb
• Related: 7TSZ 7TT0 7TT1 7TT2 7TT3 7TT4 7TT5 7TT6 7TT7
• EMDB information: 26105 26106 26107 26108 26109 26110 26111 26112 26113
• Descriptor: Maltose/maltodextrin-binding periplasmic protein,Serine protease EspP chimera, Outer membrane protein assembly factor BamA, Outer membrane protein assembly factor BamC, ... (5 entities in total)
• Functional Keywords: membrane protein folding, membrane dynamics, outer membrane protein, bam, beta-barrel, membrane protein
• Biological source: Escherichia coli; More
• Total number of polymer chains: 5
• Total formula weight: 243789.70

Authors

Doyle, M.T.,Jimah, J.R.,Dowdy, T.,Ohlemacher, S.I.,Larion, M.,Hinshaw, J.E.,Bernstein, H.D. (deposition date: 2022-01-31, release date: 2022-03-30, Last modification date: 2022-04-13)

Primary citation

Doyle, M.T.,Jimah, J.R.,Dowdy, T.,Ohlemacher, S.I.,Larion, M.,Hinshaw, J.E.,Bernstein, H.D.
Cryo-EM structures reveal multiple stages of bacterial outer membrane protein folding.
Cell, 185:1143-, 2022

PubMed Abstract: Transmembrane β barrel proteins are folded into the outer membrane (OM) of Gram-negative bacteria by the β 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 β barrel protein (EspP) by BAM. We found that BAM binds the highly conserved "β signal" motif of EspP to correctly orient β strands in the OM during folding. We also found that the folding of EspP proceeds via "hybrid-barrel" intermediates in which membrane integrated β 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 β sheets progressively fold toward BamA to form a β barrel. Along with in vivo experiments that tracked β barrel folding while the OM tension was modified, our results support a model in which BAM harnesses OM elasticity to accelerate β barrel folding.

PubMed: 35294859
DOI: 10.1016/j.cell.2022.02.016

Experimental method

ELECTRON MICROSCOPY (4.3 Å)