Structural basis of outer membrane protein insertion by the BAM complex

Journal article

All Gram-negative bacteria, mitochondria and chloroplasts have outer membrane proteins (OMPs) that perform many fundamental biological processes. The OMPs in Gram-negative bacteria are inserted and folded into the outer membrane by the β-barrel assembly machinery (BAM). The mechanism involved is poorly understood, owing to the absence of a structure of the entire BAM complex. Here we report two crystal structures of the Escherichia coli BAM complex in two distinct states: an inward-open state and a lateral-open state. Our structures reveal that the five polypeptide transport-associated domains of BamA form a ring architecture with four associated lipoproteins, BamB–BamE, in the periplasm. Our structural, functional studies and molecular dynamics simulations indicate that these subunits rotate with respect to the integral membrane β-barrel of BamA to induce movement of the β-strands of the barrel and promote insertion of the nascent OMP.

Authors: Stansfeld, P; Gu, Y; Li, H; Zeng, Y; Zhang, Z

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Publishing Group
• Journal: Nature
• Volume: 531
• Pages: 64-69
• Publication date: 2016-03-03
• Acceptance date: 2016-02-05
• DOI: 10.1038/nature17199
• EISSN: 1476-4687
• ISSN: 0028-0836
• Keywords: Membrane structure and assembly; Bacterial structural biology; X-ray crystallography