Structural basis of outer membrane protein insertion by the BAM complex

Yinghong Gu, Huanyu Li, Haohao Dong, Yi Zeng, Zhengyu Zhang, Neil G. Paterson, Phillip J Stansfeld, Zhongshan Wang, Yizheng Zhang, Wenjian Wang, Changjiang Dong

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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.
Original languageEnglish
Pages (from-to)64–69
Number of pages6
Early online date22 Feb 2016
Publication statusPublished - 3 Mar 2016


  • X-ray crystallography
  • Bacterial structural biology
  • Membrane structure and assembly

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