Structural insights into the role of BamA in the biogenesis of beta-barrel membrane proteins in Gram-negative bacteria

Trevor James Lithgow, Nicholas Noinaj, Adam J Kuszak, James C Gumbart, Petra Lukacik, Hoshing Chang, Nicole C Easley, Susan K Buchanan

Research output: Contribution to conferenceAbstract

Abstract

The mechanism for integration of α-helical membrane proteins into membranes has been well established. However, the mechanism for insertion of β-barrel membrane proteins, a unique type of membrane protein that can only be found in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts, remains elusive. For Gram-negative bacteria, a five-component complex called the β-barrel assembly machinery (BAM) complex is required for membrane integration. To understand the mechanism of the BAM complex, we have determined crystal structures of BamA, a β-barrel membrane protein itself, in two different conformations representing open and closed states. The structure of BamA contains a C-terminal β-barrel domain consisting of 16-strands and a large periplasmic domain which sits in close proximity to the periplasmic face of the β-barrel domain in the closed state. Our studies suggest that BamA may function by priming the local membrane for insertion and may even undergo a lateral opening event during protein insertion. This work is supported by the Intramural Research Program of the NIH, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892.
Original languageEnglish
Publication statusPublished - 1 Apr 2013

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