Conformational flexibility of the protein insertase BamA in the native asymmetric bilayer elucidated with ESR spectroscopy

Aathira Gopinath, Benesh Joseph
2021 Angewandte Chemie International Edition  
The β-barrel assembly machinery (BAM) consisting of the central β-barrel BamA and four other lipoproteins mediates folding of majority of the outer membrane proteins. BamA is placed in an asymmetric bilayer and its lateral gate is suggested to be the functional hotspot. Here we used in situ pulsed electron-electron double resonance spectroscopy to characterize BamA in the native outer membrane. In the detergent micelles, the data is consistent with mainly an inward-open conformation of BamA.
more » ... native membrane considerably enhanced the conformational heterogeneity. The lateral gate and the extracellular loop 3 exist in an equilibrium between different conformations. The outer membrane provides a favorable environment for occupying multiple conformational states independent of the lipoproteins. Our results reveal a highly dynamic behavior of the lateral gate and other key structural elements and provide direct evidence for the conformational modulation of a membrane protein in situ .
doi:10.1002/anie.202113448 pmid:34761852 pmcid:PMC9299766 fatcat:yh26gfcjrjdp5oa62ufpvo2yd4