Protein Plasticity and Protein-Lipid Interactions of the Beta-Barrel Assembly Machinery

Abstract

Elucidating protein plasticity and protein-lipid interactions is critical for a detailed understanding of the workings of membrane protein machines. We study the 88 kDa membrane-embedded protein BamA, which is the main component of the beta-barrel assembly machinery (BAM) that folds and inserts outer membrane proteins in gram-negative bacteria. Using a combination of electron microscopy (EM), limited proteolysis and NMR we characterized the fold and dynamics of different BamA constructs and the role of the lipid bilayer for protein structure.Our NMR studies provide atomic insight into protein dynamics and plasticity of the periplasmic POTRA domains and their interactions with the transmembrane domain. Moreover, we studied the influence of lipid type and the lipid-to-protein ratio on the atomic (solid-state NMR) and nm (EM) scale. Taken together, our results provide first clues into the interplay between protein - protein and protein -lipid interactions that may be critical for BAM-mediated substrate insertion into the outer membrane.View Large Image | View Hi-Res Image | Download PowerPoint Slide