Monitoring Backbone Hydrogen‐Bond Formation in β‐Barrel Membrane Protein Folding. (9th April 2016) - Raschle, Thomas
Abstract: β‐barrel membrane proteins are key components of the outer membrane of bacteria, mitochondria and chloroplasts. Their three‐dimensional structure is defined by a network of backbone hydrogen bonds between adjacent β‐strands. Here, we employ hydrogen–deuterium (H/D) exchange in combination with NMR spectroscopy and mass spectrometry to monitor backbone hydrogen bond formation during folding of the outer membrane protein X (OmpX) from E. coli in detergent micelles. Residue‐specific kinetics of interstrand hydrogen‐bond formation were found to be uniform in the entire β‐barrel and synchronized to formation of the tertiary structure. OmpX folding thus propagates via a long‐lived conformational ensemble state in which all backbone amide protons exchange with the solvent and engage in hydrogen bonds only transiently. Stable formation of the entire OmpX hydrogen bond network occurs downhill of the rate‐limiting transition state and thus appears cooperative on the overall folding time scale. Abstract : Die Faltungsmechanismen von β‐Barrel‐Membranproteinen sind auf atomarer Ebene noch nicht verstanden. H/D‐Austausch wurde verwendet, um die Wasserstoffbrückenbildung beim Falten des β‐Barrel‐Membranproteins OmpX in atomarer Auflösung zu verfolgen. Die Kinetiken der Wasserstoffbrückenbildung sind im gesamten Barrel einheitlich, was für eine kooperative Bildung des Wasserstoffbrückennetzwerks spricht.