One β Hairpin after the Other: Exploring Mechanical Unfolding Pathways of the Transmembrane β-Barrel Protein OmpG

摘要

Single-molecule force spectroscopy (SMFS) is a unique approach to study the mechanical unfolding of proteins Such forced unfolding experiments yield insight into how interactions stabilize a protein and guide its unfolding pathways. Previous SMFS work has probed the mechanical stability of water-soluble proteins composed of α helices and β strands. A prominent example of unfolding of a β-barrel structure is that of the green fluorescent protein (GFP), the stability of which plays a major role for its application as a marker in modern fluorescence microscopy. In contrast to the variety of water-soluble proteins characterized, only α-helical membrane proteins have been probed by SMFS. It was found that α-helical membrane proteins unfold via many intermediates, which is different to the mostly two-state unfolding process of water-soluble proteins.