Mapping a dynamic structural ensemble

Abstract

Structural Biology Many biological complexes are conformationally dynamic, which makes it difficult to determine the structures required to understand the mechanism. Marx et al. used an integrative approach to study the dynamic process of outer membrane protein (OMP) biogenesis that occurs in the periplasm of Gram-negative bacteria. Using a combination of photo–cross-linking, mass spectroscopy, solution scattering, and molecular modeling, they mapped interactions of a key chaperone, SurA, with unfolded OMPs (uOMPs) and determined an ensemble of models of the SurA:uOMP complex. The data show that a groove in SurA can bind several regions in uOMPs. Binding results in an expansion of the rest of the uOMP. Structural models indicate how SurA prevents OMP aggregation and how it may deliver uOMP to the β-barrel assembly machinery complex for insertion into the outer membrane. Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.2008175117 (2020).