Membrane Proteins Have Distinct Fast Internal Motion and Residual Conformational Entropy.

ABSTRACT: The internal motions of integral membrane proteins have largely eluded comprehensive experimental characterization. Here the fast side-chain dynamics of the ?-helical sensory rhodopsin?II and the ?-barrel outer membrane protein?W have been investigated in lipid bilayers and detergent micelles by solution NMR relaxation techniques. Despite their differing topologies, both proteins have a similar distribution of methyl-bearing side-chain motion that is largely independent of membrane mimetic. The methyl-bearing side chains of both proteins are, on average, more dynamic in the ps-ns timescale than any soluble protein characterized to date. Accordingly, both proteins retain an extraordinary residual conformational entropy in the folded state, which provides a counterbalance to the absence of the hydrophobic effect. Furthermore, the high conformational entropy could greatly influence the thermodynamics underlying membrane-protein functions, including ligand binding, allostery, and signaling.

SUBMITTER: O'Brien ES 

PROVIDER: S-EPMC7318686 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature