2cyu
From Proteopedia
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NMR structure of a downhill folding protein
Overview
Protein folding is an inherently complex process involving coordination of, the intricate networks of weak interactions that stabilize native, three-dimensional structures. In the conventional paradigm, simple protein, structures are assumed to fold in an all-or-none process that is, inaccessible to experiment. Existing experimental methods therefore probe, folding mechanisms indirectly. A widely used approach interprets changes, in protein stability and/or folding kinetics, induced by engineered, mutations, in terms of the structure of the native protein. In addition to, limitations in connecting energetics with structure, mutational methods, have significant experimental uncertainties and are unable to map complex, networks of interactions. In contrast, analytical theory predicts small, barriers to folding and the possibility of downhill folding. These, theoretical predictions have been confirmed experimentally in recent, years, including the observation of global downhill folding. However, a, key remaining question is whether downhill folding can indeed lead to the, high-resolution analysis of protein folding processes. Here we show, with, the use of nuclear magnetic resonance (NMR), that the downhill protein BBL, from Escherichia coli unfolds atom by atom starting from a defined, three-dimensional structure. Thermal unfolding data on 158 backbone and, side-chain protons out of a total of 204 provide a detailed view of the, structural events during folding. This view confirms the statistical, nature of folding, and exposes the interplay between hydrogen bonding, hydrophobic forces, backbone conformation and side-chain entropy. From the, data we also obtain a map of the interaction network in this protein, which reveals the source of folding cooperativity. Our approach can be, extended to other proteins with marginal barriers (less than 3RT), providing a new tool for the study of protein folding.
About this Structure
2CYU is a Single protein structure of sequence from [1]. Active as Dihydrolipoyllysine-residue succinyltransferase, with EC number 2.3.1.61 Full crystallographic information is available from OCA.
Reference
Atom-by-atom analysis of global downhill protein folding., Sadqi M, Fushman D, Munoz V, Nature. 2006 Jul 20;442(7100):317-21. Epub 2006 Jun 14. PMID:16799571
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