Evidence for close side-chain packing in an early protein folding intermediate previously assumed to be a molten globule
| Autor: | Katelyn Connell, Laura E. Rosen, Susan Marqusee |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Protein Structure
Secondary Protein Folding Magnetic Resonance Spectroscopy DNA Mutational Analysis Ribonuclease H Anilino Naphthalenesulfonates Fluorescence Protein Structure Secondary Enzyme Stability Native state Side chain Escherichia coli Urea Folding funnel Amino Acids Protein secondary structure Multidisciplinary Chemistry Circular Dichroism Biological Sciences Protein tertiary structure Molten globule Protein Structure Tertiary NMR spectra database Crystallography Kinetics Mutation Protein folding Hydrophobic and Hydrophilic Interactions Tertiary |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America, vol 111, iss 41 |
| Popis: | The molten globule, a conformational ensemble with significant secondary structure but only loosely packed tertiary structure, has been suggested to be a ubiquitous intermediate in protein folding. However, it is difficult to assess the tertiary packing of transiently populated species to evaluate this hypothesis. Escherichia coli RNase H is known to populate an intermediate before the rate-limiting barrier to folding that has long been thought to be a molten globule. We investigated this hypothesis by making mimics of the intermediate that are the ground-state conformation at equilibrium, using two approaches: a truncation to generate a fragment mimic of the intermediate, and selective destabilization of the native state using point mutations. Spectroscopic characterization and the response of the mimics to further mutation are consistent with studies on the transient kinetic intermediate, indicating that they model the early intermediate. Both mimics fold cooperatively and exhibit NMR spectra indicative of a closely packed conformation, in contrast to the hypothesis of molten tertiary packing. This result is important for understanding the nature of the subsequent rate-limiting barrier to folding and has implications for the assumption that many other proteins populate molten globule folding intermediates. |
| Databáze: | OpenAIRE |
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