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Nat Chem. 2019 Sep 16. doi: 10.1038/s41557-019-0329-3. [Epub ahead of print]

Temperature-jump solution X-ray scattering reveals distinct motions in a dynamic enzyme.

Author information

1
Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA.
2
Biophysics Graduate Program, University of California, San Francisco, San Francisco, CA, USA.
3
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
4
Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, San Francisco, CA, USA.
5
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA. anfinrud@nih.gov.
6
Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA. jfraser@fraserlab.com.

Abstract

Correlated motions of proteins are critical to function, but these features are difficult to resolve using traditional structure determination techniques. Time-resolved X-ray methods hold promise for addressing this challenge, but have relied on the exploitation of exotic protein photoactivity, and are therefore not generalizable. Temperature jumps, through thermal excitation of the solvent, have been utilized to study protein dynamics using spectroscopic techniques, but their implementation in X-ray scattering experiments has been limited. Here, we perform temperature-jump small- and wide-angle X-ray scattering measurements on a dynamic enzyme, cyclophilin A, demonstrating that these experiments are able to capture functional intramolecular protein dynamics on the microsecond timescale. We show that cyclophilin A displays rich dynamics following a temperature jump, and use the resulting time-resolved signal to assess the kinetics of conformational changes. Two relaxation processes are resolved: a fast process is related to surface loop motions, and a slower process is related to motions in the core of the protein that are critical for catalytic turnover.

PMID:
31527847
DOI:
10.1038/s41557-019-0329-3

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