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Title: Probing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering

Abstract

Direct tracking of protein structural dynamics during folding-unfolding processes is important for understanding the roles of hierarchic structural factors in the formation of functional proteins. Using cytochrome c (cyt c) as a platform, we investigated its structural dynamics during folding processes triggered by local environmental changes (i.e., pH or heme iron center oxidation/spin/ligation states) with time-resolved X-ray solution scattering measurements. Starting from partially unfolded cyt c, a sudden pH drop initiated by light excitation of a photoacid caused a structural contraction in microseconds, followed by active site restructuring and unfolding in milliseconds. In contrast, the reduction of iron in the heme via photoinduced electron transfer did not affect conformational stability at short timescales (<1 ms), despite active site coordination geometry changes. These results demonstrate how different environmental perturbations can change the nature of interaction between the active site and protein conformation, even within the same metalloprotein, which will subsequently affect the folding structural dynamics.

Authors:
 [1];  [1];  [1];  [1];  [2];  [3];  [3]; ORCiD logo [4]
  1. Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
  2. Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
  3. Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
  4. Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1473619
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 122; Journal Issue: 20; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English

Citation Formats

Rimmerman, Dolev, Leshchev, Denis, Hsu, Darren J., Hong, Jiyun, Abraham, Baxter, Henning, Robert, Kosheleva, Irina, and Chen, Lin X. Probing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering. United States: N. p., 2018. Web. doi:10.1021/acs.jpcb.8b03354.
Rimmerman, Dolev, Leshchev, Denis, Hsu, Darren J., Hong, Jiyun, Abraham, Baxter, Henning, Robert, Kosheleva, Irina, & Chen, Lin X. Probing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering. United States. doi:10.1021/acs.jpcb.8b03354.
Rimmerman, Dolev, Leshchev, Denis, Hsu, Darren J., Hong, Jiyun, Abraham, Baxter, Henning, Robert, Kosheleva, Irina, and Chen, Lin X. Mon . "Probing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering". United States. doi:10.1021/acs.jpcb.8b03354.
@article{osti_1473619,
title = {Probing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering},
author = {Rimmerman, Dolev and Leshchev, Denis and Hsu, Darren J. and Hong, Jiyun and Abraham, Baxter and Henning, Robert and Kosheleva, Irina and Chen, Lin X.},
abstractNote = {Direct tracking of protein structural dynamics during folding-unfolding processes is important for understanding the roles of hierarchic structural factors in the formation of functional proteins. Using cytochrome c (cyt c) as a platform, we investigated its structural dynamics during folding processes triggered by local environmental changes (i.e., pH or heme iron center oxidation/spin/ligation states) with time-resolved X-ray solution scattering measurements. Starting from partially unfolded cyt c, a sudden pH drop initiated by light excitation of a photoacid caused a structural contraction in microseconds, followed by active site restructuring and unfolding in milliseconds. In contrast, the reduction of iron in the heme via photoinduced electron transfer did not affect conformational stability at short timescales (<1 ms), despite active site coordination geometry changes. These results demonstrate how different environmental perturbations can change the nature of interaction between the active site and protein conformation, even within the same metalloprotein, which will subsequently affect the folding structural dynamics.},
doi = {10.1021/acs.jpcb.8b03354},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
issn = {1520-6106},
number = 20,
volume = 122,
place = {United States},
year = {2018},
month = {4}
}