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Identifying structural and dynamic changes during the Biliverdin Reductase B catalytic cycle

Cornell Affiliated Author(s)

Author

E. Lee
M.J. McLeod
J.S. Redzic
B. Marcolin
R.E. Thorne
P. Agarwal
E.Z. Eisenmesser

Abstract

Biliverdin Reductase B (BLVRB) is an NADPH-dependent reductase that catalyzes the reduction of multiple substrates and is therefore considered a critical cellular redox regulator. In this study, we sought to address whether both structural and dynamics changes occur between different intermediates of the catalytic cycle and whether these were relegated to just the active site or the entirety of the enzyme. Through X-ray crystallography, we determined the apo BLVRB structure for the first time, revealing subtle global changes compared to the holo structure and identifying the loss of a critical hydrogen bond that “clamps” the R78-loop over the coenzyme. Amide and Cα chemical shift perturbations were used to identify environmental and secondary structural changes between intermediates, with more distant global changes observed upon coenzyme binding compared to substrate interactions. NMR relaxation rate measurements provided insights into the dynamic behavior of BLVRB during the catalytic cycle. Specifically, the inherently dynamic R78-loop that becomes ordered upon coenzyme binding persists through the catalytic cycle while similar regions experience dynamic exchange. However, the dynamic exchange processes were found to differ through the catalytic cycle with several groups of residues exhibiting similar dynamic responses. Finally, both local and distal structural and dynamic changes occur within BLVRB that are dependent solely on the oxidative state of the coenzyme. Thus, through a comprehensive analysis here, this study revealed structural and dynamic alterations in BLVRB through its catalytic cycle that are not simply relegated to the active site, but instead, are allosterically coupled throughout the enzyme. Copyright © 2023 Lee, McLeod, Redzic, Marcolin, Thorne, Agarwal and Eisenmesser.

Date Published

Journal

Frontiers in Molecular Biosciences

Volume

10

Type of Article

Article

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85169086103&doi=10.3389%2ffmolb.2023.1244587&partnerID=40&md5=a8eb705afd4e7d85b5b2a0f84984e887

DOI

10.3389/fmolb.2023.1244587

Research Area

Group (Lab)

Robert Thorne Group

Funding Source

1807326
R01GM139892
DMR-1829070
GM-124166-01A1

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