Abstract
The flavodoxin of Rhodopseudomonas palustris CGA009 (Rp9Fld) supplies highly reducing equivalents to crucial en- zymes such as hydrogenase, especially when the organism is iron-restricted. By acquiring those electrons from photodriven electron flow via the bifurcating electron transfer flavoprotein, Rp9Fld provides solar power to vital metabolic processes. To understand Rp9Fld’s ability to work with diverse partners, we solved its crystal structure. We observed the canonical fla- vodoxin (Fld) fold and features common to other long-chain Flds but not all the surface loops thought to recognize part- ner proteins. Moreover, some of the loops display alternative structures and dynamics. To advance studies of protein– protein associations and conformational consequences, we assigned the 19 F NMR signals of all five tyrosines (Tyrs). Our electrochemical measurements show that incorporation of 3- 19 F-Tyr in place of Tyr has only a modest effect on Rp9Fld’s redox properties even though Tyrs flank the flavin on both sides. Meanwhile, the 19 F probes demonstrate the expected paramagnetic effect, with signals from nearby Tyrs becoming broadened beyond detection when the flavin semiquinone is formed. However, the temperature dependencies of chemical shifts and linewidths reveal dynamics affecting loops close to the flavin and regions that bind to partners in a variety of systems. These coincide with patterns of amino acid type conservation but not retention of specific residues, arguing against detailed specificity with respect to partners. We pro- pose that the loops surrounding the flavin adopt altered con- formations upon binding to partners and may even participate actively in electron transfer.
Document Type
Article
Publication Date
2024
Digital Object Identifier (DOI)
https://doi.org/10.1016/j.jbc.2024.107122
Funding Information
This work was supported by NSF grant number CHE-CMI 2154206 to S. M. DOE DE- SC0021283 and KY-EPSCoR PON2 635 2000003148 funding to A. F. M. NSF CHE 2108134 supported contributions of D. D. to sample production.
Repository Citation
Khan, Sharique; Ansari, Ahmadullah; Brachi, Monica; Das, Debarati; El Housseini, Wassim; Minteer, Shelley; and Miller, Anne-Francis, "Structure, dynamics, and redox reactivity of an all-purpose flavodoxin" (2024). Markey Cancer Center Faculty Publications. 206.
https://uknowledge.uky.edu/markey_facpub/206
Notes/Citation Information
© 2024 THE AUTHORS. Published by Elsevier Inc on behalf of American Society for Biochemistry and Molecular Biology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).