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Publication Abstract from PubMed

Flavodoxins are small FMN-containing proteins that mediate a variety of electron transfer processes. The primary sequence of flavodoxin from Fusobacterium nucleatum, a pathogenic oral bacterium, is marked with a number of distinct features including a glycine to lysine (K13) substitution in the highly conserved phosphate binding loop (T/S-X-T-G-X-T), variation in the aromatic residues that sandwich the FMN cofactor, and a more even distribution of acidic and basic residues. The Eox/sq (oxidized/semiquinone; -43 mV) and Esq/hq (semiquinone/hydroquinone; -256 mV) are the highest recorded reduction potentials of known long-chain flavodoxins. These more electropositive values are a consequence of the apoprotein binding to the FMN hydroquinone anion with ~70-fold greater affinity compared to the oxidized form of the cofactor. Inspection of the FnFld crystal structure revealed the absence of a hydrogen bond between the protein and the oxidized FMN N5 atom, which likely accounts for the more electropositive Eox/sq . The more electropositive Esq/hq is likely attributed to only one negatively charged group positioned within 12 a of the FMN N1. We show that natural substitutions of highly conserved residues partially account for these more electropositive reduction potentials. This article is protected by copyright. All rights reserved.

Structural insight into the high reduction potentials observed for Fusobacterium nucleatum flavodoxin.,Mothersole RG, MacDonald M, Kolesnikov M, Murphy MEP, Wolthers KR Protein Sci. 2019 May 22. doi: 10.1002/pro.3661. PMID:31116469^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.