Studies of the membrane-bound flavocytochrome MsrQ flavin mononucleotide (FMN)-binding site reveal an unexpected ubiquinone cofactor.

ABSTRACT: The methionine sulfoxide reductase PQ system (MsrPQ) is a newly identified type of bacterial methionine sulfoxide reductase (Msr) involved in the repair of periplasmic methionine residues that have been oxidized by hypochlorous acid. MsrP, which carries out the Msr activity, is a molybdoenzyme located in the periplasm, whereas MsrQ, an integral membrane-bound flavohemoprotein, specifically transfers electrons to MsrP to drive catalysis. MsrQ belongs to an important superfamily of heme-containing membrane-bound proteins, which includes the eukaryotic NADPH oxidases (NOX) and six-transmembrane epithelial antigen of the prostate (STEAP) ferric reductases. Like STEAP, and in addition to a b-type heme, MsrQ contains a flavin cofactor [flavin mononucleotide (FMN)], which mediates electron transf

SUBMITTER: Carpentier P 

PROVIDER: S-EPMC12525009 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature