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  • Alternative pyrimidine biosynthesis protein ApbE is a flavin transferase catalyzing covalent attachment of FMN to a threonine residue in bacterial flavoproteins.

Alternative pyrimidine biosynthesis protein ApbE is a flavin transferase catalyzing covalent attachment of FMN to a threonine residue in bacterial flavoproteins.

The Journal of biological chemistry (2013-04-06)
Yulia V Bertsova, Maria S Fadeeva, Vitaly A Kostyrko, Marina V Serebryakova, Alexander A Baykov, Alexander V Bogachev
ABSTRACT

Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) contains two flavin residues as redox-active prosthetic groups attached by a phosphoester bond to threonine residues in subunits NqrB and NqrC. We demonstrate here that flavinylation of truncated Vibrio harveyi NqrC at Thr-229 in Escherichia coli cells requires the presence of a co-expressed Vibrio apbE gene. The apbE genes cluster with genes for Na(+)-NQR and other FMN-binding flavoproteins in bacterial genomes and encode proteins with previously unknown function. Experiments with isolated NqrC and ApbE proteins confirmed that ApbE is the only protein factor required for NqrC flavinylation and also indicated that the reaction is Mg(2+)-dependent and proceeds with FAD but not FMN. Inactivation of the apbE gene in Klebsiella pneumoniae, wherein the nqr operon and apbE are well separated in the chromosome, resulted in a complete loss of the quinone reductase activity of Na(+)-NQR, consistent with its dependence on covalently bound flavin. Our data thus identify ApbE as a novel modifying enzyme, flavin transferase.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Riboflavin 5′-monophosphate sodium salt hydrate, 73-79% (fluorimetric)
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Riboflavin 5′-monophosphate sodium salt hydrate, suitable for electrophoresis, suitable for acrylamide photopolymerization, ≥70%, powder
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Riboflavin 5′-monophosphate sodium salt hydrate, synthetic, ≥70% (HPLC)
Riboflavin sodium phosphate, European Pharmacopoeia (EP) Reference Standard
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Riboflavin Sodium Phosphate Hydrate, tested according to Ph. Eur.