Identification of Escherichia coli YgaF as an l -2-Hydroxyglutarate Oxidase

YgaF, a protein of previously unknown function inEscherichia coli , was shown to possess noncovalently bound flavin adenine dinucleotide and to exhibitl -2-hydroxyglutarate oxidase activity. The inability of anaerobic, reduced enzyme to reverse the reaction by reducing the product α-ketoglutaric acid is explained by the very high reduction potential (+19 mV) of the bound cofactor. The likely role of this enzyme in the cell is to recover α-ketoglutarate mistakenly reduced by other enzymes or formed during growth on propionate. On the basis of the identified function, we propose that this gene be renamedlhgO .