A common precursor for the three subunits of L-glutamate oxidase encoded by gox gene from Streptomyces platensis NTU3304

A segment of DNA containing the L-glutamate oxidase (gm) gene from Streptom yces platensis NTU3304 was cloned. The entire nucleotide sequence of the pr otein-coding portion consisting of 2130 bp (710 codons, including AUG and U GA) of the cloned DNA fragment was determined. The gm gene contained only o ne open reading frame (ORF) which coded for a 78-kDa polypeptide, the precu rsor of active extracellular Cox. Mature Cox is composed of three subunits, designated as alpha, beta, and gamma, with molecular masses of 39, 19, and 16 kDa, respectively. Analyses of the N-terminal amino acid sequences of t he subunits revealed that the order of subunits in the precursor polypeptid e encoded by the ORF, from N-terminus to C-terminus, is alpha-gamma-beta. T he presence of the flavin adenine dinucleotide (FAD)binding motif place Cox as a member of the flavoenzyme family. Furthermore, a negative effect of g lucose on the biosynthesis of Gox was observed when it was used as carbon s ource.