Identification of L-glutamine: 2-deoxy-scyllo-inosose-aminotransferase required for the biosynthesis of butirosin in Bacillus circulans

Using inverse PCR, two new genes (btrN and btrS) were identified upstream of the purative glycosyltransferase gene btrM in the butirosin-biosynthetic btr gene cluster of Bacillus circulans. The upstream gene btrS showed significant homology with stsC of Streptomyces griseus, which encodes L-glutamine : scyllo-inosose aminotransferase in the biosynthesis of streptomycin. The function of BtrS was further confirmed by heterologous expression in Escherichia coii and chemical identification of the conversion of 2-deoxy-scyllo-inosose into 2-deoxy-scyllo-inosamine. The identification of BtrS as L-glutamine: 2-deoxy-scyllo-inosose aminotransferase is the first report of the aminotransferase gene responsible for 2-deoxystreptamine biosynthesis.