Partial streptomycin biosynthesis cluster for genes flanking strA. (The figure is reproduced with permission from W. Piepersberg [11a].) The genes analyzed in this study are shaded. The bar represents distance in kilobases. , aminotransferase, biosynthesis; , presumed epimerase, biosynthesis; , amidinotransferase, biosynthesis; , phosphotransferase, streptomycin resistance; , regulation.