Expression of the kanamycin resistance gene in a kanamycin-producing strain of Streptomyces kanamyceticus.

The previously cloned kanamycin resistance gene (kmr) from Streptomyces kanamyceticus ISP5500 was shown to modify the 30S ribosomal subunit in a subunit exchange experiment. The kmr gene, which was normally repressed in S. kanamyceticus, appeared to be induced under growth conditions which activated kanamycin biosynthesis. S1 mapping analysis revealed that the expression of the kmr gene was regulated at the transcriptional level. Acetylation of kanamycin is another resistance mechanism in the kanamycin producer. However, unlike kmr-mediated resistance, the enzyme which catalyzed acetylation was not regulated coordinately with kanamycin biosynthesis.