远端霉素合成基因簇下游基因dst27，dst28，dst29的初步探究

istamycin (DST) is a well-known DNA minor groove binder which is produced by Strptomyces netropsis. It has antivirus effect and antitumor potency. Cluster 1 (28 kb) and 2 (7 kb)have recently been identified to coordinately produce the DST. Here we report a gene cassette, which is linked to the smaller dst gene cluster could effect the production of DST. This cassette consists of three uncharacterized genes，namely dst27, dst28, dst29, In silico analyze shows these three genes are all associated with the DNA replication/repair. Knockout of the cassette led to decrease in DST production, while heterologous expression leds to a similar decrease in DST production. Homologs of these three genes also exist in genomes of other actinomyces that produce DNA-binding antibiotics.This phenomenon implies that dst27, dst28, dst29 may represent a common resistance mechanism in many DNA binding metabolites producers.