THE THIOSTREPTON-RESISTANCE-ENCODING GENE IN STREPTOMYCES-LAURENTII IS LOCATED WITHIN A CLUSTER OF RIBOSOMAL-PROTEIN OPERONS

A common approach to identify and clone biosynthetic gene from an anti biotic-producing streptomycete is to clone the resistance gene for the antibiotic of interest and then use that gene to clone DNA that is li nked to it. As a first step toward cloning the genes responsible for t he biosynthesis of thiostrepton (Th) in Streptomyces laurentii (SI), t he Th resistance-encoding gene (tsnR) was cloned as a 1.5-kb BamHI-Pvu II fragment in Escherichia coli (Ec), and shown to confer Th resistanc e when introduced into S. lividans TK24. The tsnR-containing DNA fragm ent was used as a probe to isolate clones from cosmid libraries of DNA in the Ec cosmid vector SuperCos, and pOJ446 (an Ec/streptomycete) co smid vector, Sequence and genetic analysis of the DNA flanking the tsn R indicates that the Sl tsnR is not closely linked to biosynthetic gen es. Instead it is located within a cluster of ribosomal protein operon s.