A mammalian vector carrying the bleomycin N-acetyltransferase gene from bleomycin-producing Streptomyces verticillus as a selective marker.

A gene, blmB, encodes a bleomycin (Bm) N-acetyltransferase, designated BAT, from Bm-producing Streptomyces verticillus and confers resistance to Bm in Streptomyces and Escherichia coli. COS-1 cells transfected with a plasmid designated pEF-BOS/blmB, in which blmB is under the control of a strong promoter from the human polypeptide chain elongation factor 1alpha, transiently produced BAT. Immuno-cytochemical analysis using an anti-BAT monoclonal antibody revealed that BAT was localized in the nucleus of the blmB-carrying COS-1 cells. NIH/3T3 cells, transfected with pEF-BOS/blmB, stably expressed BAT at least for one month. The stable transformants of blmB showed specific resistance to the Bm family of antibiotics, suggesting that blmB has potential as a selective marker in gene transfer studies with mammalian cells.