Expression and characterization of DrrA and DrrB proteins of Streptomyces peucetius in Escherichia coli: DrrA is an ATP binding protein.

Streptomyces peucetius, a microorganism that produces the anticancer drugs doxorubicin and daunorubicin, is itself resistant to the action of these drugs. The genes conferring resistance to doxorubicin and daunorubicin in S. peucetius have been sequenced (P. G. Guilfoile and R. Hutchinson, Proc. Natl. Acad. Sci. USA 88:8553-8557, 1991). Two open reading frames, drrA and drrB, were proposed to encode for an ABC (ATP-binding cassette) type of permease that carries out export of the antibiotics in an ATP-dependent manner. This article reports subcloning of the drrA and drrB genes into Escherichia coli expression vectors and characterization of their gene products. Upon induction from the lac promoter, a 36-kDa DrrA protein could be identified on Coomassie blue-stained gels. The DrrB protein was identified by use of a polyclonal antiserum generated against a synthetic peptide corresponding to a portion of the DrrB protein. Together, the DrrA and DrrB proteins conferred resistance to doxorubicin in E. coli. The DrrB protein was localized to the cell membrane. The DrrA protein bound ATP or GTP in a Mg2+-dependent fashion. ATP binding was enhanced on addition of doxorubicin or daunorubicin.