Genetic analysis of the gentamicin resistance region of pPH1JI and incorporation into a wide host range cloning vehicle.

A region of the IncP plasmid pPH1JI encoding resistance to gentamicin, spectinomycin, and streptomycin was characterized by subcloning, deletion, and insertion mutagenesis. Approximate locations of these resistance determinants were established. A 1.6-kb HindIII-SphI segment of this region expresses gentamicin resistance (Gmr) in Escherichia coli when inserted into various plasmid vectors; this DNA segment encodes a polypeptide of 17.5 kDa. Incorporation of this fragment into an IncP cloning vehicle produced a Gmr wide host range vector, pRAR209, which confers levels of Gmr comparable to those expressed by pPH1JI in E. coli, Agrobacterium tumefaciens, and Rhizobium meliloti.