Restriction map and properties of Klebsiella oxytoca plasmid pACM1.

pACM1 is a conjugative multiresistance (putative IncM) plasmid from Klebsiella oxytoca. In order to make a structural and functional map, cloned fragments of pACM1 were systematically isolated from pUC19 libraries using DNA probes from previously cloned fragments. All but approximately 3.6 kb of the plasmid were cloned and a consensus map is presented. Certain pACM1 fragments were "unclonable" (i.e., could not be detected among transformants) unless a 7-kb KpnI fragment was also present in the recombinant construct. Restriction sites found in a portion of the 7-kb KpnI fragment resemble those of the iml determinant region of IncM plasmid R446; therefore, the 7-kb fragment is probably within or includes part of the IncM tra (conjugation) operon. It is probable that pACM1 has loci functionally similar to the kil (lethal) and kor (kill override) loci in the tra operons of IncN or IncP plasmids. pACM1 can be a valuable model for the study of IncM plasmids.