Restriction map and properties of Klebsiella oxytoca plasmid pACM1

pACM1 is a conjugative multiresistance (putative IncM) plasmid from Klebsie lla oxytoca. In order to make a structural and functional map, cloned fragm ents of pACM1 were systematically isolated from pUC19 libraries using DNA p robes from previously cloned fragments. All but approximately 3.6 kb of the plasmid were cloned and a consensus map is presented. Certain pACM1 fragme nts were "unclonable" (i.e., could not be detected among transformants) unl ess a 7-kb KpnI fragment was also present in the recombinant construct. Res triction 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 fra gment is probably within or includes part of the IncM tra (conjugation) ope ron. It is probable that pACM1 has loci functionally similar to the kil (le thal) and kor (kill override) loci in the tra operons of IncN or IncP plasm ids, pACM1 can be a valuable model for the study of IncM plasmids. (C) 1999 Academic Press.