The exact nature of the sequence differences between the medically important family of gonococcal penicillinase-producing plasmids has been ascertained. The entire DNA sequence of the Asia-type plasmid, pJD4, demonstrated that it is 7426 bp and contains two direct repeats (DR30) that are implicated in the formation of deletion variant plasmids, such as the Africa-type plasmid. We have identified putative DnaA and IHF binding sites, various open reading frames that are thought to specify functional proteins, and some important DNA sequences involved with conjugative transfer of gonococcal beta-lactamase plasmids. The deletion in the Africa-type plasmid is 1827 bp and one of the DR30 repeats is also missing. The deletion in the Rio-type plasmid and several Toronto-type plasmids was determined to be 2273 bp and the sequence spanning the deletion was identical irrespective of geographic or temporal origin. The &Ncirc;imes-type plasmid is an Africa-type plasmid and also contains an IS5 insertion sequence. Since IS5 has not been identified in gonococcal isolates, we suggest that this sequence may have been inserted after the original gonococcal plasmid was transformed into Escherichia coli. The New Zealand plasmid is an Asia-type plasmid that contains an endogenous tandem duplication of 1883 bp and the direct DR2 is implicated in this duplication. The nature of the defined truncation of Tn2 present in the various plasmids is also discussed.
Copyright 2000 Academic Press.