Transformation-derived Neisseria gonorrhoeae plasmids with altered structure and function

Abstract

Plasmid deoxyribonucleic acid from N. gonorrhoeae containing a 7.1-kilobase (kb) (4.7-megadalton) penicillinase (Pc(r)) plasmid transformed homogenic gonococci to penicillinase production at a low frequency. About 25% of the penicillinase-producing gonococcal transformants contained Pc(r) plasmids which were either larger or smaller than the 7.1 kb donor plasmid; these Pc(r) plasmids varied in size from 3.45 to 42 kb. Some of these altered plasmids differed from the donor plasmid in stability or in frequency of mobilization by a 36-kb (24-megadalton) conjugative plasmid. A restriction endonuclease cleavage map of the 7.1-kilobase Pc(r) plasmid and several of the smaller deleted plasmids was constructed. The most common size of altered Pc(r) plasmid was 5.1 kb (3.4 megadaltons). A Pc(r) plasmid isolated from a gonococcus in London, England, was identical with these 5.1-kb transformant plasmids in both size and restriction endonuclease cleavage profiles, suggesting that the 5.1-kb Pc(r) plasmid could have arisen from a 7.1-kb Pc(r) plasmid by a transformation-associated deletion in nature.