Transformation-derived Neisseria gonorrhoeae plasmids with altered structure and function

Abstract

Plasmid deoxyribonucleic acid from Neisseria gonorrhoeae containing a 7.1kilobase (kb) (4.7-megadalton) penicillinase (Pcr) plasmid transformed homogenic gonococci to penicillinase production at a low frequency. About 25% of the penicillinase-producing gonococcal transformants contained Pc' plasmids which were either larger or smaller than the 7.1 kb donor plasmid; these Pcr 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 7.1kilobase Pcr plasmid and several of the smaller deleted plasmids was constructed. The most common size of altered Pc' plasmid was 5.1 kb (3.4 megadaltons). A Pc' 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 pcr plasmid could have arisen from a 7.1-kb Pcr plasmid by a transfonnation-associated deletion in nature.

Analysis of the plasmid content of three β-lactamase-producing Neisseria gonorrhoeae strains

“…This was confirmed by further analysis which showed that these plasmids contain a 1.6 kb fragment closely related to the /3-1actamase coding region of the Tn 3-like transposon Tn2301 [14,15]. The 7.4 kb plasmids reported here are probably identical to the 7.1 kb plasmids described by others [1,3].…”

“…Two types of R plasmids have been found in N. gonorrhoeae: one is 5.1 kilobase pairs (kb) long and the other 7.1 kb. They are closely related as judged by their high degree of homology [1,3]. In view of the medical significance of this resistance, it is of interest from an epidemiological point of view to analyse newly isolated gonococcal Amp r strains and to determine the genetic basis of their resistance.…”

Antimicrobial resistance

“…The resistance of gonococci to penicillin increased slowly over many years, but treatment failure could be prevented by suitably increased doses of penicillin. This resistance was chromosomal and non-enzymic; in 1976, however, plasmids determining the production of the TEM 1 ,-lactamase appeared in gonococci (12)(13)(14)(15), which then exhibited total resistance to penicillin. (For reviews of the development of resistance in gonococci, see references [16][17][18].…”

Beta-lactamase-specifying plasmids isolated from Neisseria gonorrhoeae have retained an intact right part of a Tn3-like transposon

“…A single restriction endonuclease BamHI cleavage site is present within the tnpR gene. The Ampr gonococcal plasmids contain this BamHI site, which is situated in the part homologous to Tn2 (23).…”