Plasmid deoxyribonucleic acid in clinical isolates of Neisseria gonorrhoeae

A conjugation system initially discovered in fl-lactamase-producing gonococci mobilized small non-selftransmissible R plasmids encoding ,8-lactamase (penicillinase) production into other gonococci, Neisseria, and Escherichia coli. This conjugation system was mediated by a separate selftransmissible plasmid of 23.9 x 106 daltons, pFA2. Conjugative plasmids capable of mobilizing R plasmids were also found in nearly 8% of the non-penicillinase-producing gonococci. These were similar to pFA2 in size, buoyant density, and restriction endonuclease digest patterns but were less efficient than pFA2 in mobilization of the penicillinase plasmid pFA3. The presence of conjugative plasmids in gonococci isolated before the appearance of penicillinase-producing strains indicates that a conjugation system for plasmid transfer predated the appearance of R plasmids in gonococci.Recently, strains of Neisseria gonorrhoeae with plasmid-mediated ,f-lactamase (penicillin-278 on July 16, 2020 by guest

Section: Resultssupporting

confidence: 54%

Conjugative plasmids in Neisseria gonorrhoeae

Sox¹,

Mohammed²,

Blackman³

et al. 1978

“…Our findings with the Haemophilus R plasmids, together with previous observations (16, 24,27,32) that most N. gonorrhoeae strains carry indigenous plasmids, led us to speculate (18) that plasmid-mediated penicillin resistance in the gonococci was a distinct, if not inevitable, possibility. This speculation became a reality in early 1976 (2,5,28,29), when /3lactamase-producing strains ofN.…”

supporting

confidence: 72%

Molecular characterization of two beta-lactamase-specifying plasmids isolated from Neisseria gonorrhoeae

Roberts¹,

Elwell²,

Falkow³

1977

134

The molecular nature of two distinct gonococcal R plasmids, 4.4 X 10(6) and 3.2 X 10(6) daltons, encoding beta-lactamase activity were examined. Both plasmids contained about 40% of the transposable ampicillin resistance sequence Tn2. Deoxyribonucleic acid-deoxyribonucleic acid polynucleotide sequence studies have shown that the two gonococcal plasmids share about 70% of their sequences and are closely related to RSF0885, a 4.1 X 10(6)-dalton plasmid found in a beta-lactamase-producing strain of Haemophilus influenzae. All three of these R plasmids possess a guanine-plus-cytosine content of 0.40 to 0.41 mol fraction and are present as multicopy gene pools in their bacterial hosts.

“…We have analyzed these strains for their plasmid content. All three of them carry the common cryptic 4.2-kb plasmid (14), two contain a large 38-kb plasmid (24), and all three carry a third plasmid species of 7.4 kb. The Ampr phenotype is due to this 7.4-kb plasmid.…”

Section: Identification Of the Plasmid Responsible For Thementioning

confidence: 99%

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

Fayet¹,

Froment²,

Piffaretti³

1982

In three beta-lactamase-producing strains of Neisseria gonorrhoeae, ampicillin resistance is due to the presence of a 7.4-kilobase plasmid. Heteroduplex analysis has shown that the R plasmid contains a 1.6-kilobase segment homologous to the right part (the region coding for the beta-lactamase) of the Tn3-like transposon Tn2301 the 1.6-kilobase DNA segment is not transposable, but it can give rise to a functional transposon, when linked to the left part of TN2301. This provides strong evidence that the R plasmids of N. gonorrhoeae are deletion derivatives of a plasmid that contained an entire TN3-like transposon.