DNA restriction and modification systems in Neisseria gonorrhoeae

Davies, John K.

doi:10.1128/cmr.2.suppl.s78

Cited by 15 publications

(12 citation statements)

References 25 publications

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“…Alternatively, N. gonorrhoeae may exclude foreign DNA more efficiently because of its plethora of restriction barriers. Korch et al (12,13) as well as Davies (3) have independently noted that any gonococcal strain potentially has seven type-TI restriction-modification systems. We initially attempted to determine the differences in restrictionmodification systems between the gonococcal strains F62 and PGH 3-2 as well as the commensal N. flava by digesting chromosomal DNA from these strains with isoschizomers of the seven characterized gonococcal restriction enzymes.…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, of the seven characterized or inferred gonococcal restriction enzymes, three have internal 5'-CG-3' dinucleotides in their recognition sequences (3). Methylation of the cytosine in a 5'-CG-3' pair would protect against the gonococcal restriction enzymes R.NgoI (R.HaeII), R.NgoIII (R.SacII), and R.NgoIV (R.NaeI).…”

Section: Resultsmentioning

confidence: 99%

“…We hypothesized that the barrier to mobilization of RSF1010 into strain F62-RN was at the level of restriction in the new host. The gonococcus has a very complex restriction-modification system (3,12,13,30 is the recipient but has no effect on the frequency when F62-RN is the recipient. Thus, methylation of NgoII (HaeIII) sites is essential for increased conjugal transfer in strain PGH 3-2R but not in strain F62-RN.…”

Section: Resultsmentioning

confidence: 99%

“…Some mating experiments were performed in the presence of DNase (100 ,ug/ml) in order to prevent the acquisition of plasmids by transformation. The (3,000 Ci/mmol; Amersham) by following the instructions of the random-priming kit (Boehringer, Mannheim, Germany).…”

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High-frequency mobilization of broad-host-range plasmids into Neisseria gonorrhoeae requires methylation in the donor

Butler

Gotschlich

1991

J Bacteriol

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Antibiotic resistance in Neisseria gonorrhoeae has been associated with the acquisition of R plasmids from heterologous organisms. The broad-host-range plasmids of incompatibility groups P (IncP) and Q (IncQ) have played a role in this genetic exchange in nature. We have utilized derivatives of RSF1010 (IncQ) and RP1 (IncP) to demonstrate that the plethora of restriction barriers associated with the gonococci markedly reduces mobilization of plasmids from Escherichia coli into strains F62 and PGH 3-2. Partially purified restriction endonucleases from these gonococcal strains can digest RSF1010 in vitro. Protection of RSF1010-km from digestion by gonococcal enzymes purified from strain F62 is observed when the plasmid is isolated from E. coli containing a coresident plasmid, pCAL7. Plasmid pCAL7 produces a 5 _MECG-3' cytosine methylase (M.SssI). The M.SssI methylase only partially protects RSF1010-km from digestion by restriction enzymes from strain PGH 3-2. Total protection of RSF1010-km from PGH 3-2 restriction requires both pCAL7 and a second coresident plasmid, pFnuDI, which produces a 5'-GG'CC-3' cytosine methylase. When both F62 and PGH 3-2 are utilized as recipients in heterospecific matings with E. coli, mobilization of RSF1010 from strains containing the appropriate methylases into the gonococci occurs at frequencies 4 orders of magnitude higher than from strains without the methylases. Thus, protection of RSF1010 from gonococcal restriction enzymes in vitro correlates with an increase in the conjugal frequency. These data indicate that restriction is a major barrier against efficient conjugal transfer between N. gonorrhoeae and heterologous hosts.In nature, conjugation appears to play an important role in the mobilization of antibiotic resistance plasmids into various species of the genus Neisseria. Resistance plasmids can be transferred, for example, from enteric bacteria to Neisseria gonorrhoeae, as has been hypothesized by Roberts and Falkow (22). Likewise, other investigators have demonstrated that the broad-host-range incompatibility group P (IncP) plasmid pUB307 can mobilize pLES2 from Escherichia coli to N. gonorrhoeae (18). Thus, IncP elements may contribute to the establishment of resistance plasmids in Neisseria spp., although IncP elements have not been found in Neisseria organisms. It is assumed that this group of plasmids cannot be maintained in N. gonorrhoeae because of plasmid replication deficiencies (18). In addition to the 3-lactamase plasmids, plasmids having homology to the broad-host-range incompatibility group Q (IncQ) plasmids, namely, RSF1010, have been found in a variety of commensal Neisseria species and in Neisseria meningitidis (5,19,23,24). These RSF1010-like plasmids are the first multiresistant plasmid group found in Neisseria spp., having resistance not only to sulfonamide and streptomycin but also to ampicillin (23). The possibility exists for dissemination of these plasmids into N. gonorrhoeae.Naturally occurring IncP elements (as illustrated by RK2, RP1, and R68 [1]...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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High-frequency mobilization of broad-host-range plasmids into Neisseria gonorrhoeae requires methylation in the donor

Butler

Gotschlich

1991

J Bacteriol

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“…gonorrhoeae produces at least five different restriction enzymes and eleven different methylases (13,25). A screening of 30 gonococcal isolates revealed that all but one had methylase activity, and about half produced detectable restriction enzymes (41).…”

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confidence: 99%