Properties of R Plasmids Determining Gentamicin Resistance by Acetylation in
            <i>Pseudomonas aeruginosa</i>

Plasmid Rms149, the archetype of Pseudomonas plasmid incompatibility group IncP-6, was identified in Pseudomonas aeruginosa as an agent conferring resistance to streptomycin, sulfanilamide, gentamicin, and carbenicillin in 1975. It has been classed as a broad-host-range plasmid due to its ability to replicate in both Escherichia coli (where it is designated IncG) and Pseudomonas species, although both species are ␥-proteobacteria. To provide reference information on this Inc group, we have determined the complete sequence of Rms149 and found that, although the genome comprises 57,121 bp, it is essentially a small mobilizable plasmid carrying multiple mobile elements, which make up 79% (>45 kb) of its genome. A replicon has been identified which encodes a single polypeptide with moderate identity to other replication proteins. The region encoding this protein can replicate in Pseudomonas putida and E. coli. This sequence is directly downstream of a putative partitioning region highly similar to that of pRA2. A functional IncQ-type mobilization region is also present. Thus, the backbone appears to be a novel combination of modules already identified in other plasmid systems. Analysis of the segments that fall outside this core of stable inheritance and transfer functions show that this plasmid has been subject to multiple insertion events and that the plasmid appears to carry a considerable load of DNA that no longer should be phenotypically advantageous. The plasmid therefore functions not just as a vehicle for spread of selective traits but also as a store for DNA that is not currently under selection.The key features of a plasmid are the ability to replicate autonomously and to be maintained in a cell lineage without a high rate of segregational loss. An optional but frequently encountered property is the ability to transfer or to be mobilized from one bacterium to another. From these properties it follows that genes that become associated with a plasmid may spread rapidly from one genetic background to another. Some plasmids appear to consist of nothing more than functions that confer the above core abilities, and these have been termed cryptic plasmids.To succeed as such a selfish element, a plasmid must be stable and confer minimal burden on its host, or at least overcome competitive losses by horizontal transfer (42). Conversely, a plasmid carrying genes that promote the growth of its host, relative to competitor bacteria, will benefit by increased propagation. However, since maintenance of a plasmid is generally found to place a metabolic or phenotypic load on the cell, universally useful genes will be selectively reacquired by the chromosome over evolutionary time. Therefore, successful plasmids typically carry payload genes, favorable in some environments but not others (12), or genes with a transient plasmid association that are spreading through a microbial community. In passing through different strains or species, plasmids are exposed to different genetic contexts and provide the opportunity for comb...

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“…For E. coli K-12 the strains used were as follows: DH5␣ [ (23). Plasmids used or constructed during this work are described in Table 1.…”

Section: Methodsmentioning

confidence: 99%

The IncP-6 Plasmid Rms149 Consists of a Small Mobilizable Backbone with Multiple Large Insertions

et al. 2005

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“…Since cells carrying pMGz fail to plate phage E79 (Jacoby, 1974) it was necessary to isolate a mutant of the R factor which does not affect the phage plating efficiency of the bacterial host strain. The derived R factor PPLI is able to transfer the drug-resistance properties and confer protection against U.V.…”

Section: R E S U L T Smentioning

confidence: 99%

“…The P. aeruginosa R factor pMG2 (Jacoby, 1974) confers resistance to gentamicin, streptomycin and sulphonamides and is a member of the compatibility group P-2. This plasmid is transmissible to various strains of Pseudomonas but not to Escherichia coli or other enteric bacteria.…”

Section: Introductionmentioning

confidence: 99%

Plasmid Modification of Radiation and Chemical-mutagen Sensitivity in Pseudomonas aeruginosa

Lehrbach

Kung

Lee

et al. 1977

Journal of General Microbiology

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The R factor pMG2 protects Pseudomonas aeruginosa against the lethal effects of ultraviolet (u.v.) and gamma irradiation, and methyl methanesulphonate and N-methyl-N'-nitro-N-nitrosoguanidine treatment. Enhanced survival occurs in strains of uvr+ rec+ (wild-type) genotype and a variety of uvr rec+ type mutants. No protection occurs in a red-type mutant. The plasmid also enhances u.v.-induced mutagenesis. These effects appear to be due to host-cell controlled plasmid-determined DNA repair function(s). Studies on P. aeruginosa strains deficient in DNA polymerase I (polA) suggest that a plasmid-determined repair resynthesis function may be responsible for increased u.v.-survival and enhanced u.v.-mutability in pMG2-containing bacteria.

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“…A possible complication is that the presence of an R factor may change typing characteristics of the host. Jacoby has reported an inhibition of propagation of som3 phage, and an inhibition of production of standard pyocins, by R factor pMGl in P. aeruginosa PU21 (9). The relationships of the R factors described here to the expression of host bacteriophage and pyocin typing remain to be examined.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, descriptions have appeared of R factors in this organism, including reports of factors determining resistance to one or the other of these antibiotics (3,4,8,9,11,12,14,15,17). These findings prompted our search for transmissible drug resistance among clinical strains of P. aeruginosa identified in the University of Cin--cinnati Medical Center.…”

mentioning

confidence: 99%

Pseudomonas aeruginosa R Factors Determining Gentamicin Plus Carbenicillin Resistance from Patients with Urinary Tract Colonizations

Korfhagen

Loper

Ferrel

1975

Antimicrob Agents Chemother

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R factors determining multiple resistance including both gentamicin and carbenicillin have been identified in high incidence among hospital isolates of Pseudomonas aeruginosa. The factors are readily transmitted to other P. aeruginosa but not to Escherichia coli strains K-12 or C, or to Proteus mirabilis. R factor-containing isolates are predominantly immunotype 7 isolated from urinary sources.Pseudomonas aeruginosa, although resistant to many antibiotics, has been generally susceptible to gentamicin and carbenicillin. Recently, descriptions have appeared of R factors in this organism, including reports of factors determining resistance to one or the other of these antibiotics (3,4,8,9,11,12,14,15, 17 with L-amino acids at 20 ,ug/ml as required. Antibiotics were used in selection plates at the following concentrations (;g/ml): gentamicin, 1 to 20; carbenicillin, 50, 500, or 750; streptomycin, 100; tetracycline, 100; kanamycin, 50; and rifampin, 100.Antibiotic resistance. Antibiotic disk susceptibilities were determined by the Bauer-Kirby method (2) with Mueller-Hinton agar (Difco). For determination of minimal inhibitory concentrations, single drops with 101 organisms from ovemight culture were spotted on similar agar media containing serial twofold supplements of antibiotic. In cases where strain interactions were likely, single samples per culture dish were examined with 35 by 10 mm dishes.Bacterial strains. All clinical strains studied were isolated and identified at Veterans Administration Hospital, Cincinnati. These and other locally derived strains are designated with the PL prefix of this laboratory. The origins and pertinent characteristics of the major mating strains are presented in Table 1. Strain PL1 is a leu mutant of strain 280 met rit. 'Ihe mutant was isolated from a stock of the parental strain which had been exposed to diethylsulfate and subjected to carbenicillin selection (1.3 mg/ml). All strains were maintained at room temperature on complex medium solidified with agar (0.75%) in sealed, screw-capped glass vials.Bacterial matings and selection of transcipients.

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Properties of R Plasmids Determining Gentamicin Resistance by Acetylation in Pseudomonas aeruginosa

Cited by 125 publications

References 56 publications

The IncP-6 Plasmid Rms149 Consists of a Small Mobilizable Backbone with Multiple Large Insertions

The IncP-6 Plasmid Rms149 Consists of a Small Mobilizable Backbone with Multiple Large Insertions

Plasmid Modification of Radiation and Chemical-mutagen Sensitivity in Pseudomonas aeruginosa

Pseudomonas aeruginosa R Factors Determining Gentamicin Plus Carbenicillin Resistance from Patients with Urinary Tract Colonizations

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