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Microbiological Reviews Dec 1988
Comparative Study Review
Topics: Bacteria; Drug Resistance, Microbial; Genes, Bacterial; R Factors
PubMed: 3070319
DOI: 10.1128/mr.52.4.433-451.1988 -
Journal of Bacteriology Aug 1975Phages lambda and fd were propagated in Escherichia coli strains that have either host K-12 or the N-3 R-factor deoxyribonucleic acid-cytosine methylase activity....
Phages lambda and fd were propagated in Escherichia coli strains that have either host K-12 or the N-3 R-factor deoxyribonucleic acid-cytosine methylase activity. Pyrimidine tracts containing 3H-labeled 5-methylcytosine (MeC) were analyzed; in all cases, the major methylated sequence was 5' ... C-MeC-T ... 3'.
Topics: Base Sequence; Coliphages; DNA (Cytosine-5-)-Methyltransferases; DNA, Viral; Drug Resistance, Microbial; Escherichia coli; Genes; Methylation; Methyltransferases; R Factors
PubMed: 1097428
DOI: 10.1128/jb.123.2.768-770.1975 -
Journal of Bacteriology Jan 1988The aacA1 gene, which encodes a 6'-N-acetyltransferase [AAC(6')-I] mediating resistance to kanamycin, tobramycin, and amikacin, was cloned from the Citrobacter diversus...
The aacA1 gene, which encodes a 6'-N-acetyltransferase [AAC(6')-I] mediating resistance to kanamycin, tobramycin, and amikacin, was cloned from the Citrobacter diversus R plasmid pBWH100 into the Escherichia coli vector pBR322. The complete nucleotide sequence of the gene and flanking regions was determined. A protein of approximately 21 kilodaltons was identified when the chimeric plasmid encoding the aacA1 gene was introduced into E. coli maxicells. This value is consistent with the size predicted for a protein translated from the open reading frame of the gene.
Topics: Acetyltransferases; Amino Acid Sequence; Base Sequence; Citrobacter; Cloning, Molecular; DNA Restriction Enzymes; DNA, Bacterial; Drug Resistance, Microbial; Genes, Bacterial; Molecular Sequence Data; R Factors
PubMed: 2826403
DOI: 10.1128/jb.170.1.471-473.1988 -
Nucleic Acids Research Dec 1984We have completed the pSC101 sequence. The coding capacities of the newly sequenced regions show the presence of two large open reading frames close to the oriT region....
We have completed the pSC101 sequence. The coding capacities of the newly sequenced regions show the presence of two large open reading frames close to the oriT region. Their size and localization suggest that these polypeptide chains could be involved in the transfer process of pSC101.
Topics: Base Sequence; Conjugation, Genetic; DNA Restriction Enzymes; DNA, Bacterial; Hydrogen Bonding; Nucleic Acid Conformation; Plasmids; R Factors; Salmonella
PubMed: 6096829
DOI: 10.1093/nar/12.24.9415 -
Antimicrobial Agents and Chemotherapy May 1975The newly introduced semisynthetic aminoglycoside antibiotics, i.e., 3',4'-dideoxykanamycin B (DKB), 6'-N-methyl DKB (6'-Me-DKB) and amikacin (AK) have been found to be...
The newly introduced semisynthetic aminoglycoside antibiotics, i.e., 3',4'-dideoxykanamycin B (DKB), 6'-N-methyl DKB (6'-Me-DKB) and amikacin (AK) have been found to be effective against gram-negative pathogens including Pseudomonas aeruginosa, which are resistant to the known aminoglycoside antibiotics. We have demonstrated in our stock cultures two types of P. aeruginosa strains resistant to DKB, i.e., (DKB(r).AK(r).6'-Me-DKB(s)) and (DKB(r).AK(s).6'-Me-DKB(r)) (where r = resistant; s = sensitive). Both groups of strains inactivate the drugs by acetylation. The acetylating enzyme was extracted from GN4925(DKB(r).AK(s).6'-Me-DKB(r)) and purified by affinity chromatography. Enzymatic studies of the inactivation reaction and chemical studies of the inactivated products indicated that DKB and 6'-Me-DKB were inactivated by acetylation of the 6'-amino group of the drugs. This enzyme acetylates kanamycin A (KM-A), KM-B, DKB, 6'-Me-DKB, 6'-N-methyl kanamycin B, but not KM-C, AK, and gentamicin C(1). The enzyme is named aminoglycoside 6'-N-acetyltransferase 3. Genetic studies of two strains resistant to DKB and 6'-Me-DKB disclosed that the enzyme catalyzing inactivation of both DKB and 6'-Me-DKB was mediated by an R factor, i.e., R(ms167) and R(ms168), capable of conferring resistance to KM, DKB, and 6'-Me-DKB, in addition to resistance to gentamicin, streptomycin, and sulfanilamide, and resistance to tetracycline, chloramphenicol, streptomycin and sulfanilamide respectively.
Topics: Acetyltransferases; Aminoglycosides; Anti-Bacterial Agents; Drug Resistance, Microbial; Pseudomonas aeruginosa; R Factors
PubMed: 807154
DOI: 10.1128/AAC.7.5.494 -
Antimicrobial Agents and Chemotherapy Feb 2003Quinolone resistance encoded by the qnr gene and mediated by plasmid pMG252 was discovered in a clinical strain of Klebsiella pneumoniae that was isolated in 1994 at the...
Quinolone resistance encoded by the qnr gene and mediated by plasmid pMG252 was discovered in a clinical strain of Klebsiella pneumoniae that was isolated in 1994 at the University of Alabama at Birmingham Medical Center. The gene codes for a protein that protects DNA gyrase from quinolone inhibition and that belongs to the pentapeptide repeat family of proteins. The prevalence of the gene has been investigated by using PCR with qnr-specific primers with a sample of more than 350 gram-negative strains that originated in 18 countries and 24 states in the United States and that included many strains with plasmid-mediated AmpC or extended spectrum beta-lactamase enzymes. qnr was found in isolates from the University of Alabama at Birmingham only during 6 months in 1994, despite the persistence of the gene for FOX-5 beta-lactamase, which is linked to qnr on pMG252. Isolates from other locations were negative for qnr. The prevalence of mcbG in the same sample was also examined. mcbG encodes another member of the pentapeptide repeat family and is involved in immunity to microcin B17, which, like quinolones, targets DNA gyrase. A single clinical isolate contained mcbG on a transmissible R plasmid. This plasmid and one carrying the complete microcin B17 operon slightly decreased sparfloxacin susceptibility but had a much less protective effect than pMG252. Plasmid-mediated quinolone resistance was thus rare in the sample examined.
Topics: Anti-Infective Agents; Drug Resistance, Bacterial; Escherichia coli; Fluoroquinolones; Klebsiella pneumoniae; Microbial Sensitivity Tests; Prevalence; R Factors
PubMed: 12543659
DOI: 10.1128/AAC.47.2.559-562.2003 -
Journal of Bacteriology Dec 1975We are engaged in the genetic and physical characterization of an enterotoxin (Ent) plasmid, Ent P307, which contains genes for the production of a hear-labile and a...
We are engaged in the genetic and physical characterization of an enterotoxin (Ent) plasmid, Ent P307, which contains genes for the production of a hear-labile and a heat-stable enterotoxin. We are using an Escherichia coli K-12 strain, 711 (P307), constructed by S. Falkow, which contains no other plasmids besides Ent P307. Our genetic studies have shown that the plasmid is incompatible with the sex factor F, both in the integrated (Hfr) and the autonomous (F-prime) state. Ent P307 can thus be assigned to incompatibility group FI. An R factor, R386, which belongs to the same incompatibility group, was also found to be incompatibile with Ent P307, whereas five other R factors belonging to different incompatibility groups were compatible with Ent P307. In the presence of Ent P307, conjugal transfer and sensitivity to a male-specific phage of a derepressed F-like R factor, R1drd19, were repressed. Ent P307 is, thus, finO+. Presumably, it also causes repression of its own transfer genes since conjugal transfer of Ent P307 could not be demonstrated. Unlike F, it does not restrict the growth of female-specific phage phiII. From physical studies on extracted deoxyribonucleic acid, the molecular weight of Ent P307 was determined to be 54 X 10(6). By electron microscope heteroduplex analysis, the plasmid was found to be homologous with F in four regions, encompassing about half of its length. One long region and two short ones contain genes for conjugal transfer; the other short region carries genes for replication and incompatibility.
Topics: Conjugation, Genetic; DNA, Bacterial; DNA, Circular; Enterotoxins; Escherichia coli; Extrachromosomal Inheritance; F Factor; Genes; Hot Temperature; Microscopy, Electron; Mutation; Nucleic Acid Conformation; Plasmids; R Factors; Recombination, Genetic
PubMed: 1104580
DOI: 10.1128/jb.124.3.1240-1247.1975 -
Journal of Bacteriology Jan 1977Mating aggregates during conjugation directed by an F-like R factor in Escherichia coli were measured as the number of Lac+-Lac- sectored colonies present in a mating...
Mating aggregates during conjugation directed by an F-like R factor in Escherichia coli were measured as the number of Lac+-Lac- sectored colonies present in a mating mixture. There is a high degree of correlation between the concentration of transconjugants produced in a mating mixture and the concentration of mating aggregates observed at several different concentrations of donor and recipient cells. The mating aggregates are sex pilus specific as demonstrated by the ability of donor-specific ribonucleic acid phage MS-2 to decrease both mating aggregates and transconjugants in a mating mixture. During entry exclusion by either a derepressed or a repressed F-like R factor, isogenic to the superinfecting R factor except for a resistance determinant, the number of transconjugants was markedly reduced, but the number of mating aggregates was not decreased. Entry exclusion by F-Gal toward the donor HfrH resembled that of the F-like R factor in that there was a reduction in the number of recombinants but no significant decrease in mating aggregates. These results suggest that entry exclusion inhibits conjugation at a stage after the formation of mating aggregates.
Topics: Conjugation, Genetic; Escherichia coli; F Factor; Kinetics; R Factors
PubMed: 318636
DOI: 10.1128/jb.129.1.131-137.1977 -
Antimicrobial Agents and Chemotherapy Jul 1976Nineteen of 39 multiresistant strains of Serratia marcescens isolated from clinical sources transferred antibiotic resistance to Escherichia coli or Klebsiella...
Nineteen of 39 multiresistant strains of Serratia marcescens isolated from clinical sources transferred antibiotic resistance to Escherichia coli or Klebsiella pneumoniae recipients. Marcesins and/or phage prevented effective resistance transfer to E. coli and attempts to select marcescin-resistant mutants of the E. coli recipient strain were unsuccessful. Transfer of resistance was demonstrated for all drugs tested except nalidixic acid. Approximately 90% of donors resistant to tobramycin, ampicillin, or carbenicillin transferred resistance to these drugs. High levels of transferred resistance (minimal inhibitory concentration, >2,500 mug/ml) were demonstrated particularly for ampicillin, carbenicillin, and kanamycin. Transmissibility of Serratia R factors was greatest between isogeneic strains of E. coli K-12. Comparative rates of spontaneous loss of R factor-mediated resistance indicated that Serratia R factors are less stable in E. coli and K. pneumoniae transcipients than in the indigenous hosts.
Topics: Bacteriocins; Conjugation, Genetic; Drug Resistance, Microbial; Escherichia coli; Klebsiella pneumoniae; R Factors; Serratia marcescens
PubMed: 791085
DOI: 10.1128/AAC.10.1.123 -
Journal of Bacteriology May 1995In addition to conferring resistances to antibiotics and heavy metals, certain R factors carry genes involved in mutagenic DNA repair. These plasmid-encoded genes are... (Comparative Study)
Comparative Study
In addition to conferring resistances to antibiotics and heavy metals, certain R factors carry genes involved in mutagenic DNA repair. These plasmid-encoded genes are structurally and functionally related to the chromosomally encoded umuDC genes of Escherichia coli and Salmonella typhimurium. Three such plasmid operons, mucAB, impCAB, and samAB, have been characterized at the molecular level. Recently, we have identified three additional umu-complementing operons from IncJ plasmid R391 and IncL/M plasmids R446b and R471a. We report here the molecular characterization of the R391 umu-complementing operon. The nucleotide sequence of the minimal R plasmid umu-complementing (rum) region revealed an operon of two genes, rumA(R391) and rumB(R391), with an upstream regulatory signal strongly resembling LexA-binding sites. Phylogenetic analysis revealed that the RumAB(R391) proteins are approximately equally diverged in sequence from the chromosomal UmuDC proteins and the other plasmid-encoded Umu-like proteins and represent a new subfamily. Genetic characterization of the rumAB(R391) operon revealed that in recA+ and recA1730 backgrounds, the rumAB(R391) operon was phenotypically indistinguishable from mucAB. In contrast, however, the rumAB(R391) operon gave levels of mutagenesis that were intermediate between those given by mucAB and umuDC in a recA430 strain. The latter phenotype was shown to correlate with the reduced posttranslational processing of the RumA(R391) protein to its mutagenically active form, RumA'(R391). Thus, the rumAB(R391) operon appears to possess characteristics that are reminiscent of both chromosome and plasmid-encoded umu-like operons.
Topics: Amino Acid Sequence; Bacterial Proteins; Base Sequence; DNA Repair; DNA-Directed DNA Polymerase; Escherichia coli; Escherichia coli Proteins; Genes, Bacterial; Genetic Complementation Test; Molecular Sequence Data; Mutagenesis; Operon; Phylogeny; R Factors; Regulatory Sequences, Nucleic Acid; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Ultraviolet Rays
PubMed: 7751283
DOI: 10.1128/jb.177.10.2737-2743.1995