The molecular nature of R-factors

Falkow, Stanley; Citarella, R. V.; Wohlhieter, J. A.; Watanabe, Tsutomu

doi:10.1016/s0022-2836(66)80097-9

Cited by 123 publications

(62 citation statements)

References 22 publications

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“…Such resistance results from the presence in the bacteria of a non-chromosomal genetic determinant or plasmid, termed an R factor, composed of DNA of a characteristic base composition (Falkow, Citarella, Wohlhieter & Watanabe, 1966). R factors reported from Japan commonly confer * Present address: Department of Physiology and Biochemistry, University of Southampton, Southampton, SOg 5NH.…”

Section: Introductionmentioning

confidence: 99%

R (Transmissible Drug-resistance) Factors in Salmonella typhimurium: Pattern of Transduction by Phage P22 and Ultraviolet-protection Effect

Drabble

Stocker

1968

Journal of General Microbiology

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S U M M A R YR factors from Enterobacter strains isolated outside Japan were transferred to Salmonella typhimurium LT 2 and their resistance traits transduced by phage P 22. Of five$+ factors conferring resistance to tetracycline (Tc), streptomycin (Sm), sulphonamides (Su) and chloramphenicol (Cm), three, one of which conferred also resistance to kanamycin (Km), behaved like previously reported factors in that: Tc was transduced by itself but never with any other trait; all other traits were usually co-transduced; no transductants could transmit resistance by conjugation, even after infection with F'-13 lac. The other two $+ factors, which conferred also resistance to benzylpenicillin (Pn), behaved similarly, except that : Pn was transduced only at a low rate, and was never co-transduced with any other trait; and a few transductants when given F'-13 lac became able to transmit. Four $-factors, two of type Tc, Sm, Su, Pn and two of type Tc, Su, Pn differed in that : nearly all Tc transductants acquired also all the other traits; Pn was usually co-transduced with the other traits ; and some transductants could transmit by conjugation, even without F'-I 3 lac. The various transductant classes obtained by treatment with P 22 grown on LT 2 carrying both an$+ (Tc, Sm, Su, Cm, Km) and$-(Tc, Sm, Su, Pn) factor could be accounted for by transduction of fragments of either one or the other of these factors. The sorts of transductants produced by lysates of a strain possessing Tc, Sm, Su, Cm, Km determinants obtained by growing a strain carrying a n 3 + (Tc, Sm, Su, Cm) factor with one carrying an$+ (Km) factor suggested that the strain carried two $+ factors, not a recombinant factor. Both Ji-and $+ factors conferring resistance to benzylpenicillin conferred also resistance to cephalothin and cephaloridine and caused the constitutive production of a 1-lactamase, active on both benzylpenicillin and on cephalothin. All four-fi-and one of the five$+ factors resembled colI factors in that they protected strain LT 2 against the bactericidal effect of ultraviolet irradiation.

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Section: Introductionmentioning

confidence: 99%

R (Transmissible Drug-resistance) Factors in Salmonella typhimurium: Pattern of Transduction by Phage P22 and Ultraviolet-protection Effect

Drabble

Stocker

1968

Journal of General Microbiology

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“…Proc., p. 67, 1969) that among bacterial plasmid eliminating chemicals one category was comprised of substances that bind to deoxyribonucleic acid (DNA) by intercalation (15,20,30,31). After it had been shown that Rfactors chemically are DNA (11) and that bacteria from which all resistance determinants had been eliminated no longer contained -factor DNA (8,25), we assumed that intercalative eliminators of R-factors act by selective complexation with plasmid DNAs and, thereby, selectively inhibit their replication.…”

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confidence: 99%

Elimination of Resistance Determinants from R-Factor R1 by Intercalative Compounds

Hahn

Ciak

1976

Antimicrob Agents Chemother

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Eighteen deoxyribonucleic acid (DNA)-complexing compounds, among them 15 intercalative substances, and, additionally, nalidixic acid eliminated with different frequencies four antibiotic resistance determinants from the R-factor R1, carried by Salmonella typhimurium . Eliminating concentrations did not inhibit growth of the bacteria. The most active compound was “nitroacridine II” {1-diethylamino-3-[(6-nitro-9-acridinyl)amino]propanol}. When 14 compounds which had been tested at a standard concentration of 10 −4 M were listed according to decreasing activities of elimination of the four resistance determinants, a nearly consistent activity sequence was revealed. Frequencies of elimination of the kanamycin resistance determinant correlated directly with the binding of compounds to DNA, i.e., with end points of their displacement of methyl green from the methyl green-DNA complex. We propose that the observed eliminations resulted from selective toxicity for plasmidic template DNA and inhibitions of R-factor replication.

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“…R-factors of the fi+ type were found to con sist of two distinct DNA subfractions with overall base compositions of 50 to 52 per cent G + C and 56 to 58 per cent G + e (113,190). The sponta neous loss of one or more drug resistance determinants carried by R-fac tors was found to be a physical deletion of R-factor DNA (190). The re duction in DNA content associated with loss of a resistance determinant was not random, but rather specific regions of the R-factor were observed to be deleted or modified.…”

Section: Extrachromosomal Elementsmentioning

confidence: 97%