An RNA polymerase mutant of Escherichia coli defective in the T4 viral transcription program

Snyder, L. E.

doi:10.1016/0042-6822(72)90391-1

Cited by 28 publications

(12 citation statements)

References 21 publications

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“…This suggests that this genotype may represent the best possible response to the two stresses, or that no other rpoB mutations occurred. Consistent with the former explanation, mutations at the rpoB gene are known to reduce bacterial fitness owing to pleiotropic effects on a variety of transcriptional and physiological processes (Jin and Gross 1989), including growth (Reid 1971), nitrogen metabolism (Ryu 1978), and the ability to support phage growth by altering the mechanism of phage replication within the host bacterium (Snyder 1972; Schwarz et al. 1981).…”

Section: Discussionmentioning

confidence: 93%

“…Little is known about the evolutionary effects of both therapies on bacterial populations, either when applied in sequence or simultaneously. Sequential applications are important to understand, because, for example, the type of mechanism responsible for antibiotic resistance may condition the bacterial response to phage attack (Snyder 1972;Schwarz et al 1981) and therefore the effectiveness of phage therapy. The simultaneous addition of both selective agents may result in the selection of bacterial variants capable of resisting this complex environment.…”

Section: Introductionmentioning

confidence: 99%

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Evolutionary dynamics of separate and combined exposure of Pseudomonas fluorescens SBW25 to antibiotics and bacteriophage

Escobar-Páramo

Gougat-Barberá

Hochberg

2012

Evolutionary Applications

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The use of bacteriophages against pathogenic bacteria in health care and in the food industry is now being advocated as an alternative to the use of antibiotics. But what is the evolutionary response for a bacterial population if both antibiotics and phages are used in combination? We employ an experimental evolution approach to address these questions and exposed Pseudomonas fluorescens SBW25 and a related hypermutator strain (mutS−) to the action of the antibiotic rifampicin and the lytic bacteriophage SBW25ϕ2. We then compared the densities, growth rates, and the mutations at the rpoB locus leading to rifampicin resistance of the evolved bacterial populations. We observed that the evolutionary response of populations under different treatments varied depending on the order in which the antimicrobials were added and whether the bacterium was a hypermutator. We found that wild-type rifampicin-resistant populations involved in biofilm formation often reverted to rifampicin sensitivity when stresses were added sequentially. In contrast, when the mortality agents were added simultaneously, phage populations frequently went extinct and the bacteria evolved antibiotic resistance. However, populations of the hypermutator mutS− converged to a single genotype at the rpoB locus. Future investigation on other bacteria and using different antibiotics and bacteriophage are needed to evaluate the generality of our findings.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Evolutionary dynamics of separate and combined exposure of Pseudomonas fluorescens SBW25 to antibiotics and bacteriophage

Escobar-Páramo

Gougat-Barberá

Hochberg

2012

Evolutionary Applications

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“…Rif' mutations have been found to affect a wide variety of phenotypes, including altered growth properties (10, 16); the ability to support the growth of various bacteriophages (12,18,19); the ability to maintain the F' episome (4); interaction with mutant alleles dnaA(Ts) (2), rpoD(Ts) (15), and strA24 (3); and uracil sensitivity (13). We used our collection of 17 sequenced Rif' mutations (8) …”

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confidence: 99%

Characterization of the pleiotropic phenotypes of rifampin-resistant rpoB mutants of Escherichia coli

1989

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We used our collection of 17 sequenced rifampin resistance alleles in rpoB to perform a systematic analysis of the phenotypes historically reported with this class of mutants, including growth phenotype, ability to support the growth of different bacteriophages, ability to maintain the F' episome, interaction with mutant alleles at other loci, sensitivity to uracil, inhibition by 5-fluorouridine, and dominance. We found that mutational changes leading to the same phenotype were often located together and that certain phenotypes were associated with one another.Historically, Escherichia coli rpoB mutations that confer rifampin resistance (Rif) have been used to probe the involvement of RNA polymerase in a variety of physiological processes. Rif' mutations have been found to affect a wide variety of phenotypes, including altered growth properties (10, 16); the ability to support the growth of various bacteriophages (12,18,19); the ability to maintain the F' episome (4); interaction with mutant alleles dnaA(Ts) (2), rpoD(Ts) (15), and strA24 (3); and uracil sensitivity (13). We used our collection of 17 sequenced Rif' mutations (8)

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“…These results suggest that the RNA polymerase is altered in its recognition of the gene that specifies dihydrofolate reductase.Rifampin and its derivatives are antibiotics that inhibit the activity of the DNA-dependent RNA polymerase by binding to the /3-subunit of the enzvme and preventing the initation of transcription (2, 7). Mutations to r-ifampin resistance have been reported to have pleiotropic effects on complex metabolic processes, such as: a reduced abilitv of Bacillus ssubtilis to sporulate (6,12,13); suppression of dnaA mutations (1); and inhibition of the growth of bacteriophages (11). In addition, alterations in specific enzymes have been reported in some rif nmutants: specifically, an increased level of enzymes in the arginine pathway (17), an increased level of dihvdrofolate (DHF) reductase (M. M. Aldridge, V. J. Wainscott, and J. F. Kane, Abstr.…”

mentioning

confidence: 99%

Increased levels of dihydrofolate reductase in rifampin-resistant mutants of Bacillus subtilis

Kane¹,

Wainscott²,

Hurt³

1979

J Bacteriol

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Several independent, spontaneous rifampin-resistant mautants of Bacillus subtilis were isolated and found to have an increased resistance to trimethoprim, an inhibitor of dihydrofolate reductase. This increased resistance in the rif mutants was the result of a specific threefold increase in the activity of dihydrofolate reductase, since six other enzymes examined remained unchanged. This increased level of dihydrofolate reductase and the trimethoprim resistance were cotransformed (100%') with the i-if marker. These results suggest that the RNA polymerase is altered in its recognition of the gene that specifies dihydrofolate reductase.Rifampin and its derivatives are antibiotics that inhibit the activity of the DNA-dependent RNA polymerase by binding to the /3-subunit of the enzvme and preventing the initation of transcription (2, 7). Mutations to r-ifampin resistance have been reported to have pleiotropic effects on complex metabolic processes, such as: a reduced abilitv of Bacillus ssubtilis to sporulate (6,12,13); suppression of dnaA mutations (1); and inhibition of the growth of bacteriophages (11). In addition, alterations in specific enzymes have been reported in some rif nmutants: specifically, an increased level of enzymes in the arginine pathway (17), an increased level of dihvdrofolate (DHF) reductase (M. M. Aldridge, V. J. Wainscott, and J. F. Kane, Abstr. Annu. Meet. Am. Soc. Microbiol. 1976, K47, p. 144), and the absence of the enzyme glutamate svnthase (10). In this report we present results that show an increased level of DHF reductase in rif mutants of B. subtilis.All of the mutants used in this study were derivatives of the competent strain 168. Spontaneous rifampin-resistant mutants were obtained by surface spreading the gat-7 mutant (previouslI referred to as the trpX7 mutant [4,5]) NP102 on Trypticase soy agar containing (0.6%' yeast extract and 5 ,ig of rifampin (Sigma Chemical Co., St. Louis, Mo.) per ml. The plates were incubated at :370C until resistant colonies appeared. Single colonies were transferred to the rifampin-containing medium anc streaked for isolation. Cultures for enzyme assavs were routinelyr grown in 200 ml of minimal glutcose me-Present address: t)e)artiment of Biolog. (ilemison t Tiversitv, (lenison, NC 29(331. P Present address: Departm-lernt of tell Biology, Baylor College of Medicine, Houston, TIX,770:10.

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An RNA polymerase mutant of Escherichia coli defective in the T4 viral transcription program

Cited by 28 publications

References 21 publications

Evolutionary dynamics of separate and combined exposure of Pseudomonas fluorescens SBW25 to antibiotics and bacteriophage

Evolutionary dynamics of separate and combined exposure of Pseudomonas fluorescens SBW25 to antibiotics and bacteriophage

Characterization of the pleiotropic phenotypes of rifampin-resistant rpoB mutants of Escherichia coli

Increased levels of dihydrofolate reductase in rifampin-resistant mutants of Bacillus subtilis

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