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R-factor-mediated nuclease activity involved in thymineless elimination.

Abstract
R-factor 1818 (R-1818) had no effect on the efficiency of plating of ligase-deficient phage T4 mutants on strains of Escherichia coli containing excess, normal, or defective ligase. However, if the R(+) bacterial strain that overproduced ligase was first starved of thymine, its ability to propagate ligase-deficient phage was reduced by as much as fivefold compared with the burst size on the thymine-starved R(-) strain. In contrast, it was found that after ultraviolet irradiation of the host the phage burst size was higher on the R(+) ligase overproducing strain than the R(-) derivative. The maximal level of R-factor elimination produced by thymine starvation was inversely related to the ligase level of the host. Ultraviolet irradiation did not cure the R factor from strains containing wild-type levels of ligase, but did cause elimination from strains with excess or defective ligase. The results suggest that R-1818 codes for a nuclease that is induced by thymine starvation and which, possibly in conjunction with host-mediated nucleases, is responsible for its elimination under these conditions.
AuthorsD J Tweats, R J Pinney, J T Smith
JournalJournal of bacteriology (J Bacteriol) Vol. 118 Issue 3 Pg. 790-5 (Jun 1974) ISSN: 0021-9193 [Print] United States
PMID4598004 (Publication Type: Journal Article)
Chemical References
  • Anti-Bacterial Agents
  • Deoxyribonucleases
  • Ligases
  • Thymine
Topics
  • Anti-Bacterial Agents (pharmacology)
  • Coliphages (enzymology, growth & development)
  • DNA Viruses
  • Deoxyribonucleases (metabolism)
  • Drug Resistance, Microbial
  • Escherichia coli (drug effects, enzymology, metabolism, radiation effects)
  • Extrachromosomal Inheritance
  • Ligases (metabolism)
  • Mutation
  • Radiation Effects
  • Thymine (metabolism)
  • Ultraviolet Rays
  • Viral Plaque Assay

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