Structure-function studies of the bacteriophage T4 DNA polymerase. Isolation of a novel suppressor mutant

J Mol Biol. 1985 Dec 5;186(3):505-14. doi: 10.1016/0022-2836(85)90125-1.


We describe here our first attempt in using suppressor mutations to study structure-function relationships of the bacteriophage T4 DNA polymerase. One intragenic suppressor mutation, J5(43) degrees, was isolated that suppresses the temperature sensitivity but not the mutator activity of tsM19, a DNA polymerase mutant. Thus, the substituted amino acid induced by the tsM19 lesion decreases DNA polymerase fidelity, even if the temperature sensitivity has been corrected by a second amino acid substitution in the DNA polymerase polypeptide. The isolation, mapping and characterization of the J5(43) degrees mutation as well as the purification and characterization of the tsM19-J5(43) degrees mutant DNA polymerase are presented. The suppressor isolation procedure has general applicability for the selection of suppressor mutations of other T4 DNA polymerase mutator mutants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acriflavine / metabolism
  • Crossing Over, Genetic
  • DNA-Directed DNA Polymerase / genetics*
  • DNA-Directed DNA Polymerase / metabolism
  • Deoxyribonucleases / metabolism
  • Drug Resistance, Microbial
  • Genes, Viral
  • Mutation
  • Structure-Activity Relationship
  • Suppression, Genetic*
  • T-Phages / enzymology
  • T-Phages / genetics*
  • Temperature


  • Acriflavine
  • DNA-Directed DNA Polymerase
  • Deoxyribonucleases