title: DNA ligase mutants of Escherichia coli.
abstract: A procedure is described for the isolation of Escherichia coli mutants with either excess or deficient DNA ligase activity. A mutant that overproduces DNA ligase supports the growth of ligase-defective (gene 30 mutant) T4 phages. Even T4 rII-gene 30 double mutants, which are able to grow in normal E. coli, cannot grow in cells deficient in DNA ligase. A functional DNA ligase, supplied either by the phage or the host, thus seems to be required for T4 growth. An E. coli strain that makes a temperature-sensitive DNA ligase becomes radiation-sensitive at high temperature, but otherwise grows normally and shows no obvious defect in DNA replication.
mesh_terms: D002499:Centrifugation, Density Gradient; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000201:enzymology*; D005827:Genetics, Microbial; D008025:Ligases / Q000378:metabolism*; D009154:Mutation; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D008025:Ligases