title: Functional interactions beween the DNA ligase of Escherichia coli and components of the DNA metabolic apparatus of T4 bacteriophage.
abstract: T4 phage completely defective in both gene 30 (DNA ligase) and the rII gene (function unknown) require at least normal levels of host-derived DNA ligase (E. coli lig gene) for growth. Viable E. coli mutant strains that harbor less than 5% of the wild-type level of bacterial ligase do not support growth of T4 doubly defective in genes 30 and rII (T4 30- rII- mutants). We describe here two classes of secondary phage mutations that permit the growth of T4 30- rII- phage on ligase-defective hosts. One class mapped in T4 gene su30 (Krylov 1972) and improved T4 30- rII- phage growth on all E. coli strains, but to varying degrees that depended on levels of residual host ligase. Another class mapped in T4 gene 32 (helix-destabilizing protein) and improved growth specifically on a host carrying the lig2 mutation, but not on a host carrying another lig- lesion (lig4). Two conclusions are drawn from the work: (1) the role of DNA ligase in essential DNA metabolic processes in T4-infected E. coli is catalytic rather than stoichiometric, and (2) the E. coli DNA ligase is capable of specific functional interactions with components of the T4 DNA replication and/or repair apparatus.
mesh_terms: D003090:Coliphages / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D011088:DNA Ligases / Q000235:genetics*; D004260:DNA Repair; D004261:DNA Replication; D004279:DNA, Viral / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D009154:Mutation; D010641:Phenotype; D011118:Polynucleotide Ligases / Q000235:genetics*
chemical_list: D004279:DNA, Viral; D011088:DNA Ligases; D011118:Polynucleotide Ligases