Sequence analysis of the nicks and termini of bacteriophage T5 DNA.

Bacteriophage T5 DNA, when isolated from mature phage particles, contains several nicks in one of the two strands. The 5'-terminal nucleotides at the nicks were labeled with polynucleotide kinase and [gamma-32P]ATP, and the 3'-terminal nucleotides were labeled with Escherichia coli DNA polymerase I and [alpha-32P]dGTP. The sequences around the nicks were analyzed by partial nuclease digestion followed by homochromatography fractionation of the resulting oligonucleotides. The nicks had at least the sequence -PuOH pGpCpGpC- in common. In addition, the two 5' external termini had the first seven nucleotides in common.