The arrangement of DNA in lambda phage heads. II. lambda DNA after exposure to micrococcal nuclease at the site of head-tail joining

DNA in lambda phage heads (lacking tails) is damaged by treatment with micrococcal nuclease. Alkaline sucrose gradient sedimentation of the DNA extracted from nuclease-treated and untreated heads reveals no hydrolysis of internal phosphodiester bonds. Transformation of helper-infected cells by whole or half molecules of treated DNA is as efficient as by control DNA. Thus, the site of nuclease damage must be near the ends and very limited.