Physical mapping of bacteriophage lambda DNA with restriction endonuclease HpaI.

The restriction endonuclease from Haemophilus parainfluenzae, endoR.HpaI cleaves lambdacI857s7 DNA into 14 fragments. The sizes of these fragments were determined and a physical map was constructed. The ordering of the fragments was carried out using different deletion and substitution mutants of lambda phage, double cleavages with another restriction enzyme, endoR.BamHI, and partial protection of individual HpaI recognition sites by the antibiotics distamycin A and actinomycin D. HpaI produces fragments from the left arm of the lambda DNA genome, which may help in investigating the structure and function of this part of the phage.