Use of the antibiotics actinomycin D and distamycin A to limit the action of restriction endonucleases and to map DNA

It is shown that distamycin A and actinomycin D protect the recognition sites of certain restriction endonucleases from the attack by these nucleases due to specific interaction of these antibiotics with double-stranded DNA. Distamycin A protects A-T containing sites and actinomycin G-C rich sites. Among Hind II recognition sites which have alternative structure (GTPyPuAC) distamycin A protects only Hpa I similar sites (GTTAAC). It is shown with several restriction endonucleases that antibiotic action depends on the nucleotide sequences in the recognition sites and in their closest environment. Proper concentrations of antibiotic give rise to larger fragments. Use of both distamycin A and actinomycin D allows to obtain a set of overlapping fragments. The data obtained with various DNAs and restriction endonucleases allow to conclude that these antibiotics may be useful for DNA mapping and for preparation of large functional fragments of DNA.