Function of gene 49 of bacteriophage T4 III. Isolation of Holliday structures from very fast-sedimenting DNA.

Branched DNA molecules were identified in ClaI digests of cytosine containing very fast-sedimenting DNA (VFS-DNACYT) which was isolated from Escherichia coli infected with the multiple mutant 49-GT7 of phage T4. In about 10% of randomly picked ClaI fragments branches with three arms (Y-structures) as well as four arms (Holliday structures) were seen in the electron microscope. Branched structures were absent from ClaI digests after treatment with purified endonuclease VII (gp49) in vitro.