Resolution of branched DNA substrates by T7 endonuclease I and its inhibition

Min Lu, Qiu Guo, F. William Studier, Neville R. Kallenbach

Research output: Contribution to journalArticlepeer-review


Endonuclease I is a multipurpose enzyme implicated in the breakdown of host DNA, packaging of phage DNA, and recombination during the lytic cycle of bacteriophage T7. We investigate here some aspects of the substrate requirements for its activity in resolving branched intermediates similar to Holliday junctions (Holliday, R. (1964) Genet. Res. 5, 282-304) that arise in recombination. The enzyme is able to resolve branched substrates containing very short duplex arms: 4 base pairs suffice. It cleaves 5′ to the branch, with a distinct preference for the non-crossover strands in Holliday-like model junctions. Ligands that interact strongly with the branch site can inhibit the enzyme, with KI values in the 10-50 μM range.

Original languageEnglish (US)
Pages (from-to)2531-2536
Number of pages6
JournalJournal of Biological Chemistry
Issue number4
StatePublished - Feb 5 1991

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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