Arm site independence of coliphage HK022 integrase in human cells

Natalia Malchin, Chen N. Tuby, Ezra Yagil, Mikhail Kolot*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The integrase encoded by the lambdoid phage HK022 (Int-HK022) resembles its coliphage λ counterpart (Int-λ) in the roles of the cognate DNA arm binding sites and in controlling the direction of the reaction. We show here that within mammalian cells, Int-HK022 does not exhibit such a control. Rather, Int-HK022 recombined between all ten possible pairwise att site combinations, including attB × attB that was more effective than the conventional integrative attP × attB reaction. We further show that Int-HK022 depends on the accessory integration host factor (IHF) protein considerably less than Int-λ and exhibits stronger binding affinity to the att core. These differences explain why wild-type Int-HK022 is active in mammalian cells whereas Int-λ is active there only as an IHF-independent mutant.

Original languageEnglish
Pages (from-to)403-413
Number of pages11
JournalMolecular Genetics and Genomics
Issue number5
StatePublished - May 2011


  • Coliphage HK022
  • Human embryonic kidney cell culture
  • Integrase
  • Site-specific recombination


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