Site-specific recombination of bacteriophage P22 does not require integration host factor

Eun Hee Cho, Chan Eun Nam, Renato Alcaraz, Jeffrey F. Gardner

Research output: Contribution to journalArticlepeer-review


Site-specific recombination by phages λ and P22 is carried out by multiprotein-DNA complexes. Integration host factor (IHF) facilitates λ site-specific recombination by inducing DNA bends necessary to form an active recombinogenic complex. Mutants lacking IHF are over 1,000-fold less proficient in supporting λ site-specific recombination than wild-type cells. Although the attP region of P22 contains strong IHF binding sites, in vivo measurements of integration and excision frequencies showed that infecting P22 phages can perform site-specific recombination to its maximum efficiency in the absence of IHF. In addition, a plasmid integration assay showed that integrative recombination occurs equally well in wild-type and ihfA mutant cells. P22 integrative recombination is also efficient in Escherichia coli in the absence of functional IHF. These results suggest that nucleoprotein structures proficient for recombination can form in the absence of IHF or that another factor(s) can substitute for IHF in the formation of complexes.

Original languageEnglish (US)
Pages (from-to)4245-4249
Number of pages5
JournalJournal of bacteriology
Issue number14
StatePublished - Jul 1999

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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