Site-specific recombination of bacteriophage P22 does not require integration host factor.
Site-specific recombination by phages lambda and P22 is carried out by multiprotein-DNA complexes. Integration host factor (IHF) facilitates lambda 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 lambda 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.
Cho
E H
EH
Department of Science Education, Kwangju 501-759, Korea, and Department of Microbiology, University of Illinois, Urbana, Illinois 61801, USA. ehcho@chosum.ac.kr
Nam
C E
CE
Alcaraz
R
R
Gardner
J F
JF
D001287:Attachment Sites, Microbiological; D001426:Bacterial Proteins / Q000378:metabolism*; D017100:Bacteriophage P22 / Q000235:genetics* / Q000502:physiology; D004926:Escherichia coli / Q000821:virology; D034982:Integration Host Factors; D008242:Lysogeny; D010957:Plasmids / Q000235:genetics; D011995:Recombination, Genetic; D012486:Salmonella typhimurium / Q000821:virology*; D014775:Virus Activation; D016662:Virus Integration / Q000502:physiology*
D001426:Bacterial Proteins; D034982:Integration Host Factors; C440508:integration host factor, Salmonella