Specificity determinants in the attachment sites of bacteriophages HK022 and lambda.
AUTOR(ES)
Nagaraja, R
RESUMO
The Int proteins of bacteriophages HK022 and lambda promote recombination between phage and bacterial attachment sites. Although the proteins and attachment sites of the two phages are similar, neither protein promotes efficient recombination between the pair of attachment sites used by the other phage. To analyze this difference in specificity, we constructed and characterized chimeric attachment sites in which segments of one site were replaced with corresponding segments of the other. Most such chimeras recombined with appropriate partner sites in vivo and in vitro, and their differential responses to the Int proteins of the two phages allowed us to locate determinants of the specificity difference in the bacterial attachment sites and a central segment of the phage attachment sites. The location of these determinants encompasses three of the four core-type binding sites for lambda Int: C, B, and most importantly, B'. The regions corresponding to the C' core binding site and the arm-type binding sites of lambda Int play no role in the specificity difference and, indeed, are well conserved in the two phages. We found, unexpectedly, that the effect of replacement of an Int-binding region on the recombinational potency of one chimeric site was reversed by a change of partner. This novel context effect suggests that postsynaptic interactions affect the specificity of recognition of attachment sites by Int.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=526843Documentos Relacionados
- Interaction between the phage HK022 Nun protein and the nut RNA of phage lambda.
- A segment of the phage HK022 chromosome is a mosaic of other lambdoid chromosomes.
- Phage HK022 Nun protein represses translation of phage λ N (transcription termination/translation repression)
- Phage HK022 Roi protein inhibits phage lytic growth in Escherichia coli integration host factor mutants.
- The Nun protein of bacteriophage HK022 inhibits translocation of Escherichia coli RNA polymerase without abolishing its catalytic activities