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dc.contributor.authorShearwin, K.E.en
dc.contributor.authorDodd, I.B.en
dc.contributor.authorEgan, J.B.en
dc.identifier.citationJournal of Biological Chemistry, 2002; 277(5):3186-3194en
dc.description.abstractThe CI protein of coliphage 186 is responsible for maintaining the stable lysogenic state. To do this CI must recognize two distinct DNA sequences, termed A type sites and B type sites. Here we investigate whether CI contains two separate DNA binding motifs or whether CI has one motif that recognizes two different operator sequences. Sequence alignment with 186-like repressors predicts an N-terminal helix-turn-helix (HTH) motif, albeit with poor homology to a large master set of such motifs. The domain structure of CI was investigated by linker insertion mutagenesis and limited proteolysis. CI consists of an N-terminal domain, which weakly dimerizes and binds both A and B type sequences, and a C-terminal domain, which associates to octamers but is unable to bind DNA. A fusion protein consisting of the 186 N-terminal domain and the phage {lambda} oligomerization domain binds A and B type sequences more efficiently than the isolated 186 CI N-terminal domain, hence the 186 C-terminal domain likely mediates oligomerization and cooperativity. Site-directed mutation of the putative 186 HTH motif eliminates binding to both A and B type sites, supporting the idea that binding to the two distinct DNA sequences is mediated by a variant HTH motif.en
dc.description.statementofresponsibilityKeith E. Shearwin, Ian B. Dodd, and J. Barry Eganen
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen
dc.rights© 2002 Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biologyen
dc.subjectEscherichia coli; Coliphages; DNA-Binding Proteins; Recombinant Proteins; Viral Proteins; DNA Primers; Chromosome Mapping; Mutagenesis, Insertional; Sequence Alignment; Binding Sites; Amino Acid Sequence; Base Sequence; Helix-Turn-Helix Motifs; Zinc Fingers; Sequence Homology, Amino Acid; Kinetics; Molecular Sequence Data; Promoter Regions, Geneticen
dc.titleThe helix-turn-helix motif of the coliphage 186 immunity repressor binds to two distinct recognition sequencesen
dc.typeJournal articleen
pubs.library.collectionMolecular and Biomedical Science publicationsen
Appears in Collections:Molecular and Biomedical Science publications

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