title: Base sequence-specific interactions of operator DNA fragments with the lambda-cro repressor coupled with changes in their conformations.
abstract: The mechanism of interaction of the operator DNA with the lambda-cro repressor protein was investigated using proton n.m.r. and photo CIDNP. Three kinds of DNA duplexes, the lambda-OR3 17-mer, phi80-OR2 19-mer and CRP binding site 22-mer, were prepared, and all of their imino proton resonances of the complexes with lambda-cro were assigned to individual base pairs. By monitoring the assigned signals of the DNA fragments and lambda-cro, it was found that in the complex of lambda-cro with lambda-OR3, two subunits of the cro dimer bind to the right and left halves of the OR3, respectively, and the bidentate binding induces a structural distortion in the middle of the 17-mer. lambda-cro itself also undergoes a conformational change including loosening of the dimeric form. In the complex of lambda-cro with phi 80-OR2, which has a 6-bp sequence common to that of lambda-OR3, one subunit of the cro dimer seems to bind specifically to the common part. However, there is only a slight conformational change in the cro dimer. In the mixture of the CRP binding site 22-mer and lambda-cro, soft contact without any conformational change was observed between them.
authors.forename: S J
authors.initials: SJ
authors.lastname: Lee
authors.forename: M
authors.initials: M
authors.lastname: Shirakawa
authors.forename: H
authors.initials: H
authors.lastname: Akutsu
authors.forename: Y
authors.initials: Y
authors.lastname: Kyogoku
authors.forename: M
authors.initials: M
authors.lastname: Shiraishi
authors.forename: K
authors.initials: K
authors.lastname: Kitano
authors.forename: M
authors.initials: M
authors.lastname: Shin
authors.forename: E
authors.initials: E
authors.lastname: Ohtsuka
authors.forename: M
authors.initials: M
authors.lastname: Ikehara
mesh_terms: D001483:Base Sequence; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005798:Genes, Bacterial; D009682:Magnetic Resonance Spectroscopy; D009875:Operator Regions, Genetic; D010957:Plasmids; D011485:Protein Binding; D011487:Protein Conformation; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins