title: Lambda cro repressor complex with OR3 operator DNA. 19F nuclear magnetic resonance observations.
abstract: The interaction of lambda cro repressor with DNA is probed using synthetic 17 base-pair OR3 operators in which 5-fluorodeoxyuridine has been systematically incorporated at each of the nine positions normally occupied by a thymidine residue. By monitoring changes in chemical shift of the fluorine resonances upon cro repressor binding in aqueous buffers of varying 2H2O content, we have examined the specific cro repressor-OR3 DNA complex in detail. The results are interpreted in the context of the popular model for cro repressor-OR3 complex derived from the three-dimensional structure of the cro repressor in the absence of DNA. The results presented here not originally predicted by the model are: (1) there is an asymmetry in the environment at the two ends of the operator, although the base-pairs involved and the cro repressor dimer are symmetric; (2) there appears to be distortion of the DNA helix at two distinct positions; (3) changes of the DNA environment in the middle of the helix suggest additional DNA distortion not near the contact areas proposed in the model.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia 19104.
authors.forename: W J
authors.initials: WJ
authors.lastname: Metzler
authors.forename: P
authors.initials: P
authors.lastname: Lu
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D015342:DNA Probes; D004279:DNA, Viral / Q000235:genetics*; D004268:DNA-Binding Proteins; D004926:Escherichia coli; D005461:Fluorine; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008957:Models, Genetic; D009875:Operator Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D015342:DNA Probes; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D005461:Fluorine