title: Structure of Ocr from bacteriophage T7, a protein that mimics B-form DNA.
abstract: We have solved, by X-ray crystallography to a resolution of 1.8 A, the structure of a protein capable of mimicking approximately 20 base pairs of B-form DNA. This ocr protein, encoded by gene 0.3 of bacteriophage T7, mimics the size and shape of a bent DNA molecule and the arrangement of negative charges along the phosphate backbone of B-form DNA. We also demonstrate that ocr is an efficient inhibitor in vivo of all known families of the complex type I DNA restriction enzymes. Using atomic force microscopy, we have also observed that type I enzymes induce a bend in DNA of similar magnitude to the bend in the ocr molecule. This first structure of an antirestriction protein demonstrates the construction of structural mimetics of long segments of B-form DNA.
authors.affiliation: Institute of Cell and Molecular Biology, The King's Buildings, University of Edinburgh, EH9 3JR, Edinburgh, United Kingdom. malcolm.walkinsahaw@ed.ac.uk
authors.forename: M D
authors.initials: MD
authors.lastname: Walkinshaw
authors.forename: P
authors.initials: P
authors.lastname: Taylor
authors.forename: S S
authors.initials: SS
authors.lastname: Sturrock
authors.forename: C
authors.initials: C
authors.lastname: Atanasiu
authors.forename: T
authors.initials: T
authors.lastname: Berge
authors.forename: R M
authors.initials: RM
authors.lastname: Henderson
authors.forename: J M
authors.initials: JM
authors.lastname: Edwardson
authors.forename: D T F
authors.initials: DT
authors.lastname: Dryden
mesh_terms: D017123:Bacteriophage T7 / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: C440255:Ocr protein, bacteriophage T7; D014764:Viral Proteins; D004247:DNA