Structure of Ocr from bacteriophage T7, a protein that mimics B-form DNA.
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.
Walkinshaw
M D
MD
Institute of Cell and Molecular Biology, The King's Buildings, University of Edinburgh, EH9 3JR, Edinburgh, United Kingdom. malcolm.walkinsahaw@ed.ac.uk
Taylor
P
P
Sturrock
S S
SS
Atanasiu
C
C
Berge
T
T
Henderson
R M
RM
Edwardson
J M
JM
Dryden
D T F
DT
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*
C440255:Ocr protein, bacteriophage T7; D014764:Viral Proteins; D004247:DNA