title: Shape of Ocr, the gene 0.3 protein of bacteriophage T7: modeling based on light scattering experiments.
abstract: Ocr, the first protein expressed by bacteriophage T7, inhibits type Iota DNA restriction enzymes by preventing them from binding to DNA. This inhibition allows the phage to successfully infect the host. The shape of ocr is modeled on the basis of static and dynamic light scattering measurements. The static light scattering data confirm previous observations that ocr exists in solution as a dimer. The diffusion constant determined by dynamic light scattering indicates a nonspherical shape of the ocr dimer. Hydrodynamic models of ellipsoids are presented, and it is argued that ocr is best described by a prolate ellipsoid with dimensions of 10.4 nm by 2.6 nm. The size and shape predicted by this model are consistent with ocr acting as a mimic of the DNA structure bound by type Iota restriction enzymes.
authors.affiliation: Department of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3JZ, UK.
authors.forename: J J
authors.initials: JJ
authors.lastname: Blackstock
authors.forename: S U
authors.initials: SU
authors.lastname: Egelhaaf
authors.forename: C
authors.initials: C
authors.lastname: Atanasiu
authors.forename: D T
authors.initials: DT
authors.lastname: Dryden
authors.forename: W C
authors.initials: WC
authors.lastname: Poon
mesh_terms: D017123:Bacteriophage T7 / Q000737:chemistry*; D019281:Dimerization; D008027:Light; D008956:Models, Chemical; D015233:Models, Statistical; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D012542:Scattering, Radiation; D014466:Ultraviolet Rays; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: C440255:Ocr protein, bacteriophage T7; D014764:Viral Proteins