title: [Antirestriction activity of T7 Ocr protein in monomeric and dimeric forms].
abstract: The Ocr protein, encoded by 0.3 (ocr) gene of bacteriophage T7, belongs to the family of antirestriction proteins that specifically inhibit the type I restriction-modification systems. Native Ocr forms homodimer (Ocr)2 both in solution and in the crystalline state. The Ocr protein belongs to the family of mimicry proteins. F53D A57E and E53R V77D mutant proteins were obtained, which form monomers. It was shown that the values of the dissociation constants Kd for Ocr, Ocr F53D A57E and Ocr F53RV77D proteins with EcoKI enzyme differ in 1000 times: Kd (Ocr) = 10(-10) M, Kd (Ocr F53D A57E and Ocr F53R V77D) = 10(-7) M. Antimodification activity of the Ocr monomeric forms is significantly reduced. We have shown, that Ocr dimeric form has fundamental importance for high inhibitory activity.
authors.forename: G B
authors.initials: GB
authors.lastname: Zavil'gelskiĭ
authors.forename: V Iu
authors.initials: VIu
authors.lastname: Kotova
mesh_terms: D019943:Amino Acid Substitution; D017123:Bacteriophage T7 / Q000235:genetics / Q000378:metabolism*; D004262:DNA Restriction Enzymes / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015280:DNA Restriction-Modification Enzymes / Q000235:genetics / Q000378:metabolism*; D048168:Escherichia coli K12 / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D020125:Mutation, Missense; D055503:Protein Multimerization; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D015280:DNA Restriction-Modification Enzymes; C440255:Ocr protein, bacteriophage T7; D014764:Viral Proteins; D004262:DNA Restriction Enzymes; C089629:endodeoxyribonuclease EcoKI