Antirestriction activity of the monomeric and dimeric forms of T7 Ocr

作者：Zavilgelsky G B^*; Kotova V Yu

来源：Molecular Biology, 2014, 48(1): 150-157.

DOI：10.1134/S0026893313060174

• type I restriction-modification enzymes
• antirestriction proteins
• phage T7
• Ocr

The Ocr antirestriction protein, which is encoded by bacteriophage T7 0.3 (ocr), specifically inhibits type I restriction-modification enzymes. Ocr belongs to a family of DNA-mimicking proteins. Native Ocr forms homodimers both in solution and in crystal. Ocr mutants with two amino acid substitutions (Orc F53D A57E and Ocr F53R V77D) were constructed to occur as monomers in solution. The dissociation constant K (d) for the Ocr complex with EcoKI (R2M2S) proved to differ by three orders of magnitude between the (Ocr)(2) dimer and Ocr F53D A57E and Ocr F53R V77D monomers (10(-10) M vs. 10(-7) M). Antimodification activity was substantially lower in the Ocr monomers. The dimeric form found to be essential for high inhibitory activity of Ocr.

• 出版日期2014-1