A mutational analysis of DNA mimicry by ocr, the gene 0.3 antirestriction protein of bacteriophage T7

Augoustinos S. Stephanou, Gareth A. Roberts, Mark R. Tock, Emily H. Pritchard, Rachel Turkington, Margaret Nutley, Alan Cooper, David T. F. Dryden

Research output: Contribution to journalArticlepeer-review

Abstract

The ocr protein of bacteriophage T7 is a structural and electrostatic mimic of approximately 24 base pairs of double-stranded B-form DNA. As such, it inhibits all Type I restriction and modification (R/M) enzymes by blocking their DNA binding grooves and inactivates them. This allows the infection of the bacterial cell by T7 to proceed unhindered by the action of the R/M defence system. We have mutated aspartate and glutamate residues on the surface of ocr to investigate their contribution to the tight binding between the EcoKI Type I R/M enzyme and ocr. Contrary to expectations, all of the single and double site mutations of ocr constructed were active as anti-R/M proteins in vivo and in vitro indicating that the mimicry of DNA by ocr is very resistant to change. (C) 2008 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)129-132
Number of pages4
JournalBiochemical and Biophysical Research Communications
Volume378
Issue number1
DOIs
Publication statusPublished - 2 Jan 2009

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