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

TitleA mutational analysis of DNA mimicry by ocr, the gene 0.3 antirestriction protein of bacteriophage T7.
Publication TypeJournal Article
Year of Publication2009
AuthorsStephanou AS, Roberts GA, Tock MR, Pritchard EH, Turkington R, Nutley M, Cooper A, Dryden DTF
JournalBiochem Biophys Res Commun
Volume378
Issue1
Pagination129-32
Date Published2009 Jan 2
ISSN1090-2104
KeywordsAmino Acid Sequence, Bacteriophage T7, Dimerization, DNA Mutational Analysis, DNA Restriction Enzymes, Escherichia coli, Molecular Mimicry, Molecular Sequence Data, Protein Structure, Secondary, Viral Proteins
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.

DOI10.1016/j.bbrc.2008.11.014
Alternate JournalBiochem. Biophys. Res. Commun.
PubMed ID19013430
Grant List15/17860 / / Biotechnology and Biological Sciences Research Council / United Kingdom
GR080463MA / / Wellcome Trust / United Kingdom
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