Inhibition of the type I restriction-modification enzymes EcoB and EcoK by the gene 0.3 protein of bacteriophage T7
- PMID: 2989534
- DOI: 10.1016/0022-2836(85)90242-6
Inhibition of the type I restriction-modification enzymes EcoB and EcoK by the gene 0.3 protein of bacteriophage T7
Abstract
The gene 0.3 protein of bacteriophage T7 is a potent inhibitor of the restriction-modification enzymes EcoB and EcoK, both in vivo and in vitro. We have analyzed the ability of purified 0.3 protein to inhibit different steps in the reactions of EcoB and EcoK with DNA. Most of our experiments were done with EcoK, but selected tests with EcoB indicate that the two enzymes are affected by 0.3 protein in the same way. Purified 0.3 protein binds tightly to free enzyme, apparently to one of the small subunits, and prevents it from binding to DNA. If EcoK is allowed to form specific recognition complexes with unmodified DNA before 0.3 protein is added, relatively low levels of 0.3 protein prevent the nuclease activity that would otherwise appear upon addition of ATP, but considerably higher levels are needed to prevent formation of filter-binding complexes or ATPase activity. This, together with other results, suggests that the binding site for 0.3 protein is protected in recognition complexes and in the early stages of the ATP-stimulated reactions, but that it becomes accessible again before cleavage of the DNA, perhaps after the translocation step. If added after the nuclease reaction is substantially over, 0.3 protein has little effect on ATPase activity, and indeed, the subunit having the binding site for 0.3 protein apparently dissociates from the enzyme-DNA complex. The methylase activity of EcoK on hemi-methylated recognition sites is strongly inhibited by 0.3 protein added at any stage of the reaction.
Similar articles
-
Avoidance of DNA methylation. A virus-encoded methylase inhibitor and evidence for counterselection of methylase recognition sites in viral genomes.Cell Biophys. 1989 Aug-Oct;15(1-2):87-95. doi: 10.1007/BF02991582. Cell Biophys. 1989. PMID: 2476230 Review.
-
Entry of bacteriophage T7 DNA into the cell and escape from host restriction.J Bacteriol. 1988 May;170(5):2095-105. doi: 10.1128/jb.170.5.2095-2105.1988. J Bacteriol. 1988. PMID: 2834322 Free PMC article.
-
Model for how type I restriction enzymes select cleavage sites in DNA.Proc Natl Acad Sci U S A. 1988 Jul;85(13):4677-81. doi: 10.1073/pnas.85.13.4677. Proc Natl Acad Sci U S A. 1988. PMID: 2838843 Free PMC article.
-
[DNA methylation in T3 and T7 phages by DNA-adenine methylases of various types and methylase EcoK ocR+ by protein].Dokl Akad Nauk SSSR. 1983 Nov-Dec;273(1):234-7. Dokl Akad Nauk SSSR. 1983. PMID: 6581040 Russian. No abstract available.
-
[Antirestriction proteins ardA and Ocr as effective inhibitors of the type I restriction-modification enzymes].Mol Biol (Mosk). 2009 Mar-Apr;43(2):264-73. Mol Biol (Mosk). 2009. PMID: 19425495 Review. Russian.
Cited by
-
The phage-host arms race: shaping the evolution of microbes.Bioessays. 2011 Jan;33(1):43-51. doi: 10.1002/bies.201000071. Bioessays. 2011. PMID: 20979102 Free PMC article. Review.
-
Avoidance of DNA methylation. A virus-encoded methylase inhibitor and evidence for counterselection of methylase recognition sites in viral genomes.Cell Biophys. 1989 Aug-Oct;15(1-2):87-95. doi: 10.1007/BF02991582. Cell Biophys. 1989. PMID: 2476230 Review.
-
A motif conserved among the type I restriction-modification enzymes and antirestriction proteins: a possible basis for mechanism of action of plasmid-encoded antirestriction functions.Nucleic Acids Res. 1995 Mar 11;23(5):785-7. doi: 10.1093/nar/23.5.785. Nucleic Acids Res. 1995. PMID: 7708494 Free PMC article.
-
Entry of bacteriophage T7 DNA into the cell and escape from host restriction.J Bacteriol. 1988 May;170(5):2095-105. doi: 10.1128/jb.170.5.2095-2105.1988. J Bacteriol. 1988. PMID: 2834322 Free PMC article.
-
Nucleotide sequence and analysis of the coliphage T3 S-adenosylmethionine hydrolase gene and its surrounding ribonuclease III processing sites.Nucleic Acids Res. 1987 Jan 26;15(2):717-29. doi: 10.1093/nar/15.2.717. Nucleic Acids Res. 1987. PMID: 3547328 Free PMC article.
Publication types
MeSH terms
Substances
Grants and funding
LinkOut - more resources
Full Text Sources
Molecular Biology Databases