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PMID:12670970
Citation |
Vellani, TS and Myers, RS (2003) Bacteriophage SPP1 Chu is an alkaline exonuclease in the SynExo family of viral two-component recombinases. J. Bacteriol. 185:2465-74 |
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Abstract |
Many DNA viruses concatemerize their genomes as a prerequisite to packaging into capsids. Concatemerization arises from either replication or homologous recombination. Replication is already the target of many antiviral drugs, and viral recombinases are an attractive target for drug design, particularly for combination therapy with replication inhibitors, due to their important supporting role in viral growth. To dissect the molecular mechanisms of viral recombination, we and others previously identified a family of viral nucleases that comprise one component of a conserved, two-component viral recombination system. The nuclease component is related to the exonuclease of phage lambda and is common to viruses with linear double-stranded DNA genomes. To test the idea that these viruses have a common strategy for recombination and genome concatemerization, we isolated the previously uncharacterized 34.1 gene from Bacillus subtilis phage SPP1, expressed it in Escherichia coli, purified the protein, and determined its enzymatic properties. Like lambda exonuclease, Chu (the product of 34.1) forms an oligomer, is a processive alkaline exonuclease that digests linear double-stranded DNA in a Mg(2+)-dependent reaction, and shows a preference for 5'-phosphorylated DNA ends. A model for viral recombination, based on the phage lambda Red recombination system, is proposed. |
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Keywords |
5' Untranslated Regions; Bacillus Phages/enzymology; Bacillus Phages/growth & development; Bacillus subtilis; Cations, Divalent; Cloning, Molecular; DNA, Viral/biosynthesis; Escherichia coli/metabolism; Exonucleases/biosynthesis; Exonucleases/chemistry; Exonucleases/genetics; Hydrogen-Ion Concentration; Magnesium; Recombinant Proteins/biosynthesis; Recombination, Genetic; Substrate Specificity |
Significance
Annotations
Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
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GO:0004527: exonuclease activity |
ECO:0000314: |
F |
Figure 4: Fluorescent signal on dsDNA has a higher intensity than on ssDNA or on nucleotides. The decrease in fluorescent signal is indicative of DNA digestion. |
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Notes
See also
References
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