Biochemical Characterization of a Structure-Specific Resolving Enzyme from Sulfolobus islandicus Rod-Shaped Virus 2

New England Biolabs, Inc., Ipswich, Massachusetts, United States of America.
PLoS ONE (Impact Factor: 3.23). 08/2011; 6(8):e23668. DOI: 10.1371/journal.pone.0023668
Source: PubMed


Sulfolobus islandicus rod shaped virus 2 (SIRV2) infects the archaeon Sulfolobus islandicus at extreme temperature (70°C-80°C) and acidity (pH 3). SIRV2 encodes a Holliday junction resolving enzyme (SIRV2 Hjr) that has been proposed as a key enzyme in SIRV2 genome replication. The molecular mechanism for SIRV2 Hjr four-way junction cleavage bias, minimal requirements for four-way junction cleavage, and substrate specificity were determined. SIRV2 Hjr cleaves four-way DNA junctions with a preference for cleavage of exchange strand pairs, in contrast to host-derived resolving enzymes, suggesting fundamental differences in substrate recognition and cleavage among closely related Sulfolobus resolving enzymes. Unlike other viral resolving enzymes, such as T4 endonuclease VII or T7 endonuclease I, that cleave branched DNA replication intermediates, SIRV2 Hjr cleavage is specific to four-way DNA junctions and inactive on other branched DNA molecules. In addition, a specific interaction was detected between SIRV2 Hjr and the SIRV2 virion body coat protein (SIRV2gp26). Based on this observation, a model is proposed linking SIRV2 Hjr genome resolution to viral particle assembly.

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Available from: William E Jack
    • "gp16, belonging to the replication initiator (Rep) family and nicking one strand of the viral genomic termini, was proposed to be involved in the initiation of the DNA replication [19]. The Holiday junction resolving enzyme (Hjr) gp35 was suggested to resolve the concatemers of the replicative intermediates, producing monomeric copies with linear hairpin ends [20]. Taken together, the functions of many SIRV2 genes remain unknown and the knowledge of its biology and basic molecular processes such as DNA replication, recombination and maturation is still limited. "
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