Related Experiment Video
Updated: Jun 1, 2026

Overexpressing and Purifying a Toxic Nuclease from Escherichia coli
Published on: August 29, 2025
Characterization of Sulfolobus islandicus rod-shaped virus 2 gp19, a single-strand specific endonuclease
Andrew F Gardner1, David Prangishvili, William E Jack
1New England Biolabs, Inc., Ipswich, MA 01938, USA. gardner@neb.com
Abstract:
The hyperthermophilic Sulfolobus islandicus rod-shaped virus 2 (SIRV2) encodes a 25-kDa protein (SIRV2gp19) annotated as a hypothetical protein with sequence homology to the RecB nuclease superfamily. Even though SIRV2gp19 homologs are conserved throughout the rudivirus family and presumably play a role in the viral life cycle, SIRV2gp19 has not been functionally characterized. To define the minimal requirements for activity, SIRV2gp19 was purified and tested under varying conditions. SIRV2gp19 is a single-strand specific endonuclease that requires Mg(2+) for activity and is inactive on double-stranded DNA. A conserved aspartic acid in RecB nuclease superfamily Motif II (D89) is also essential for SIRV2gp19 activity and mutation to alanine (D89A) abolishes activity. Therefore, the SIRV2gp19 cleavage mechanism is similar to previously described RecB nucleases. Finally, SIRV2gp19 single-stranded DNA endonuclease activity could play a role in host chromosome degradation during SIRV2 lytic infection.
Related Concept Videos
Viruses of Archaea
Viruses with RNA Genomes
Size and Structure of Viral Genomes
Non-LTR Retrotransposons
DNA Bacteriophages
Leaky Scanning

