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Pore-Forming Cardiotoxin VVA2 (Volvatoxin A2) Variant I82E/L86K Is an Atypical Duplex-Specific Nuclease

Summary

Researchers discovered that a toxic protein from edible mushrooms called VVA2 has a hidden ability to cut double-stranded DNA. When modified to remove its toxic effects, this protein became a powerful DNA-cutting enzyme that works best at warm temperatures and requires specific metal ions to function. This discovery could have practical applications in DNA research and diagnostic testing.

Background

VVA2 is a cardiotoxic protein from the edible mushroom Volvariella volvacea with known hemolytic, neurotoxic, and pore-forming activities. The protein was previously characterized primarily for its membrane-disrupting properties. This study reports a novel nuclease activity in a VVA2 variant lacking oligomerization capacity.

Objective

To characterize the duplex-specific nuclease activity of the recombinant VVA2 I82E/L86K variant and elucidate its enzymatic properties, substrate specificity, optimal conditions, and molecular mechanism of DNA cleavage.

Results

Re-VVA2 I82E/L86K demonstrated enhanced duplex-specific nuclease activity compared to wild-type, converting supercoiled DNA to nicked and linear forms. The enzyme required Mg2+ or Mn2+ as cofactors, exhibited optimal activity at pH 6-9 and 55°C, and preferentially cleaved dG-dC-rich regions. Amino acid E111 was identified as critical for nuclease activity through metal ion interaction.

Conclusion

VVA2 I82E/L86K represents an atypical duplex-specific nuclease with a novel non-conserved nuclease structure and a proposed double-hit cleavage mechanism. The findings suggest potential applications in cDNA library construction, molecular diagnostics, and RNA sequencing.
  • Published in:Toxins (Basel),
  • Study Type:Experimental Study,
  • Source: PMID: 35737053
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