ICP35 Is a TREX-Like Protein Identified in White Spot Syndrome Virus

PLoS One. 2016 Jun 27;11(6):e0158301. doi: 10.1371/journal.pone.0158301. eCollection 2016.

Abstract

ICP35 is a non-structural protein from White spot syndrome virus believed to be important in viral replication. Since ICP35 was found to localize in the host nucleus, it has been speculated that the function of ICP35 might be involved in the interaction of DNA. In this study, we overexpressed, purified and characterized ICP35. The thioredoxin-fused ICP35 (thio-ICP35) was strongly expressed in E. coli and be able to form itself into dimers. Investigation of the interaction between ICP35 and DNA revealed that ICP35 can perform DNase activity. Structural model of ICP35 was successfully built on TREX1, suggesting that ICP35 might adopt the folding similar to that of TREX1 protein. Several residues important for dimerization in TREX1 are also conserved in ICP35. Residue Asn126 and Asp132, which are seen to be in close proximity to metal ions in the ICP35 model, were shown through site-directed mutagenesis to be critical for DNase activity.

MeSH terms

  • Cloning, Molecular
  • Enzyme Activation
  • Exodeoxyribonucleases
  • Gene Expression
  • Hydrogen Bonding
  • Models, Molecular
  • Mutagenesis
  • Phosphoproteins
  • Protein Conformation
  • Protein Multimerization
  • Recombinant Proteins
  • Viral Nonstructural Proteins / chemistry
  • Viral Nonstructural Proteins / genetics*
  • Viral Nonstructural Proteins / metabolism
  • White spot syndrome virus 1 / genetics*
  • White spot syndrome virus 1 / metabolism

Substances

  • Phosphoproteins
  • Recombinant Proteins
  • Viral Nonstructural Proteins
  • Exodeoxyribonucleases
  • three prime repair exonuclease 1

Grants and funding

This study was financially supported by National Research Council of Thailand (Grant No. 55000579 and 56000166). PP was funded by a scholarship from the Faculty of Science, KMUTT, Thailand. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.