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The Autographa californica nuclear polyhedrosis virus p143 gene encodes a DNA helicase
1Departments of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 77843-2128, USA.
Abstract:
The P143 protein of Autographa californica nuclear polyhedrosis virus is essential for replication of viral DNA. To determine the function of P143, the protein was purified to near homogeneity from recombinant baculovirus-infected cells that overexpress P143. ATPase activity copurified with P143 protein during purification and also during gel filtration at a high salt concentration. The ATPase activity did not require the presence of single-stranded DNA, but was stimulated fourfold by the addition of single-stranded DNA. The ATPase activity of P143 had a K(m) of 60 microM and a turnover of 4.5 molecules of ATP hydrolyzed/s/molecule of enzyme, indicating moderate affinity for ATP and high catalytic efficiency. P143 unwound a 40-nucleotide primer in an ATP-dependent manner, indicating that the enzyme possesses in vitro DNA helicase activity. Based on this result, it seems likely that P143 functions as a helicase in viral DNA replication.
Insights
The Autographa californica nuclear polyhedrosis virus P143 protein functions as a DNA helicase. This essential viral protein unwinds DNA, crucial for viral DNA replication.
Area of Science:
- Molecular biology
- Virology
Background:
- The P143 protein is vital for Autographa californica nuclear polyhedrosis virus (AcNPV) DNA replication.
- Understanding P143's function is key to deciphering viral replication mechanisms.
Purpose of the Study:
- To elucidate the biochemical function of the AcNPV P143 protein.
- To investigate the enzymatic activities associated with P143.
Main Methods:
- Purification of P143 protein from recombinant baculovirus-infected cells.
- Assaying ATPase activity in the presence and absence of single-stranded DNA.
- DNA unwinding assays to assess helicase activity.
Main Results:
- ATPase activity was associated with purified P143 protein.
- The ATPase activity was stimulated by single-stranded DNA.
- P143 demonstrated ATP-dependent DNA helicase activity, unwinding a DNA substrate.
Conclusions:
- The P143 protein exhibits DNA helicase activity.
- P143 likely functions as a helicase in AcNPV DNA replication.