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Interactions between human cytomegalovirus helicase-primase proteins
Timothy P McMahon1, David G Anders
1Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY 12201-2002, USA.
Virus Research
|June 22, 2002
Summary
Human cytomegalovirus (HCMV) proteins UL70, UL102, and UL105 form a three-protein complex essential for viral DNA replication. This study confirms their physical interactions, revealing each protein contacts the other two partners.
Area of Science:
- Virology
- Molecular Biology
- Protein Interactions
Background:
- Human cytomegalovirus (HCMV) encodes essential proteins UL70, UL102, and UL105, predicted to form the viral helicase-primase complex.
- These proteins are crucial for viral DNA synthesis, but their physical interactions and biochemical activities remain largely uncharacterized due to restricted expression.
Purpose of the Study:
- To investigate the physical interactions and assembly of the predicted HCMV helicase-primase complex.
- To determine if UL70, UL102, and UL105 proteins form a heteromeric complex and identify pairwise interactions.
Main Methods:
- Expression of untagged and glutathione-S-transferase (GST)-tagged UL70, UL102, and UL105 proteins using Semliki Forest Virus (SFV) vectors.
- Co-purification using GST-pull down assays with infected baby hamster kidney (BHK-21) cells.
- Immunoprecipitation experiments with untagged SFV-expressed proteins.
Main Results:
- UL70 and UL105 proteins co-purified with GST-UL102, indicating complex formation.
- Immunoprecipitation revealed pairwise interactions: pUL70/pUL102, pUL70/pUL105, and pUL102/pUL105.
- The N-terminal GST-tag was observed to interfere with specific pairwise protein interactions.
Conclusions:
- The findings support the prediction that HCMV UL70, UL102, and UL105 proteins assemble into a three-protein heteromeric complex.
- Each protein within the helicase-primase complex directly interacts with both of its partners, highlighting the intricate assembly of this essential viral machinery.
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