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An unusual cellular factor potentiates protein-DNA complex assembly between Oct-1 and Vmw65
1Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada.
The Journal of Biological Chemistry
|January 15, 1993
Summary
A novel stimulatory factor (SF) enhances herpes simplex virus trans-activator Vmw65 DNA binding complex formation. This heat-stable, carbohydrate-containing factor is crucial for potent viral gene transcription stimulation.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Herpes simplex virus trans-activator Vmw65 interacts with cellular factors Oct-1 and VCAF-1.
- This interaction forms a DNA binding complex that activates viral immediate-early gene transcription.
Purpose of the Study:
- To identify novel cellular factors involved in Vmw65-mediated transcriptional activation.
- To characterize a newly discovered factor that enhances Vmw65 DNA binding complex formation.
Main Methods:
- Mobility shift analysis using nuclear extracts and bacterially expressed proteins.
- Partial purification of the stimulatory factor (SF) from HeLa cell extracts.
- Biochemical characterization including molecular weight estimation, heat, protease, nuclease, and phospholipase resistance assays, and solvent extraction.
Main Results:
- A distinct HeLa cell factor, designated SF, was identified.
- SF significantly enhances the stability or formation of Vmw65-dependent complexes.
- SF has an apparent molecular weight of 1500-3000 Da and is resistant to various inactivation treatments.
- SF pretreatment with beta-glucuronidase did not abolish its stimulatory activity but altered complex mobility, suggesting a carbohydrate component.
Conclusions:
- SF is likely a component of the Vmw65-induced complex.
- SF's properties suggest it is a carbohydrate-containing molecule.
- SF plays a significant role in enhancing Vmw65-mediated transcriptional activation of viral genes.