Mutational analysis of the herpes simplex virus trans-inducing factor Vmw65

Area of Science:

• Molecular Virology
• Gene Regulation
• Protein Structure-Function Analysis

Background:

• Vmw65 is a herpes simplex virus (HSV) protein crucial for activating viral immediate-early genes.
• Understanding Vmw65's structure-function relationship is key to deciphering viral gene expression control.

Purpose of the Study:

• To investigate the relationship between Vmw65's primary structure and its trans-activating function.
• To identify specific regions of Vmw65 essential for transcriptional activation.

Main Methods:

• Generated in-frame insertion, deletion, and nonsense mutations in the Vmw65 gene.
• Assessed trans-activation by transient transfection of Vero cells using a reporter gene (chloramphenicol acetyltransferase) linked to an HSV-1 immediate-early promoter.
• Performed in vivo competition studies with deletion mutants.

Main Results:

• A highly acidic region near the C-terminus of Vmw65 is essential for trans-activation.
• The overall structural integrity of Vmw65 is critical for its function.
• A small N-terminal region is dispensable for trans-activating activity.
• A domain between amino acids 141 and 185 may be involved in protein-protein interactions.

Conclusions:

• Specific structural features, particularly a C-terminal acidic region, are vital for Vmw65's transcriptional activation.
• Vmw65's functional domains can be mapped, revealing regions critical for activity and others that are not.
• The study provides insights into the molecular mechanisms of HSV immediate-early gene regulation.