Structure and function of the Epstein-Barr virus BZLF1 protein

Area of Science:

• Virology
• Molecular Biology
• Epigenetics

Background:

• Epstein-Barr virus (EBV) is a human herpesvirus implicated in various cancers.
• The BZLF1 protein is a key viral transactivator essential for EBV lytic replication.
• Understanding EBV BZLF1 protein's DNA-binding and transcriptional regulation is crucial for therapeutic strategies.

Purpose of the Study:

• To identify and characterize the DNA-binding sites of the Epstein-Barr virus BZLF1 protein.
• To determine the specific regions of the BZLF1 protein involved in sequence-specific DNA binding.
• To elucidate the mechanism by which BZLF1 regulates viral transcription, potentially involving cellular factors.

Main Methods:

• Identification of DNA-binding sites within EBV early viral promoters using biochemical assays.
• Deletion mapping to pinpoint the DNA-binding domain of the BZLF1 protein.
• Site-directed mutagenesis of identified DNA target sites to assess binding and functional impact.

Main Results:

• Five distinct DNA-binding sites for the EBV BZLF1 protein were identified in three early viral promoters.
• Four of these identified binding sites contained a consensus AP-1 site.
• Deletion mapping identified the specific protein region responsible for sequence-specific DNA binding to an AP-1-like site.
• Mutagenesis studies suggested that BZLF1 might function by alleviating cellular repression of viral transcription.

Conclusions:

• The Epstein-Barr virus BZLF1 protein interacts with specific DNA sequences in viral promoters, notably AP-1 sites.
• The BZLF1 protein possesses a defined DNA-binding domain crucial for its function.
• BZLF1-mediated viral transcription activation may involve the disruption of cellular repressor activity.