Different Modes of Transactivation of Bacteriophage Mu Late Promoters by Transcription Factor C

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Bacteriophage Mu transactivator protein C regulates late gene expression.
• The activation mechanism at the mom promoter involves DNA unwinding, RNA polymerase (RNAP) recruitment, and promoter clearance.
• The activation mechanism for other late gene promoters (lys, I, P) by protein C is unknown.

Purpose of the Study:

• To elucidate the distinct mechanisms of bacteriophage Mu late gene transcription activation by protein C at different promoters.
• To investigate the role of protein C in RNAP interaction and initiation steps at lys, I, P, and mom promoters.

Main Methods:

• Promoter-polymerase interaction studies were conducted.
• Analysis focused on individual steps of transcription initiation: RNAP recruitment, closed complex formation, and isomerization to open complex.
• Comparative analysis of protein C's effect across all late gene promoters.

Main Results:

• Unlike the mom promoter, RNAP recruitment and closed complex formation at Plys, PI, and PP are independent of protein C.
• Protein C's activation role at Plys, PI, and PP occurs during the isomerization from closed to open complex.
• Protein C exhibits distinct activation mechanisms at the mom promoter (recruitment and escape) versus other late promoters (isomerization).

Conclusions:

• The common activator, protein C, employs different strategies to activate transcription at distinct bacteriophage Mu late gene promoters.
• Distinct activation mechanisms, involving promoter recruitment/escape or isomerization, are crucial for optimizing the expression of each late gene.