Translation repression by an RNA polymerase elongation complex.

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Bacteriophage lambda N protein interacts with bacterial Nus proteins and the NUT site in the N gene transcript.
• This interaction forms a transcription antitermination complex with RNA polymerase (RNAP).
• The N protein bound at NUT also functions to repress its own translation.

Purpose of the Study:

• To investigate if N protein and NUT site-mediated translation repression is dependent on the formation of the antitermination complex.
• To determine the role of the N-modified RNAP transcription complex in N translation repression.

Main Methods:

• Mutational analysis of nus and nut sites to assess their impact on antitermination complex formation and N translation repression.
• In vitro transcription using T7 RNAP to study N translation repression in the absence of an effective antitermination complex.
• Investigating the effect of a mutant RNAP beta subunit and NusA overexpression on N-mediated translation repression.

Main Results:

• Mutations in nus and nut that destabilize the antitermination complex prevent N-mediated translation repression.
• Transcription by T7 RNAP, which fails to form an effective antitermination complex, eliminates N translation repression.
• A mutant RNAP beta subunit reduces N translation repression, an effect suppressed by NusA overexpression.

Conclusions:

• The N-modified RNAP transcription complex is essential for the repression of N protein translation.
• Antitermination complex formation is intrinsically linked to the regulation of N protein translation.