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RNaselll activation of bacteriophage lambda N synthesis.
L Kameyama1, L Fernandez, D L Court
1Molecular Control and Genetics Section, ABL-Basic Research Program, NCI/FCRDC, Frederick, Maryland 21702-1201.
Molecular Microbiology
|December 1, 1991
Summary
Bacteriophage lambda N protein levels are controlled by RNaseIII, an enzyme that processes RNA stem structures. This processing enhances N protein expression by improving ribosome binding to the N mRNA.
Area of Science:
- Molecular Biology
- Microbiology
- Genetics
Background:
- Bacteriophage lambda N protein is crucial for phage gene expression, regulating transcription elongation.
- N protein facilitates the expression of downstream phage genes by preventing premature transcription termination.
Purpose of the Study:
- To investigate the post-transcriptional regulation of bacteriophage lambda N protein synthesis.
- To elucidate the role of RNaseIII in modulating N protein levels.
Main Methods:
- Utilized N-lacZ gene fusions to quantify N protein expression levels.
- Compared N expression in cells with functional RNaseIII versus those deficient in RNaseIII.
- Analyzed RNA stem structures within the N-leader RNA sequence.
Main Results:
- Cells containing RNaseIII exhibited at least a fourfold increase in N expression compared to RNaseIII-deficient cells.
- RNaseIII was found to process a specific RNA stem structure in the N-leader RNA.
- Deletion of this stem structure increased N expression and abolished RNaseIII-mediated stimulation.
Conclusions:
- RNaseIII post-transcriptionally regulates bacteriophage lambda N protein synthesis by processing an inhibitory RNA stem structure.
- This stem structure, located near the ribosome binding site, normally hinders translation initiation.
- RNaseIII-mediated processing relieves this translational block, thereby enhancing N protein production.