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Interaction of rho factor with bacteriophage lambda cro gene transcripts
The Journal of Biological Chemistry
|August 5, 1985
Summary
Rho protein binds specifically to bacteriophage lambda cro mRNA transcripts. This binding is dependent on a 3' terminal segment with specific structural properties, crucial for transcription termination.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Rho protein is essential for transcription termination of the cro gene in bacteriophage lambda.
- Rho protein interacts with RNA during the termination process.
Purpose of the Study:
- To investigate the specificity and binding strength of Rho protein to isolated cro transcripts.
- To identify the structural features of cro RNA that mediate Rho binding.
Main Methods:
- Nitrocellulose filter retention assay was used to measure Rho-RNA binding.
- Association constants (K alpha) were determined for various cro RNA lengths and modifications.
Main Results:
- Rho protein exhibits a high affinity (K alpha = 7 +/- 2 X 10(8) M-1) for a 372-nucleotide cro transcript at 37°C.
- Binding affinity decreases for shorter transcripts (<290 nucleotides) and non-specific RNA.
- Binding is enhanced in cro transcripts where guanosine is replaced with inosine, suggesting a preference for regions with fewer guanosine residues.
Conclusions:
- Rho protein binding to lambda cro mRNA is dependent on a 3' terminal segment of at least 85 nucleotides with a low guanosine content (<14%).
- This segment is likely largely single-stranded, facilitating Rho interaction for transcription termination.