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UGA suppression by normal tRNA Trp in Escherichia coli: codon context effects
Nucleic Acids Research
|February 25, 1981
Summary
The nucleotide sequence following a UGA stop codon influences protein synthesis. An adjacent adenine residue allows readthrough, enabling the production of readthrough proteins in prokaryotic genes.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Gene expression relies on precise termination signals.
- Prokaryotic messenger RNAs (mRNAs) utilize UGA as a termination codon.
- Readthrough proteins are synthesized when termination signals are suppressed.
Purpose of the Study:
- To re-examine nucleotide sequences downstream of in-phase UGA termination codons in prokaryotic mRNAs.
- To investigate the role of the nucleotide adjacent to UGA in translational termination versus readthrough.
Main Methods:
- Analysis of nucleotide sequences in prokaryotic gene mRNAs.
- Comparison of sequences associated with normal termination versus readthrough events.
Main Results:
- An adenine (A) residue is consistently found adjacent to the 3' side of UGA in mRNAs coding for readthrough proteins.
- This readthrough is mediated by the suppression of UGA by normal Escherichia coli tRNA Trp.
- The presence of an adenine residue facilitates the UGA readthrough process.
Conclusions:
- The nucleotide following a UGA codon dictates its efficiency as a termination signal.
- An adenine residue at this position permits UGA readthrough, leading to the synthesis of readthrough proteins.
- This finding provides insight into the regulation of gene expression at the translational level.