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Ambiguity in a polypeptide-synthesizing extract from Saccharomyces cerevisiae
Journal of Bacteriology
|July 1, 1973
Summary
Environmental factors like magnesium and spermine cause ambiguity in yeast protein synthesis, leading to incorrect amino acid incorporation. This suggests a similar ribosomal screening mechanism exists in yeast as in bacteria.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Environmental factors can influence protein synthesis accuracy.
- Bacterial systems exhibit ambiguity in polypeptide synthesis under certain conditions.
Purpose of the Study:
- To investigate environmental factors inducing translational ambiguity in yeast.
- To compare yeast and bacterial ribosomal mechanisms for fidelity.
Main Methods:
- In vitro cytoplasmic polypeptide synthesis using Saccharomyces cerevisiae.
- Polyuridylic acid-directed polypeptide synthesis.
- Kinetic studies and aminoacylation assays.
Main Results:
- Magnesium, spermine, and spermidine induced leucine-phenylalanine ambiguity.
- Isoleucine and serine incorporation also observed with magnesium and spermine.
- Lowering pH reduced ambiguity; ethanol and neomycin slightly enhanced it.
- Yeast ribosomal screening site proposed, similar to bacterial systems.
Conclusions:
- Yeast ribosomes possess a tRNA-screening site influencing translational fidelity.
- Environmental factors modulate this site, leading to ambiguous codon translation.
- Findings suggest conserved mechanisms for translational control across species.