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Processivity errors of gene expression in Escherichia coli
1Department of Molecular Biology, University of Uppsala, Sweden.
Journal of Molecular Biology
|October 20, 1990
Summary
Ribosomes have a 76% chance of completing protein synthesis, with 24% ending prematurely. A hyperaccurate mutant
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Ribosomes initiate but do not always complete mRNA translation, leading to truncated proteins.
- Understanding translation termination is crucial for protein synthesis fidelity and cellular function.
Purpose of the Study:
- To quantify the processivity of wild-type and mutant ribosomes during protein synthesis.
- To investigate the impact of streptomycin on ribosome processivity and accuracy.
- To identify factors contributing to premature translation termination.
Main Methods:
- Quantified lacZ monomer and dimer protein expression from a plasmid.
- Calculated the dimer to monomer ratio to determine ribosome processivity.
- Assessed the effect of streptomycin on a hyperaccurate mutant (SmP).
Main Results:
- Wild-type ribosomes exhibit a 76% completion rate for beta-galactosidase synthesis.
- Premature RNA polymerase termination accounts for approximately one-third of translation errors.
- The SmP mutant shows reduced processivity (0.28), which improves to 0.50 with streptomycin.
Conclusions:
- Ribosome hyperaccuracy in the SmP mutant is linked to decreased translation processivity.
- Streptomycin modulates ribosome function, decreasing one error class while increasing another.
- Findings are relevant for optimizing ribosome function and understanding mutant growth.