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Processivity errors of gene expression in Escherichia coli

F Jørgensen1, C G Kurland

  • 1Department of Molecular Biology, University of Uppsala, Sweden.

Journal of Molecular Biology
|October 20, 1990
PubMed

Insights

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.

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