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Sequence comparison of new prokaryotic and mitochondrial members of the polypeptide chain release factor family

H J Pel1, M Rep, L A Grivell

  • 1Department of Molecular Cell Biology, University of Amsterdam, The Netherlands.

Nucleic Acids Research
|September 11, 1992
PubMed

Insights

Researchers identified a bacterial-like release factor in mitochondria (mRF-1) and a similar protein in Bacillus subtilis (putative RF-2). These findings suggest a conserved autoregulation mechanism and a proposed five-domain model for release factor structure.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Mitochondrial release factor mRF-1 shares sequence similarity with bacterial release factors RF-1 and RF-2.
  • Database searches revealed homologous sequences in unassigned genomic reading frames of Escherichia coli and Bacillus subtilis.

Purpose of the Study:

  • To identify and characterize bacterial-like release factors in prokaryotes and mitochondria.
  • To investigate the autoregulation mechanism of bacterial release factor genes.
  • To propose a structural model for release factors.

Main Methods:

  • Gene cloning and sequencing of mitochondrial release factor mRF-1.
  • Database searching for homologous protein sequences.
  • Sequence comparison and identity analysis.
  • Comparative analysis of prokaryotic and mitochondrial release factor sequences.

Main Results:

  • The mitochondrial release factor mRF-1 shows high sequence similarity to bacterial RF-1 and RF-2.
  • A Bacillus subtilis genomic reading frame encodes a protein 47% identical to E. coli and Salmonella typhimurium RF-2, suggesting it is B. subtilis RF-2.
  • The expression of the B. subtilis RF-2 gene is likely autoregulated by a stop codon-dependent +1 frameshift, similar to E. coli and S. typhimurium RF-2.
  • A five-domain model for release factor structure is proposed based on sequence comparisons.

Conclusions:

  • Mitochondrial and bacterial release factors share evolutionary and structural similarities.
  • Autoregulation via frameshifting is a conserved mechanism in bacterial release factor gene expression.
  • The proposed five-domain model provides insights into the structure and potential functions of release factors.

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