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Mutants of translational components that alter reading frame by two steps forward or one step back
M B Falahee1, R B Weiss, M O'Connor
1Howard Hughes Medical Institute, University of Utah, Salt Lake City 84132.
The Journal of Biological Chemistry
|December 5, 1988
Summary
External suppressors like sufS, hopR, and hopE can alter ribosomal frameshifting during protein synthesis. These suppressors cause ribosomes to shift reading frames, resulting in different amino acid sequences than initially encoded.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Ribosomal frameshifting is a mechanism that alters gene expression by causing the ribosome to shift its reading frame.
- Understanding frameshifting is crucial for comprehending gene expression regulation and potential therapeutic targets.
Purpose of the Study:
- To investigate the function of external suppressors sufS, hopR, and hopE in a -1 frameshift mutant.
- To elucidate the mechanism by which these suppressors alter ribosomal reading frames and amino acid incorporation.
Main Methods:
- Analysis of a -1 frameshift mutant in the presence of external suppressors.
- Determination of the amino acid sequence of the resulting polypeptide.
- Investigation of ribosome behavior at specific mRNA sequences.
Main Results:
- The suppressor sufS caused ribosomes to shift into the -1 frame at the sequence CAG GGA GUG, resulting in Gln-Gly-Ser instead of Gln-Gly-Val.
- The alleles investigated showed approximately 2% efficiency in causing frameshifting.
- Suppressors hopR and hopE allowed ribosomes to decode a single amino acid, Val, from the five nucleotides GUG UG.
Conclusions:
- External suppressors can effectively alter programmed ribosomal frameshifting.
- The suppressors hopR and hopE may act by facilitating peptidyl-tRNA(Val) dissociation and re-pairing after mRNA slippage.