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GTP hydrolysis by eRF3 facilitates stop codon decoding during eukaryotic translation termination.
Joe Salas-Marco1, David M Bedwell
1Department of Microbiology, BBRB 432/Box 8, 1530 Third Ave. South, University of Alabama at Birmingham, Birmingham, AL 35294-2170, USA.
Molecular and Cellular Biology
|August 18, 2004
Summary
GTP hydrolysis by eukaryotic release factor 3 (eRF3) is crucial for efficient translation termination. Impaired GTP hydrolysis in yeast (Saccharomyces cerevisiae) selectively reduced termination efficiency at specific stop signals, highlighting eRF3
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Translation termination in eukaryotes involves release factors eRF1 and eRF3.
- eRF1 recognizes stop codons, while eRF3 (a GTPase) stimulates termination via an unclear mechanism.
Purpose of the Study:
- Investigate the role of GTP hydrolysis by eRF3 in Saccharomyces cerevisiae.
- Determine how eRF3's GTPase activity influences translation termination efficiency.
Main Methods:
- Created yeast mutants with reduced GTP hydrolysis rates for eRF3.
- Manipulated eRF1 and eRF3 levels using the CUP1 promoter.
- Assessed translation termination efficiency at various stop signals.
Main Results:
- Mutations reducing eRF3 GTP hydrolysis decreased termination efficiency at specific tetranucleotide signals (up to 17-fold).
- Limiting eRF1 or eRF3 levels caused a general decrease in termination efficiency, unlike the specific effect of eRF3 GTPase mutants.
- Overproducing eRF1 did not enhance termination efficiency.
Conclusions:
- GTPase activity of eRF3 is essential for coupling stop codon recognition by eRF1 to efficient polypeptide release.
- eRF3's GTP hydrolysis specifically regulates termination at certain signals, suggesting a distinct regulatory role beyond general factor availability.