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Functional differences among the six Saccharomyces cerevisiae tRNATrp genes
1Department of Molecular Biology, University of Wyoming, Laramie 82071, USA.
Yeast (Chichester, England)
|December 10, 1997
Summary
Functional differences in Saccharomyces cerevisiae tRNATrp genes were identified using a UGA mutation suppression assay. Divergence in 5' flanking sequences, not 3' sequences, correlated with varying suppressor activity, impacting gene function.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Biology
Background:
- The Saccharomyces cerevisiae genome contains six functional tRNATrp genes, with identical coding and intervening sequences.
- Significant divergence exists in the 5' and 3' flanking sequences of these tRNATrp genes.
- Previous research indicated that multi-copy tRNATrp genes can suppress UGA mutations.
Purpose of the Study:
- To investigate functional differences among the six Saccharomyces cerevisiae tRNATrp genes.
- To determine if flanking sequence variations correlate with differences in suppressor activity.
- To identify which tRNATrp genes exhibit functional suppressor capabilities.
Main Methods:
- A functional assay utilizing suppression of UGA mutations (leu2-2 and his4-260) was employed.
- Six tRNATrp genes were cloned into multi-copy vectors and transformed into yeast.
- Suppressor activity was quantified by measuring growth rates in selective media.
Main Results:
- Two of the six tRNATrp clones showed no suppressor activity.
- Two clones exhibited weak suppression of the leu2-2 marker.
- Two clones effectively suppressed both leu2-2 and his4-260 markers, with significant growth rate differences observed.
Conclusions:
- Functional variations exist among the six Saccharomyces cerevisiae tRNATrp genes.
- The degree of suppressor activity correlates with divergence in the 5' flanking sequences.
- 5' flanking sequence divergence, rather than 3' flanking sequence divergence, is likely responsible for the observed functional differences.