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Computational identification of putative programmed translational frameshift sites
Atul A Shah1, Michael C Giddings, Jasmin B Parvaz
1Department of Human Genetics, University of Utah, SLC, 84112-5330, USA.
Bioinformatics (Oxford, England)
|August 15, 2002
Summary
Statistical analysis reveals underrepresented nucleotide sequences in yeast genes are linked to programmed frameshifting. This finding suggests a mechanism for producing alternative protein products, impacting gene expression.
Area of Science:
- Computational Biology
- Genetics
- Molecular Biology
Background:
- Investigates the hypothesis that programmed frameshift sites are underrepresented in protein-coding sequences due to selective pressure.
- Focuses on identifying and analyzing nucleotide subsequences within the Saccharomyces cerevisiae (yeast) genome.
Purpose of the Study:
- To develop and apply a computational method for identifying underrepresented nucleotide sequences potentially involved in programmed frameshifting.
- To evaluate the distribution of 7-base oligonucleotides (heptanucleotides) in yeast protein-coding sequences.
Main Methods:
- Developed a computer program to compare observed nucleotide subsequence frequencies against those predicted by a zero-order Markov chain model.
- The model was based on codon bias within the analyzed sequences.
- Analyzed over 6000 putative protein-coding sequences from S. cerevisiae.
Main Results:
- Identified specific heptanucleotides, including CUU-AGG-C and CUU-AGU-U, as significantly underrepresented in yeast coding sequences.
- These underrepresented heptanucleotides are associated with programmed +1 translational frameshifts essential for producing specific yeast proteins (ABP140 and EST3).
- Laboratory experiments confirmed that other identified underrepresented heptanucleotides, such as GGU-CAG-A, also promote significant translational frameshifting.
Conclusions:
- Underrepresentation of specific nucleotide sequences in yeast genes correlates with programmed translational frameshifting.
- This suggests a potential mechanism for generating diverse protein products from a single gene.
- The findings imply that other underrepresented heptamers may also encode transframe products, broadening the understanding of gene expression regulation.