Related Experiment Videos
The actin gene in yeast Saccharomyces cerevisiae: 5' and 3' end mapping, flanking and putative regulatory sequences
Abstract:
The 5' and 3' flanking regions of the yeast actin gene have been sequenced and the ends of the actin mRNA were determined by the single-strand nuclease mapping procedure. The mRNA starts with a pyrimidine residue 141 (or 140) nucleotides upstream from the initiation codon. The actin gene lacks a typical "TATA" box 30 base pairs upstream from the mRNA start site but it contains a region homologous to the canonical sequence 5'-GGCTCAATCT-3' which is found in several eukaryotic genes 70 to 80 bp upstream from the mRNA cap site. Judging from the S1 nuclease mapping, there are two populations of actin mRNA terminating 98 and 107 nucleotides downstream from the stop codon. The 3' termini are preceded by three AATAAA sequences found in most eukaryotic polyadenylated mRNAs.
Insights
Researchers sequenced yeast actin gene flanking regions and mapped mRNA ends. They identified the mRNA start site and two distinct mRNA termination sites, with AATAAA sequences preceding the 3' termini.
Area of Science:
- Molecular Biology
- Yeast Genetics
Background:
- The yeast actin gene is essential for cellular structure and function.
- Understanding gene regulation, including mRNA processing, is crucial in molecular biology.
Purpose of the Study:
- To sequence the 5' and 3' flanking regions of the yeast actin gene.
- To precisely determine the start and end points of yeast actin mRNA.
- To investigate regulatory sequences involved in yeast actin gene expression.
Main Methods:
- DNA sequencing of flanking regions.
- Single-strand nuclease mapping (S1 nuclease mapping) to identify mRNA termini.
- Sequence analysis to identify conserved regulatory elements.
Main Results:
- The mRNA start site was mapped to a pyrimidine residue 140-141 nucleotides upstream of the initiation codon.
- A canonical TATA box was absent, but a homologous sequence (5"-GGCTCAATCT-3") was found 70-80 bp upstream of the cap site.
- Two populations of actin mRNA were identified, terminating 98 and 107 nucleotides downstream from the stop codon.
- Three AATAAA sequences, common in eukaryotic polyadenylated mRNAs, were found preceding the 3' termini.
Conclusions:
- The study precisely defined the boundaries of yeast actin mRNA.
- Non-canonical regulatory elements may be involved in yeast actin gene transcription initiation.
- Multiple polyadenylation signals contribute to the generation of mature actin mRNA in yeast.