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Structure of the yeast ribosomal 5 S RNA-binding protein YL3
1Department of Molecular Biology and Genetics, University of Guelph, Ontario, Canada.
Abstract:
A gene coding for the 5 S rRNA-binding protein (YL3) in yeast (Saccharomyces cerevisiae) was isolated using a polymerase chain reaction-amplified gene probe. The DNA sequence contains no introns and codes for a 297 amino acid (Mr = 33,741) protein. Although the protein is just 1 residue longer than in rat, unlike the high sequence homology in the 5 S rRNAs from the same organisms, only about 45% of the amino acid residues are conserved with surprisingly little homology in the carboxyl-terminal end. Nevertheless, comparative studies indicate that a number of structural features are conserved including small repeats in the primary structure and a number of helical estimates in the higher order structure. One of the sequence repeats also appears to be present in the carboxyl-terminal end of the eukaryotic transcription factor TFIIIA suggesting an evolutionary relationship in these 5 S RNA-binding proteins.
Insights
Researchers isolated the yeast 5 S ribosomal RNA (rRNA)-binding protein YL3 gene. Despite low sequence homology with rat, conserved structural features suggest an evolutionary link to transcription factor TFIIIA.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The 5 S ribosomal RNA (rRNA) is a crucial component of ribosomes.
- Proteins that bind to 5 S rRNA play vital roles in ribosome assembly and function.
- Understanding these proteins can provide insights into gene expression and evolution.
Purpose of the Study:
- To isolate and characterize the gene encoding the 5 S rRNA-binding protein (YL3) in yeast (Saccharomyces cerevisiae).
- To compare the deduced amino acid sequence and structural features of yeast YL3 with its mammalian counterparts.
- To investigate potential evolutionary relationships between 5 S rRNA-binding proteins.
Main Methods:
- Polymerase chain reaction (PCR) amplification using a gene probe.
- DNA sequencing to determine the gene structure and protein coding potential.
- Bioinformatic analysis for sequence homology and structural feature comparison.
Main Results:
- The yeast YL3 gene was isolated and found to contain no introns.
- The gene codes for a 297 amino acid protein with a molecular mass of 33,741 Da.
- While overall sequence homology with rat YL3 is moderate (~45%), conserved structural elements, including repeats and helical structures, were identified.
- A sequence repeat in YL3 is also present in the eukaryotic transcription factor TFIIIA.
Conclusions:
- The yeast YL3 protein shares conserved structural features with other 5 S rRNA-binding proteins despite variations in primary sequence.
- The presence of a shared sequence repeat suggests an evolutionary relationship between YL3 and transcription factor TFIIIA.
- These findings contribute to understanding the evolution of RNA-binding proteins involved in gene expression.