Structural comparison of two yeast tRNA Glu 3 genes

Area of Science:

• Molecular Biology
• Genetics
• Yeast Genomics

Background:

• The study investigates a specific DNA fragment from yeast, designated pY 5, which is part of a larger cloned segment.
• This fragment contains a gene encoding glutamate tRNA (tRNA^Glu).

Purpose of the Study:

• To determine the DNA sequence of a 1.7 kb Pst fragment from yeast.
• To compare this sequence with other known yeast tRNA genes and investigate sequence homologies.
• To identify repetitive elements within the yeast genome.

Main Methods:

• DNA sequencing of the 1.7 kb Pst fragment.
• Sequence comparison analysis with existing yeast tRNA genes (tRNA^Glu and tRNA^Ser).
• Hybridization studies to detect genomic repetitions.

Main Results:

• The coding region of the yeast tRNA^Glu gene in the Pst fragment is identical to the tRNA^Glu 3 gene from pY 20.
• Significant sequence homologies were observed between the flanking regions of the pY 5 and pY 20 tRNA^Glu genes, and surprisingly, between the flanking regions of the pY 20 tRNA^Glu gene and a tRNA^Ser gene.
• Hybridization experiments confirmed that parts of the Pst fragment are repeated within the yeast genome.

Conclusions:

• Despite sequence variations in flanking regions, conserved structural features may exist in the 5'-flanking regions of yeast tRNA genes.
• Extensive sequence homologies suggest potential functional or evolutionary relationships between different tRNA genes and their surrounding DNA in yeast.
• The presence of repeated sequences within the yeast genome, as indicated by the Pst fragment, highlights the complex organization of the yeast genome.