Structural Features of DNA in tRNA Genes and Their Upstream Sequences

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• RNA polymerase III (Pol III) transcribes tRNA genes using type II promoters with internal control regions (Box A, Box B) recognized by TFIIIC.
• The 5'-flanking regions of tRNA genes are crucial for transcription regulation, though consensus sequences are not universally conserved.
• TATA-binding protein (TBP) is a universal eukaryotic transcription factor, with an ortholog present in archaea.

Purpose of the Study:

• To detect intragenic and extragenic Pol III promoter positions regulating tRNA gene transcription in eukaryotes and archaea.
• To analyze DNA properties in tRNA gene flanking regions across organisms with and without TBP.

Main Methods:

• Analysis of textual, structural, mechanical, and physicochemical DNA properties in tRNA gene regions.
• Utilized representative tRNA gene sets from 11 organisms obtained from the GtRNAdb database.
• Comparative analysis across bacteria, archaea, and eukaryotes.

Main Results:

• Identical consensus sequences and locations for A- and B-boxes were found in tRNA genes across all three domains (eukaryotes, archaea, bacteria).
• Significant variations in DNA structural and mechanical properties of 5'-flanking regions were observed between and within domains.
• Conserved TATA-binding protein (TBP) binding sites were identified only in *S. pombe* and *A. thaliana*.

Conclusions:

• While core tRNA promoter elements are conserved, the regulatory 5'-flanking regions exhibit substantial evolutionary divergence.
• The variability in flanking regions suggests diverse regulatory mechanisms for tRNA gene transcription across different life domains.
• The limited conservation of TBP binding sites indicates domain-specific roles or alternative recruitment strategies.