Stability domains of actin genes and genomic evolution

TL;DR

This study investigates the stability domains of actin genes across diverse organisms, revealing conserved boundaries linked to early eukaryotic evolution and suggesting thermodynamic mechanisms for intron insertion.

Contribution

It provides the first analysis of stability domains in actin genes across multiple kingdoms, highlighting conserved features and proposing mechanisms for intron insertion.

Findings

Common stability boundaries across distant organisms

Boundaries often align with intron positions in vertebrates

Evidence of thermodynamic-driven intron insertion mechanisms

Abstract

In eukaryotic genes the protein coding sequence is split into several fragments, the exons, separated by non-coding DNA stretches, the introns. Prokaryotes do not have introns in their genome. We report the calculations of stability domains of actin genes for various organisms in the animal, plant and fungi kingdoms. Actin genes have been chosen because they have been highly conserved during evolution. In these genes all introns were removed so as to mimic ancient genes at the time of the early eukaryotic development, i.e. before introns insertion. Common stability boundaries are found in evolutionary distant organisms, which implies that these boundaries date from the early origin of eukaryotes. In general boundaries correspond with introns positions of vertebrates and other animals actins, but not much for plants and fungi. The sharpest boundary is found in a locus where fungi, algae and animals have introns in positions separated by one nucleotide only, which identifies a hot-spot for insertion. These results suggest that some introns may have been incorporated into the genomes through a thermodynamic driven mechanism, in agreement with previous observations on human genes. They also suggest a different mechanism for introns insertion in plants and animals.