Exon structure conservation despite low sequence similarity: a relic of dramatic events in evolution?

Area of Science:

• Evolutionary biology
• Genomics
• Bioinformatics

Background:

• The evolutionary role of introns, non-coding DNA sequences, is not well understood.
• Complete eukaryotic genomes provide opportunities to study intron function.
• Gene structure, encompassing intron position, phase, and length, is a key feature of eukaryotic genes.

Purpose of the Study:

• To investigate the conservation of gene structure in homologous protein domains.
• To determine if gene structure conservation correlates with protein function or evolutionary relationships.
• To explore the potential of gene structure conservation for identifying remote protein homologues.

Main Methods:

• Comparative analysis of gene structures across homologous protein domains in eukaryotic genomes.
• Utilizing protein tertiary structure information for sequence alignment when sequence similarity is low.
• Examining the relationship between gene structure conservation and biological processes.

Main Results:

• Conserved gene structures were observed in certain extracellular-signalling and nuclear domains, even with low sequence similarity.
• Intracellular signalling modules generally showed limited gene structure conservation.
• Domains with conserved gene structures, like cytokines, were often involved in similar biological processes, e.g., immune response.

Conclusions:

• Gene structure conservation may serve as a historical record of significant evolutionary events, such as the emergence of the immune system.
• Conserved intron positions and lengths can facilitate the detection of novel, distantly related protein homologues.
• This approach can aid in constructing phylogenetic trees for proteins with limited sequence similarity.