Mammalian BEX, WEX and GASP genes: coding and non-coding chimaerism sustained by gene conversion events

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Genetics

Background:

• Understanding mammalian genome evolution requires identifying sequence innovations.
• Gene duplication is a major driver of genome evolution, but concerted evolution studies are limited.
• Previous research focused on protein-coding regions, overlooking other genomic elements.

Purpose of the Study:

• To investigate sequence innovations and concerted evolution in mammalian genomes.
• To identify conserved elements and evolutionary mechanisms in mammalian-specific genes.
• To explore the role of concerted evolution in generating gene diversity.

Main Methods:

• Analysis of mammalian-specific gene expansion on human chromosome Xq22.1.
• Identification of conserved sequence motifs in 5' UTRs.
• Investigation of gene conversion events and their impact on genomic regions.
• Examination of three protein families: BEX, WEX, and GASP.

Main Results:

• A mammalian-specific expansion of over 20 rapidly-evolving genes was identified on chromosome Xq22.1.
• Highly divergent protein-coding regions contrasted with a conserved motif in 5' UTRs.
• Concerted evolution, likely via gene conversion, generated chimeric genes with independent 5' UTR and coding region histories.
• Elevated G+C levels were observed in genomic regions affected by concerted evolution.
• These events involved genes from BEX, WEX, and GASP families, often brain-expressed and involved in signaling and apoptosis.

Conclusions:

• A common DNA motif in the 5' UTR exons of mammalian-specific genes was identified.
• This motif underwent concerted evolution independently of coding regions, forming chimeric genes.
• Findings highlight the importance of non-coding regulatory elements and their lineage-specific evolution in mammals.