Dissecting non-B DNA structural motifs in untranslated regions of eukaryotic genomes

The untranslated regions (UTRs) of genes significantly impact various biological processes, including transcription, posttranscriptional control, mRNA stability, localization, and translation efficiency. In functional areas of genomes, non-B DNA structures such as cruciform, curved, triplex, G-quadruplex, and Z-DNA structures are common and have an impact on cellular physiology. Although the role of these structures in cis-regulatory regions such as promoters is well established in eukaryotic genomes, their prevalence within UTRs across different eukaryotic classes has not been extensively documented. Our study investigated the prevalence of various non-B DNA motifs within the 5' and 3' UTRs across diverse eukaryotic species. Our comparative analysis encompassed the 5'-UTRs and 3'UTRs of 360 species representing diverse eukaryotic domains of life, including Arthropoda (Diptera, Hemiptera, and Hymenoptera), Chordata (Artiodactyla, Carnivora, Galliformes, Passeriformes, Primates, Rodentia, Squamata, Testudines), Magnoliophyta (Brassicales), Fabales (Poales), and Nematoda (Rhabditida), on the basis of datasets derived from the UTRdb. We observed that species belonging to taxonomic orders such as Rhabditida, Diptera, Brassicales, and Hemiptera present a prevalence of curved DNA motifs in their UTRs, whereas orders such as Testudines, Galliformes, and Rodentia present a preponderance of G-quadruplexes in both UTRs. The distribution of motifs is conserved across different taxonomic classes, although species-specific variations in motif preferences were also observed. Our research unequivocally illuminates the prevalence and potential functional implications of non-B DNA motifs, offering invaluable insights into the evolutionary and biological significance of these structures.