Evolution of RNA Polyadenylation Sites

RNA polyadenylation, poly(A), is an essential process for the expression of most genes. Knowledge about RNA poly(A) sites can assist gene design, allele identification, gene expression regulation, and genetic engineering. Most studies of poly(A) sites focused on one or a few species. We identified poly(A) site patterns after mapping RNA sequences to their corresponding reference genomes in microorganisms, plants, and animals. The poly(A) site is usually an adenosine, in nearly all the analyzed species. The poly(A) signal motifs are different in different groups of species: UUACUU in Trypanosoma cruzi (a parasite); UGUAAC in the alga Chlamydomonas reinhardtii; UGUUUG (or UGUUUGUU) in Blastocystis hominis (a parasite); and AAUAAA in all the analyzed animals and various plants. The most predominant poly(A) signal motif of a species can be located downstream of, directly on, or upstream of the poly(A) site, depending on the species. Fungi, animals, plants, and the potato late blight pathogen Phytophthora infestans were found to have a highly similar base abundance pattern: U-rich, A-rich, U-rich, poly(A) site, U-rich regions (or U-A-U-A-U for short) in the order from upstream to downstream of the poly(A) site. This presentation will compare the characteristics of poly(A) signal motifs, motif locations, and base composition patterns around mRNA poly(A) sites in protists, fungi, plants, and animals and will discuss the evolution of RNA poly(A) sites.