Recognition, variability and regulation of 5´ splicing sites

YANOVSKY MARCELO; BECKEL, MAXIMILIANO SEBASTIAN; CHERNOMORETZ ARIEL; RABINOVICH ANDRÉS

CABA

Simposio; Simposio Fronteras en Biociencias 3; 2018

Instituto Max Planck Argentina Instituto de Investigación en Biomedicina de Buenos Aires - CONICET - Instituto Partner de la Sociedad Max Planck

Recognition of splice sites is one of the first and most important steps in the splicing process, being affected by several regulatory pathways. Even though splice sites present a consensus sequence, sequence variability usually related to site strength exists. This recognition depends on a lot of different factors, such as enviromental conditions and cis and trans-acting elements. In this work we analysed more than 300,000 5´ splice site (5ss) sequences annotated in A. thaliana genome and developed a model that takes into account position frecuency and pairwise correlations between positions in the sequence. This model allowed us to caracterize 5ss strength from its sequence and study the biological role of splice site sequence variability. It was observed that mutations in PRMT5 (Protein arginin metiltransferases 5) affect weak 5ss recognition. In order to understand the relation between site strength, sequence variability and PRTM5 regulatory role, we used RNA-Seq to analyse the effects of PRMT5 mutation on two different A. thaliana accessions, Col-0 and Ler-1. We studied splicing events that were differentially expressed in the interaction between this two factors. On those events with a single nucleotide polymorphism (SNP) on the 5ss, a lower site recognition rate on the accession with a weaker site in PRMT5 mutant compared to the accession with a stronger site was observer. On the other hand, we also analyzed for this events the effects of PRTM5 mutation on Col-0 x Ler-1 hybrids. We found a larger intron retention rate and a lower weak site recognition rate. The interaction analysis would indicate that PRMT5 could help the splicing machinery to recognize weak splice sites. On the other hand, results obtained with the hybrid analysis restrict the effects of PRMT5 to a cis recognition site effect.