Poster Presentation 40th Annual Lorne Genome Conference 2019

Investigating the key mechanisms of alternative polyadenylation (#261)

Rachael E Turner 1 , Belinda J Goldie 1 , Paul F Harrison 2 , Melissa Curtis 1 , Bernhard Dichtl 3 , Traude H Beilharz 1
  1. Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC, Australia
  2. Monash Bioinformatics Platform, Monash University, Melbourne, VIC, Australia
  3. Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia

The 3’-untranslated region (3’-UTR) marks an important landscape for regulation of mRNA fate. Through the binding of key regulatory elements such as microRNAs and RNA binding proteins, the 3’-UTR can influence the stability, localisation and translatability of mRNA. In eukaryotes, up to 80% of genes regulate 3’-UTR length by encoding multiple locations for cleavage and polyadenylation (CPA) within the nascent transcript, a process known as alternative polyadenylation (APA). A naturally occurring adenosine analogue, cordycepin (3’-deoxyadenosine), is known to cause bulk mRNA shortening through chain termination due to its lack of a reactive hydroxyl group at the 3’ position. Using poly(A)-tail-focused deep sequencing, PAT-seq, we show that, unexpectedly, treatment with cordycepin induces bulk transcript lengthening and increased usage of distal CPA sites in yeast. A similar result was found for yeast strains with defective CPA machinery, implicating CPA complex stoichiometry as a key determinant of CPA site choice. Using yeast nucleosome occupancy data, we also show that genes that are able to undergo alternative polyadenylation have a wider nucleosome depleted region at the 3’-end of the gene suggesting that the higher ordering of the gene itself plays a significant role in CPA site usage.