Poster abstracts

Poster number 111 submitted by Clara Smoniewski

Roles of multiple polymerases in trypanosome mitochondrial non-encoded mRNA tail addition

Clara M. Smoniewski (Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus), Miranda Galey (Department of Biology, University of Minnesota Duluth), Marshall Hampton (Department of Mathematics and Statistics, University of Minnesota Duluth), Sara L. Zimmer (Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus)

Abstract:
Trypanosoma brucei is a parasitic protozoa that causes devastating vector-borne human and livestock diseases. The parasite modifies its metabolism to utilize different nutrients available in its insect vector and mammalian host, requiring extensive gene expression regulation, particularly in the mitochondria. In the trypanosome mitochondrion, gene expression is regulated post-transcriptionally because genes are polycistronically transcribed. Non-encoded 3' tails on trypanosome mitochondrial mRNAs have transcript and life-stage specific differences and are known to play a role in gene expression regulation. There are two types of heterogeneous A/U tails: initially added (in-tails), which are short and likely stability elements; and extended (ex-tails), which are longer and seem to have a role in translation. Our mathematical modeling of the distribution of As within the tails suggest that there may be multiple different ways that As are being added. This is consistent with two different poly(A) polymerases being active in the mitochondria: the primary polymerase kPAP1, and a putative polymerase kPAP2 that has been minimally characterized to date. By genetically manipulating these polymerases, we will investigate their effect on tail composition and length. A combination of hidden Markov modeling and genetic manipulations should clarify how the tails are differentially added to transcripts and across life-stages, and may lead to a greater understanding of the tails' roles in gene expression regulation.

Keywords: Post-transcriptional regulation, mitochondrial 3 non-encoded tails, trypanosomes