Talk abstracts

Talk on Friday 07:50-08:10pm submitted by Kirk Gaston

C to U Editing at Position 32 of the Anticodon Loop Precedes tRNA 5' Leader Removal in Trypanosomatids

Kirk W. Gaston (Microbiology, The Ohio State University), Mary-Anne T. Rubio, Jessica L. Spears (Microbiology, The Ohio State University), Irena Pastar , F. Nina Papvasiliou (Laboratory of Lymphocyte Biology, Rockefeller University), Juan D. Alfonzo (Microbiology, The Ohio State University)

Abstract:
In all organisms precursor tRNAs are processed into mature functional units by post-transcriptional changes. These involve 5’ and 3’ end trimming as well as the addition of a significant number of chemical modifications, including RNA editing. The only known example of non-organellar C to U editing of tRNAs occurs in trypanosomatids. In this system, editing at position 32 of the anticodon loop of tRNAThr(AGU) stimulates, but is not required for, the subsequent formation of inosine at position 34. In the present work we expand the number of C to U edited tRNAs to include all the threonyl tRNA isoacceptors. Notably, the absence of a naturally encoded adenosine, at position 34, in two of these isoacceptors demonstrates that A to I is not required for C to U editing. We also show that C to U editing is a nuclear event while A to I is cytoplasmic, where C to U editing at position 32 occurs in the precursor tRNA prior to 5\' leader removal. Our data supports the view that C to U editing is more widespread than previously thought and is part of a stepwise process in the maturation of tRNAs in these organisms.

Keywords: editing, deamination, tRNA