Nucleic Acids Research Advance Access originally published online on October 4, 2007
Nucleic Acids Research 2007 35(20):6740-6749; doi:10.1093/nar/gkm745
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Nucleic Acids Research, 2007, Vol. 35, No. 20 6740-6749
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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C to U editing at position 32 of the anticodon loop precedes tRNA 5' leader removal in trypanosomatids
1Department of Microbiology, 2The Ohio State RNA Group, The Ohio State University, Columbus, Ohio 43210, and 3Laboratory of Lymphocyte Biology, The Rockefeller University, New York, NY 10021, USA
*To whom correspondence should be addressed. Tel: (614) 292 0004; Fax: (614) 292 8120; Email: alfonzo.1{at}osu.edu
Received July 17, 2007. Revised September 2, 2007. Accepted September 9, 2007.
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.