Document Detail

Differential functions of two editosome exoUases in Trypanosoma brucei.
MedLine Citation:
PMID:  19318463     Owner:  NLM     Status:  MEDLINE    
Mitochondrial RNAs in trypanosomes are edited by the insertion and deletion of uridine (U) nucleotides to form translatable mRNAs. Editing is catalyzed by three distinct editosomes that contain two related U-specific exonucleases (exoUases), KREX1 and KREX2, with the former present exclusively in KREN1 editosomes and the latter present in all editosomes. We show here that repression of KREX1 expression leads to a concomitant reduction of KREN1 in approximately 20S editosomes, whereas KREX2 repression results in reductions of KREPA2 and KREL1 in approximately 20S editosomes. Knockdown of KREX1 results in reduced cell viability, reduction of some edited RNA in vivo, and a significant reduction in deletion but not insertion endonuclease activity in vitro. In contrast, KREX2 knockdown does not affect cell growth or editing in vivo but results in modest reductions of both insertion and deletion endonuclease activities and a significant reduction of U removal in vitro. Simultaneous knockdown of both proteins leads to a more severe inhibition of cell growth and editing in vivo and an additive effect on endonuclease cleavage in vitro. Taken together, these results indicate that both KREX1 and KREX2 are important for retention of other proteins in editosomes, and suggest that the reduction in cell viability upon KREX1 knockdown is likely a consequence of KREN1 loss. Furthermore, although KREX2 appears dispensable for cell growth, the increased inhibition of editing and parasite viability upon knockdown of both KREX1 and KREX2 together suggests that both proteins have roles in editing.
Nancy Lewis Ernst; Brian Panicucci; Jason Carnes; Kenneth Stuart
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-03-24
Journal Detail:
Title:  RNA (New York, N.Y.)     Volume:  15     ISSN:  1469-9001     ISO Abbreviation:  RNA     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-04-16     Completed Date:  2009-05-08     Revised Date:  2013-06-02    
Medline Journal Info:
Nlm Unique ID:  9509184     Medline TA:  RNA     Country:  United States    
Other Details:
Languages:  eng     Pagination:  947-57     Citation Subset:  IM    
Seattle Biomedical Research Institute, Seattle, Washington 98109, USA.
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MeSH Terms
Exonucleases / metabolism*
Gene Knockdown Techniques
RNA Editing*
RNA Interference
Trypanosoma brucei brucei / enzymology*,  metabolism
Uridine / metabolism
Grant Support
Reg. No./Substance:
58-96-8/Uridine; EC 3.1.-/Exonucleases

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