Journal
MOLECULAR AND CELLULAR BIOLOGY
Volume 24, Issue 23, Pages 10390-10396Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/MCB.24.23.10390-10396.2004
Keywords
-
Categories
Funding
- NIAID NIH HHS [AI 056034, 2-T32-AI-07323, T32 AI007323, R01 AI056034] Funding Source: Medline
Ask authors/readers for more resources
In all trypanosomatids, trans splicing of the spliced leader (SL) RNA is a required step in the maturation of all nucleus-derived mRNAs. The SL RNA is transcribed with an oligo-U 3' extension that is removed prior to trans splicing. Here we report the identification and characterization of a nonexosomal, 3'-->5' exonuclease required for SL RNA 3'-end formation in Trypanosoma brucei. We named this enzyme SNIP (for snRNA incomplete 3' processing). The central 158-amino-acid domain of SNIP is related to the exonuclease III (ExoIII) domain of the 3'-->5' proofreading F subunit of Escherichia coli DNA pollymerase III holoenzyme. SNIP had a preference for oligo(U) 3' extensions in vitro. RNA interference-mediated knockdown of SNIP resulted in a growth defect and correlated with the accumulation of one- to two- nucleotide 3' extensions of SL RNA, U2 and U4 snRNAs, a five-nucleotide extension of 5S rRNA, and the destabilization of U3 snoRNA and U2 snRNA. SNIP-green fluorescent protein localized to the nucleoplasm, and substrate SL RNA derived from SNIP knockdown cells showed wild-type cap 4 modification, indicating that SNIP acts on SL RNA after cytosolic trafficking. Since the primary SL RNA transcript was not the accumulating species in SNIP knockdown cells, SL RNA X-end formation is a multistep process in which SNIP provides the ultimate X-end polishing. We speculate that SNIP is part of an organized nucleoplasmic machinery responsible for processing of SL RNA.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available