| Analysis of spliceosomal proteins in Trypanosomatids reveals novel functions in mRNA processing. | |
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MedLine Citation:
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PMID: 20592024 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In trypanosomatids, all mRNAs are processed via trans-splicing, although cis-splicing also occurs. In trans-splicing, a common small exon, the spliced leader (SL), which is derived from a small SL RNA species, is added to all mRNAs. Sm and Lsm proteins are core proteins that bind to U snRNAs and are essential for both these splicing processes. In this study, SmD3- and Lsm3-associated complexes were purified to homogeneity from Leishmania tarentolae. The purified complexes were analyzed by mass spectrometry, and 54 and 39 proteins were purified from SmD3 and Lsm complexes, respectively. Interestingly, among the proteins purified from Lsm3, no mRNA degradation factors were detected, as in Lsm complexes from other eukaryotes. The U1A complex was purified and mass spectrometry analysis identified, in addition to U1 small nuclear ribonucleoprotein (snRNP) proteins, additional co-purified proteins, including the polyadenylation factor CPSF73. Defects observed in cells silenced for U1 snRNP proteins suggest that the U1 snRNP functions exclusively in cis-splicing, although U1A also participates in polyadenylation and affects trans-splicing. The study characterized several trypanosome-specific nuclear factors involved in snRNP biogenesis, whose function was elucidated in Trypanosoma brucei. Conserved factors, such as PRP19, which functions at the heart of every cis-spliceosome, also affect SL RNA modification; GEMIN2, a protein associated with SMN (survival of motor neurons) and implicated in selective association of U snRNA with core Sm proteins in trypanosomes, is a master regulator of snRNP assembly. This study demonstrates the existence of trypanosomatid-specific splicing factors but also that conserved snRNP proteins possess trypanosome-specific functions. |
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Authors:
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Itai Dov Tkacz; Sachin Kumar Gupta; Vadim Volkov; Mali Romano; Tomer Haham; Pawel Tulinski; Ilana Lebenthal; Shulamit Michaeli |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-06-30 |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 285 ISSN: 1083-351X ISO Abbreviation: J. Biol. Chem. Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-08-30 Completed Date: 2010-10-05 Revised Date: 2011-09-13 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: United States |
Other Details:
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Languages: eng Pagination: 27982-99 Citation Subset: IM |
Affiliation:
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Mina and Everard Goodman Faculty of Life Sciences and Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan 52900, Israel. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Biological Transport Cell Line Leishmania / cytology*, genetics* Mass Spectrometry Polyadenylation Protozoan Proteins / isolation & purification, metabolism* RNA Splicing RNA, Messenger / genetics, metabolism RNA, Small Nuclear / metabolism RNA, Spliced Leader / biosynthesis Ribonucleoproteins, Small Nuclear / metabolism Species Specificity Spliceosomes / metabolism* |
| Grant Support | |
ID/Acronym/Agency:
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//Howard Hughes Medical Institute |
| Chemical | |
Reg. No./Substance:
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0/Protozoan Proteins; 0/RNA, Messenger; 0/RNA, Small Nuclear; 0/RNA, Spliced Leader; 0/Ribonucleoproteins, Small Nuclear |
| Comments/Corrections | |
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