The two eIF4A helicases in Trypanosoma brucei are functionally distinct
| Autor: | Rodolfo Katz, Nina Marinsek, Rafael Dhalia, Osvaldo P. de Melo Neto, João R. C. Muniz, Christian R. S. Reis, Mark Carrington, Nancy Standart |
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| Přispěvatelé: | Standart, Nancy [0000-0001-5963-6255], Carrington, Mark [0000-0002-6435-7266], Apollo - University of Cambridge Repository |
| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular NONSENSE-MEDIATED DECAY INDUCIBLE EXPRESSION SYSTEM Molecular Sequence Data Trypanosoma brucei brucei mammalian-cells Protozoan Proteins Biology Article 03 medical and health sciences Transcription (biology) Genetics Protein biosynthesis Animals Amino Acid Sequence RNA Messenger 030304 developmental biology 0303 health sciences Messenger RNA MESSENGER-RNA DECAY Sequence Homology Amino Acid 030302 biochemistry & molecular biology crystal-structure RNA EXON JUNCTION COMPLEX RNA Helicase A Molecular biology EUKARYOTIC TRANSLATION INITIATION 3. Good health Isoenzymes DEAD-BOX PROTEIN Amino Acid Substitution eIF4A Eukaryotic Initiation Factor-4A Mutation saccharomyces-cerevisiae FACTOR 4A Exon junction complex RNA Interference Translation initiation complex |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| DOI: | 10.1093/nar/gkl290 |
| Popis: | Protozoan parasites belonging to the family Trypanosomatidae are characterized by an unusual pathway for the production of mRNAs via polycistronic transcription and trans-splicing of a 5' capped mini-exon which is linked to the 3' cleavage and polyadenylation of the upstream transcript. However, little is known of the mechanism of protein synthesis in these organisms, despite their importance as agents of a number of human diseases. Here we have investigated the role of two Trypanosoma brucei homologues of the translation initiation factor eIF4A (in the light of subsequent experiments these were named as TbEIF4AI and TbEIF4AIII). eIF4A, a DEAD-box RNA helicase, is a subunit of the translation initiation complex eIF4F which binds to the cap structure of eukaryotic mRNA and recruits the small ribosomal subunit. TbEIF4AI is a very abundant predominantly cytoplasmic protein (over 1 x 10(5) molecules/cell) and depletion to approximately 10% of normal levels through RNA interference dramatically reduces protein synthesis one cell cycle following double-stranded RNA induction and stops cell proliferation. In contrast, TbEIF4AIII is a nuclear, moderately expressed protein (approximately 1-2 x 10(4) molecules/cell), and its depletion stops cellular proliferation after approximately four cell cycles. Ectopic expression of a dominant negative mutant of TbEIF4AI, but not of TbEIF4AIII, induced a slow growth phenotype in transfected cells. Overall, our results suggest that only TbEIF4AI is involved in protein synthesis while the properties and sequence of TbEIF4AIII indicate that it may be the orthologue of eIF4AIII, a component of the exon junction complex in mammalian cells. |
| Databáze: | OpenAIRE |
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