Trypanosoma bruceimitochondria contain RNA helicase activity
| Autor: | Andreas Missel, H. Ulrich Göringer |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Protein Denaturation
Hot Temperature Molecular Sequence Data Trypanosoma brucei brucei Biology Substrate Specificity chemistry.chemical_compound Adenosine Triphosphate parasitic diseases Gene expression Genetics Animals Magnesium Posttranscriptional RNA processing Guide RNA Messenger RNA Base Sequence Serine Endopeptidases RNA RNA Nucleotidyltransferases RNA Helicase A Mitochondria Kinetics Biochemistry chemistry RNA editing Nucleic Acid Conformation Thermodynamics RNA Editing Endopeptidase K RNA Helicases DNA |
| Zdroj: | Nucleic Acids Research. 22:4050-4056 |
| ISSN: | 1362-4962 0305-1048 |
| DOI: | 10.1093/nar/22.20.4050 |
| Popis: | Mitochondrial gene expression in kinetoplastid organisms such as Trypanosoma, Leishmania and Crithidia requires a posttranscriptional RNA processing event known as kRNA editing. During editing, uridine nucleotides get inserted and deleted into pre-mRNAs directed by small, metabolically stable RNAs, termed guide RNAs. Although the precise mechanism of the reaction is not understood, the accepted working model describes the formation of extended anti-parallel RNA helices between gRNA molecules with pre- and partially edited mRNAs as intermediates. These duplex structures must be separated to ensure the sequential action of multiple gRNAs in a 3' to 5' polarity on the mRNA molecule. In spite of this fact, no unwinding activity has heretofore been identified in kinetoplastid mitochondria. We report the characterisation of a RNA helicase activity within Trypanosoma brucei mitochondrial extracts. The activity unwinds 25- and 48 bp, tailed RNA duplex structures but fails to separate DNA strands. It can be destroyed by heat denaturation as well as by proteinase K treatment. The activity requires magnesium cations and acts in a NTP/dNTP dependent manner. Hydrolysis of a nucleoside triphosphate is required rather than mere NTP binding as deduced from a comparison of unwinding in the presence of ATP and AMP-PCP. RNA duplexes mimicking presumed kRNA editing intermediates are substrates of the unwinding activity and therefore, we address the possible involvement of a RNA helicase activity during kRNA editing. |
| Databáze: | OpenAIRE |
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