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Mol. Cell. Biol., 09 1997, 4895-4903, Vol 17, No. 9
A Missel, AE Souza, G Norskau and HU Goringer
The majority of mitochondrial pre-mRNAs in kinetoplastid protozoa such as
Trypanosoma, Leishmania, and Crithidia are substrates of a
posttranscriptional processing reaction referred to as RNA editing. The
process results in the insertion and, to a lesser extent, deletion of
uridylates, thereby completing the informational content of the mRNAs. The
specificity of the RNA editing reaction is provided by guide RNAs (gRNAs),
which serve as templates for the editing apparatus. In addition, the
process relies on mitochondrial proteins, presumably acting within a
high-molecular-mass ribonucleoprotein complex. Although several enzymatic
activities have been implicated in the editing process, no protein has been
identified to date. Here we report the identification of a novel
mitochondrial DEAD-box protein, which we termed mHel61p. Disruption of the
mHEL61 alleles in insect-stage Trypanosoma brucei cells resulted in a
reduced growth rate phenotype. On a molecular level, the null mutant showed
significantly reduced amounts of edited mRNAs, whereas never-edited and
nuclear mRNAs were unaffected. Reexpression of mHel61p in the knockout cell
line restored the ability to efficiently synthesize edited mRNAs. The
results suggest an involvement of mHel61p in the control of the abundance
of edited mRNAs and thus reveal a novel function for DEAD-box proteins.
Copyright © 1997, American Society for Microbiology
Disruption of a gene encoding a novel mitochondrial DEAD-box protein in Trypanosoma brucei affects edited mRNAs
Laboratorium fur molekulare Biologie, Genzentrum der Ludwig-Maximilians- Universitat Munchen, Martinsried, Germany.
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