Trypanosoma brucei mitochondria contain RNA helicase activity
Abstract
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...Continue Reading
References
Vaccinia virus RNA helicase: an essential enzyme related to the DE-H family of RNA-dependent NTPases
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African Trypanosomiasis
African trypanosomiasis, also known as sleeping sickness, is an insect-borne parasitic disease of humans and other animals. It is caused by protozoa of the species Trypanosoma brucei and almost invariably progresses to death unless treated. Discover the latest research on African trypanosomiasis here.