TbMP42, a protein component of the RNA editing complex in African trypanosomes, has endo-exoribonuclease activity.

Michael Brecht, Moritz Niemann, Elke Schlüter, Ulrich F Müller, Ken Stuart, H Ulrich Göringer

Department of Microbiology and Genetics, Darmstadt University of Technology, Schnittspahnstrasse 10, 64287 Darmstadt, Germany.

Molecular cell 2005 Mar 4

filter terms:

RNA editing in trypanosomatids is catalyzed by a high molecular mass RNP complex, which is only partially characterized. TbMP42 is a 42 kDa protein of unknown function that copurifies with the editing complex. The polypeptide is characterized by two Zn fingers and a potential barrel structure/OB-fold at its C terminus. Using recombinant TbMP42, we show that the protein can bind to dsRNA and dsDNA but fails to recognize DNA/RNA hybrids. rTbMP42 degrades ssRNA by a 3' to 5' exoribonuclease activity. In addition, rTbMP42 has endoribonuclease activity, which preferentially hydrolyzes non-base-paired uridylate-containing sequences. Gene silencing of TbMP42 inhibits cell growth and is ultimately lethal to the parasite. Mitochondrial extracts from TbMP42-minus trypanosomes have only residual RNA editing activity and strongly reduced endo-exoribonuclease activity. However, all three activities can be restored by the addition of rTbMP42. Together, the data suggest that TbMP42 contributes both endo- and exoribonuclease activity to the editing reaction cycle.

Citation

Michael Brecht, Moritz Niemann, Elke Schlüter, Ulrich F Müller, Ken Stuart, H Ulrich Göringer. TbMP42, a protein component of the RNA editing complex in African trypanosomes, has endo-exoribonuclease activity. Molecular cell. 2005 Mar 4;17(5):621-30