Is the Trypanosoma brucei REL1 RNA ligase specific for U-deletion RNA editing, and is the REL2 RNA ligase specific for U-insertion editing?
It was shown previously that the REL1 mitochondrial RNA ligase in Trypanosoma brucei was a vital gene and disruption affected RNA editing in vivo, whereas the REL2 RNA ligase gene could be down-regulated with no effect on cell growth or on RNA editing. We performed down-regulation of REL1 in procyclic T. brucei (midgut insect forms) by RNA interference and found a 40-50% inhibition of Cyb editing, which has only U-insertions, as well as a similar inhibition of ND7 editing, which has both U-insertions and U-deletions. In addition, both U-insertion and U-deletion in vitro pre-cleaved editing were inhibited to similar extents. We also found little if any effect of REL1 down-regulation on the sedimentation coefficient or abundance of the RNA ligase-containing L-complex (Aphasizhev, R., Aphasizheva, I., Nelson, R. E., Gao, G., Simpson, A. M., Kang, X., Falick, A. M., Sbicego, S., and Simpson, L. (2003) EMBO J. 22, 913-924), suggesting that the inhibition of both insertion and deletion editing was not due to a disruption of the L-complex. Together with the evidence that down-regulation of REL2 has no effect on cell growth or on RNA editing in vivo or in vitro, these data suggest that the REL1 RNA ligase may be active in vivo in both U-insertion and U-deletion editing. The in vivo biological role of REL2 remains obscure.
Howard Hughes Medical Institute, University of California, 6780 MacDonald Research Laboratories, Los Angeles, California 90095, USA.
Guanghan
G
Gao
Larry
L
Simpson
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D019729:Carbon-Oxygen Ligases / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D005990:Glycerol / Q000494:pharmacology; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000502:physiology*; D010766:Phosphorylation; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D017393:RNA Editing; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology; D013997:Time Factors; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D012313:RNA; D019729:Carbon-Oxygen Ligases; C476580:REL1 RNA ligase, Trypanosoma brucei; C476581:REL2 RNA ligase, Trypanosoma brucei; D013752:Tetracycline; D005990:Glycerol