Composition of the editing complex of Trypanosoma brucei.
The RNA editing that produces most functional mRNAs in trypanosomes is catalysed by a multiprotein complex. This complex catalyses the endoribonucleolytic cleavage, uridylate addition and removal, and RNA ligation steps of the editing process. Enzymatic and in vitro editing analyses reveal that each catalytic step contributes to the specificity of the editing and, together with the interaction between gRNA and the mRNA, results in precisely edited mRNAs. Tandem mass spectrometric analysis was used to identify the genes for several components of biochemically purified editing complexes. Their identity and presence in the editing complex were confirmed using immunochemical analyses utilizing mAbs specific to the editing complex components. The genes for two RNA ligases were identified. Genetic studies show that some, but not all, of the components of the complex are essential for editing. The TbMP52 RNA ligase is essential for editing while the TbMP48 RNA ligase is not. Editing was found to be essential in bloodstream form trypanosomes. This is surprising because mutants devoid of genes encoding RNAs that become edited survive as bloodstream forms but encouraging since editing complex components may be targets for chemotherapy.
Stuart
K
K
Seattle Biomedical Research Institute, 4 Nickerson Street, Seattle, WA 98109, USA. kstuart@u.washington.edu
Panigrahi
A K
AK
Schnaufer
A
A
Drozdz
M
M
Clayton
C
C
Salavati
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004720:Endonucleases / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D046911:Macromolecular Substances; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D019761:Phosphorus-Oxygen Lyases / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D017393:RNA Editing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014346:Trypanosoma brucei brucei / Q000201:enzymology / Q000235:genetics*
D046911:Macromolecular Substances; D046912:Multiprotein Complexes; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; C418993:TbMP52 protein, Trypanosoma brucei; D004720:Endonucleases; D019761:Phosphorus-Oxygen Lyases; D008025:Ligases; C418994:MP48 protein, Trypanosoma brucei