Differential mitochondrial gene expression between slender and stumpy bloodforms of Trypanosoma brucei

Feagin, Jean E.; Jasmer, Douglas P.; Stuart, Kenneth

doi:10.1016/0166-6851(86)90100-3

Cited by 57 publications

(14 citation statements)

References 28 publications

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“…The two life forms of T. brucei grow at different temperatures: the insect stage grows at 27°C, and the bloodstream stage grows at 37°C. In addition, while mRNA transcripts are found in both life stages, their abundance does appear to be differentially controlled (8,9,11,15,20), and we have shown that the relative gRNA-tomRNA ratios can differ between the different life forms. It may be that differences in the specific affinities between the gRNAs and the editing complex at the different life stage temperatures, combined with differences in the ratios of gRNA to mRNA transcripts, may combine to provide a finely tuned mechanism for the regulation of editing in specific transcripts.…”

Section: Methodsmentioning

confidence: 99%

Guide RNAs for transcripts with developmentally regulated RNA editing are present in both life cycle stages of Trypanosoma brucei.

Koslowsky¹,

Riley²,

Feagin³

et al. 1992

Mol. Cell. Biol.

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RNA editing of several mitochondrial transcripts in Trypanosoma brucei is developmentally regulated. The cytochrome b and cytochrome oxidase II mRNAs are edited in procyclic-form parasites but are primarily unedited in bloodstream forms. The latter forms lack the mitochondrial respiratory system present in procyclic forms. Editing of the NADH dehydrogenase 7 (ND7) and ND8 transcripts is also developmentally regulated but occurs preferentially in bloodstream forms. Other transcripts, cytochrome oxidase III and ATPase 6, are edited in both life forms. We have identified many minicircle-encoded guide RNAs (gRNAs) for ATPase 6, ND7, and ND8. The characteristics of these gRNAs reveal how extensively edited RNA can be edited in the 3'-to-5' direction. Northern (RNA) blot and primer extension analyses indicate that gRNAs for transcripts whose editing is developmentally regulated are present in both procyclic and bloodstream form parasites. These results suggest that the developmental regulation of editing in these transcripts is not controlled by the presence or absence of gRNAs.

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Section: Methodsmentioning

confidence: 99%

Guide RNAs for transcripts with developmentally regulated RNA editing are present in both life cycle stages of Trypanosoma brucei.

Koslowsky¹,

Riley²,

Feagin³

et al. 1992

Mol. Cell. Biol.

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“…Clone IsTaR 1 of T. brucei brucei (stock EATRO 164) was grown in rats and in procyclic culture and harvested as previously described (20). Stumpy bloodstream forms of this stock were produced by treatment with 2% DFMO, as previously described (8). Populations which were exposed to small amounts of DFMO retained the morphological appearance of slender forms, whereas those treated with larger amounts differentiated to -40o stumpy forms.…”

Section: Methodsmentioning

confidence: 99%

“…All of the putative protein-coding genes except ND5 have two size classes of transcripts which differ by an apparent 150 to 200 nucleotides (nt) (7,10,13,21). The larger size class of CYb, COI, and COII transcripts is more abundant in stumpy forms than slender forms and is most abundant in procyclic forms, whereas the smaller size class of transcript for many genes is most abundant in stumpy forms (7,8,10,13,21). In stocks of T. brucei which do not spontaneously * Corresponding author.…”

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“…In stocks of T. brucei which do not spontaneously * Corresponding author. differentiate to stumpy forms, difluoromethylornithine (DFMO) treatment of slender forms results in a stumpy morphology (1,4,8,11) and a transcript abundance pattern which is very similar to that of spontaneously occurring stumpy forms (8). Polyadenylation is also differentially regulated between life cycle stages, with a larger proportion of mitochondrial transcripts being polyadenylated in procyclic forms than in slender ones (21).…”

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Developmental aspects of uridine addition within mitochondrial transcripts of Trypanosoma brucei.

1988

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The mitochondrial respiratory system is absent in slender bloodstream forms of Trypanosoma brucei, incomplete in stumpy bloodstream forms, and complete in procyclic (insect) forms. The steady-state abundance of transcripts of some mitochondrially encoded components of the respiratory system correlates with its differential expression in different life cycle stages. Recently, it was reported that uridines which are not encoded in the genome are added to cytochrome b and cytochrome oxidase II transcripts. We now report that the (U)+ transcripts of both genes are found in procyclic forms and to some degree in stumpy forms but are absent in slender forms. The uridine additions to cytochrome oxidase II correct a frameshift in the gene and presumably allow production of a full-length protein, whereas those added to cytochrome b create an in-frame AUG which extends the N terminus of the predicted protein by 20 amino acids. The stage specificity of uridine additions to these transcripts thus reflects the life cycle stage during which the protein products would be used. Transcripts of MURF2, a gene of unknown function, have additional uridines in both slender and procyclic forms which create two in-frame AUGs. MURF2 transcripts additionally differ from the DNA sequence in ways which cannot be explained by uridine addition alone, implying that other processes alter these transcripts.

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“…Editing of the mitochondrial mRNAs is regulated dur-ing the life cycle of trypanosomes and the pattern of which mRNAs are edited parallels the differences in energy metabolism between the life-cycle stages (Feagin et al 1986). The mRNAs for cytochromes are edited in PFs of Trypanosoma brucei in which energy is generated by cytochrome-mediated oxidative phosphorylation but are not edited in slender BFs where energy is generated by glycolysis.…”

Section: Introductionmentioning

confidence: 99%

Composition of the editing complex ofTrypanosoma brucei

Stuart

Panigrahi

Schnaufer

et al. 2002

Phil. Trans. R. Soc. Lond. B

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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 speci city 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 puri ed editing complexes. Their identity and presence in the editing complex were con rmed using immunochemical analyses utilizing mAbs speci c to the editing complex components. The genes for two RNA ligases were identi ed. 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.

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Differential mitochondrial gene expression between slender and stumpy bloodforms of Trypanosoma brucei

Cited by 57 publications

References 28 publications

Guide RNAs for transcripts with developmentally regulated RNA editing are present in both life cycle stages of Trypanosoma brucei.

Guide RNAs for transcripts with developmentally regulated RNA editing are present in both life cycle stages of Trypanosoma brucei.

Developmental aspects of uridine addition within mitochondrial transcripts of Trypanosoma brucei.

Composition of the editing complex ofTrypanosoma brucei

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