Diverse patterns of expression of the cytochrome c oxidase subunit I gene and unassigned reading frames 4 and 5 during the life cycle of Trypanosoma brucei.

Transcription of a maxicircle segment from Trypanosoma brucei 164 that contains nucleotide (nt) sequences corresponding to cytochrome c oxidase subunit I (COI) and unassigned reading frames (URFs) 4 and 5 of other mitochondrial systems was investigated. Two major transcripts that differ in size by ca. 200 nt map to each of the COI and URF4 genes, while a single major transcript maps to URF5. In total RNA, the larger COI transcript is more abundant in procyclic forms (PFs) than in bloodstream forms (BFs), the smaller COI and both URF4 transcripts have similar abundances in both forms, and the single URF5 transcript is more abundant in BF than PF. These patterns of expression differ in poly(A)+ RNA as a result of a higher proportion of poly(A)+ mitochondrial transcripts in PFs than in BFs. In addition, small (300- to 500-nt) RNAs that are transcribed from C-rich sequences located between putative protein-coding genes also exhibit diverse patterns of expression between life cycle stages and differences in polyadenylation in PFs compared with BFs. These observations suggest that multiple processes regulate the differential expression of mitochondrial genes in T. brucei.

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Developmental aspects of uridine addition within mitochondrial transcripts of Trypanosoma brucei

Molecular and Cellular Biology ◽

10.1128/mcb.8.3.1259-1265.1988 ◽

1988 ◽

Vol 8 (3) ◽

pp. 1259-1265

Author(s):

J E Feagin ◽

K Stuart

Keyword(s):

Life Cycle ◽

Cytochrome Oxidase ◽

Trypanosoma Brucei ◽

Cytochrome B ◽

Respiratory System ◽

Life Cycle Stage ◽

Stage Specificity ◽

Life Cycle Stages ◽

Mitochondrial Transcripts ◽

Cytochrome Oxidase Ii

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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Identification of mitochondrial genes in Trypanosoma brucei and homology to cytochrome c oxidase II in two different reading frames

Molecular and Biochemical Parasitology ◽

10.1016/0166-6851(85)90117-3 ◽

1985 ◽

Vol 15 (2) ◽

pp. 159-170 ◽

Cited By ~ 27

Author(s):

Mark Payne ◽

Victoria Rothwell ◽

Douglas P. Jasmer ◽

Jean E. Feagin ◽

Kenneth Stuart

Keyword(s):

Cytochrome C ◽

Cytochrome C Oxidase ◽

Trypanosoma Brucei ◽

Mitochondrial Genes ◽

Reading Frames

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

Molecular and Cellular Biology ◽

10.1128/mcb.8.3.1259 ◽

1988 ◽

Vol 8 (3) ◽

pp. 1259-1265 ◽

Cited By ~ 81

Author(s):

J E Feagin ◽

K Stuart

Keyword(s):

Life Cycle ◽

Cytochrome Oxidase ◽

Trypanosoma Brucei ◽

Cytochrome B ◽

Respiratory System ◽

Life Cycle Stage ◽

Stage Specificity ◽

Life Cycle Stages ◽

Mitochondrial Transcripts ◽

Cytochrome Oxidase Ii

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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