Protein stability regulates the expression of cytochrome c during the developmental cycle of Trypanosoma brucei.
The expression of cytochrome c is developmentally regulated during the life cycle of Trypanosoma brucei. The level of regulation appears to be post-transcriptional since cytochrome c mRNA is present in all life stages of the parasite. We have used RNA from each life stage to prime in vitro translation systems and found that the cytochrome c mRNAs are equally translatable. Continuous labeling experiments conducted in vivo indicate that cytochrome c is synthesized at similar rates in both bloodstream and procyclic trypanosomes. Western blots, however, confirm that steady-state levels of cytochrome c are severely depressed in bloodstream forms. In a series of pulse/chase experiments we demonstrate that the half-life of cytochrome c is approximately 1 h in the bloodstream form and no detectable turnover occurred in the procyclic form. We conclude that a major step in the developmental regulation of cytochrome c expression in T. brucei occurs post-translationally due to rapid turnover of the protein in the bloodstream trypanosomes.
Department of Biochemistry, School of Medicine, University of Alabama, Birmingham 35294.
A F
AF
Torri
K I
KI
Bertrand
S L
SL
Hajduk
D000818:Animals; D001483:Base Sequence; D003574:Cytochrome c Group / Q000235:genetics / Q000378:metabolism*; D016054:DNA, Protozoan / Q000235:genetics; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D003574:Cytochrome c Group; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan