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  • Title: The PARP promoter of Trypanosoma brucei is developmentally regulated in a chromosomal context.
    Author: Biebinger S, Rettenmaier S, Flaspohler J, Hartmann C, Peña-Diaz J, Wirtz LE, Hotz HR, Barry JD, Clayton C.
    Journal: Nucleic Acids Res; 1996 Apr 01; 24(7):1202-11. PubMed ID: 8614620.
    Abstract:
    African trypanosomes are extracellular protozoan parasites that are transmitted from one mammalian host to the next by tsetse flies. Bloodstream forms express variant surface glycoprotein (VSG); the tsetse fly (procyclic) forms express instead the procyclic acidic repetitive protein (PARP). PARP mRNA is abundant in procyclic forms and almost undetectable in blood-stream forms. Post-transcriptional mechanisms are mainly responsible for PARP mRNA regulation but results of nuclear run-on experiments suggested that transcription might also be regulated. We measured the activity of genomically-integrated PARP, VSG and rRNA promoters in permanently-transformed blood-stream and procyclic form trypanosomes, using reporter gene constructs that showed no post-transcriptional regulation. When the constructs were integrated in the rRNA non-transcribed spacer, the ribosomal RNA and VSG promoters were not developmentally regulated, but integration at the PARP locus reduced rRNA promoter activity in bloodstream forms. PARP promoter activity was 5-fold down-regulated in bloodstream forms when integrated at either site. Regulation was probably at the level of transcriptional initiation, but elongation through plasmid vector sequences was also reduced.
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