Factors that bind to RNA polymerase I promoter sequences of Trypanosoma brucei

Janz, L; Hug, Michael; Clayton, Christine

doi:10.1016/0166-6851(94)90119-8

Cited by 17 publications

(8 citation statements)

References 27 publications

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“…These results confirm that, for the hybrid rRNA-PARP promoters, the initiation sites were similar or identical to those used by the species providing the start site. Preliminary results indicate that the same is true for hybrid PARP-rRNA promoters (18). These results are therefore consistent with transcription of PARP, rRNA, and hybrid promoters by the same polymerase.…”

Section: Resultssupporting

confidence: 77%

“…From this evidence, one might expect the PARP and rRNA promoters to compete for transcription factors. We have been unable to confirm this by gel mobility shift analysis (19), and it is unlikely to be possible to test by transient transfection because the system is not easily saturated (48 (14,39). RNA polymerase II transcription also appears inefficient in comparison with transcription by RNA polymerase I: a single neomycin phosphotransferase gene integrated at the rRNA locus gave 5-to 10-fold more RNA than an analogous construct integrated in the tubulin array (35), and integrated luciferase genes show a similar difference in expression (41b).…”

Section: Discussionmentioning

confidence: 97%

See 1 more Smart Citation

The PARP and rRNA promoters of Trypanosoma brucei are composed of dissimilar sequence elements that are functionally interchangeable.

Janz¹,

Clayton²

1994

Mol. Cell. Biol.

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The African trypanosomes express two major surface proteins, the variant surface glycoprotein (VSG) and the procyclic acidic repetitive protein (PARP). The RNA polymerase that transcribes the VSG and PARP genes shares many characteristics with RNA polymerase l. We show that although there is very little similarity in nucleotide sequence, the functional structure of a trypanosome rRNA promoter is almost identical to that of the PARP promoter. Further, domains from the PARP promoter can functionally substitute for the corresponding parts of the rRNA promoter, and vice versa.

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Section: Resultssupporting

confidence: 77%

Section: Discussionmentioning

confidence: 97%

The PARP and rRNA promoters of Trypanosoma brucei are composed of dissimilar sequence elements that are functionally interchangeable.

Janz¹,

Clayton²

1994

Mol. Cell. Biol.

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“…In this respect, our results contradict those of Janz et al (17) with the procyclin promoter, perhaps because of the use of different experimental conditions. In striking contrast, a specific binding was clearly observed when nuclear extracts were incubated with a singlestranded probe, namely, the noncoding strand of box 2.…”

Section: Discussioncontrasting

confidence: 57%

“…We present here such an analysis. This should be compared with similar analyses of the procyclin promoter, already presented by different groups (5,6,16,17,28).…”

Section: Discussionmentioning

confidence: 99%

Specific Binding of Proteins to the Noncoding Strand of a Crucial Element of the Variant Surface Glycoprotein, Procyclin, and Ribosomal Promoters of Trypanosoma brucei

Vanhamme¹,

Pays²,

Tebabi³

et al. 1995

Molecular and Cellular Biology

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The variant surface glycoprotein (VSG) and procyclin promoters of Trypanosoma brucei recruit an RNA polymerase sharing characteristics with polymerase I, but there is no sequence homology between them nor between these promoters and ribosomal promoters. We report the detailed characterization of the VSG promoter. The 70-bp region upstream of the transcription start site was sufficient for full promoter activity. Mutational analysis revealed three short critical stretches at positions ؊61 to ؊59 (box 1), ؊38 to ؊35 (box 2), and ؊1 to ؉1 (start site), the spacing of which was essential. These elements were conserved in the promoter for a metacyclic VSG gene. Hybrid sequences containing box 1 of the VSG promoter and box 2 of the ribosomal promoter were active. A specific binding of proteins to the noncoding strand of box 2, but not to double-stranded DNA, occurred. Competition experiments indicated that these proteins also bind to the corresponding region of the metacyclic VSG, procyclin, and ribosomal promoters. Binding of such a protein, of 40 kDa, appeared to be shared by these promoters.The protozoan parasite Trypanosoma brucei shares its life cycle between mammals and an insect vector, the tsetse fly. The bloodstream (mammalian) form and the procyclic (insect) form are uniformly covered by a surface coat, of variant surface glycoprotein (VSG) and procyclin, respectively. The VSG replaces procyclin when procyclic forms differentiate into metacyclic forms in the salivary glands of the fly. This surface antigen persists throughout the development of the parasite in the blood and rapidly disappears when procyclin is reexpressed upon differentiation from the bloodstream to the procyclic form. Therefore, the VSG and procyclin are typical markers for the major developmental stages of the parasite (for recent reviews, see references 4, 10, 24, and 25).African trypanosomes are responsible for important human and animal plagues. They escape the immune defenses of their hosts by a periodical change of their antigenic VSG coat. The study of the control of VSG expression is thus of major fundamental and economic importance. However, the mechanisms controlling gene expression in trypanosomatids are poorly understood. This is particularly true for transcriptional controls. Because of the general organization of genes into polycistronic transcription units, there is only limited information on transcription promoters and their controls. The only promoters for protein-coding genes that are known so far are those of VSG and procyclin (11,12, 23,26,31,32). There are two diploid loci for the procyclin transcription units, and it is believed that the promoters of all these units are simultaneously active in the procyclic form (11,20). The number of VSG transcription units is estimated to be between 6 and 20 (4, 24), but only a single one is expressed at a given time. So far it is not clear if this control operates at the level of promoter activity or transcription attenuation. Interestingly, although the VSG and procyclin units ar...

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“…Moreover, despite a lack of homology, one of these stretches appears to bind common factors (192). Interestingly, the binding of specific proteins requires that the target DNA be single-stranded (29,192), and the binding of proteins common to the three promoters is not observed on doublestranded DNA (87,192). These results suggest that these promoters should be partially denatured to be functional (29,192).…”

Section: Unusual Transcription Promotersmentioning

confidence: 99%