Ribosomal RNA transcription in Trypanosoma brucei – decoding RNA polymerase-I regulation in an early diverging eukaryote

Dr Sam Alsford (primary)
Infection Biology
London School of Hygiene and Tropical Medicine
Prof John Kelly (secondary)
Infection Biology
London School of Hygiene and Tropical Medicine


Uniquely amongst eukaryotes, Trypanosoma brucei RNA polymerase-I (RNAPI) transcribes a subset of mRNAs, including that for variant surface glycoprotein (VSG), the key mediator of antigenic variation. Research on T. brucei RNAPI transcriptional regulation has focused on its role in monoallelic VSG transcription, and relatively little is known about rDNA array transcriptional regulation. The T. brucei haploid genome contains nine rDNA arrays, only a subset of which are transcriptionally active. Using reporter cell lines, RNAi library selection and follow-up molecular analyses we will characterise the regulatory network of cis-acting elements and trans-acting factors that ensures optimal rRNA (and VSG mRNA) transcription.


[1] Alsford S, Kawahara T, Glover L, Horn D. (2005) Tagging a Trypanosoma brucei RRNA locus improves stable transfection efficiency and circumvents inducible expression position effects. Mol Biochem Parasitol. 144:142-8.
[2] Alsford S and Horn D. (2011) Elongator protein 3b negatively regulates ribosomal DNA transcription in African trypanosomes. Mol Cell Biol. 31:1822-32.
[3] McLatchie AP, Burrell-Saward H, Myburgh E, Lewis MD, Ward TH, Mottram JC, Croft SL, Kelly JM, Taylor MC. (2014) Highly sensitive in vivo imaging of Trypanosoma brucei expressing “red-shifted” luciferase. PLoS Negl Trop Dis. 7:e2571.
[4] Lewis MD, Fortes Francisco A, Taylor MC, Burrell-Saward H, McLatchie AP, Miles MA, Kelly JM. (2014) Bioluminescence imaging of chronic Trypanosoma cruzi infections reveals tissue-specific parasite dynamics and heart disease in the absence of locally persistent infection. Cell Microbiol. 16:1285-300.
[5] Glover L, Alsford S, Baker N, Turner DJ, Sanchez-Flores A, Hutchinson S, Hertz-Fowler C, Berriman M, Horn D. (2015) Genome-scale RNAi screens for high-throughput phenotyping in bloodstream-form African trypanosomes. Nat Protoc. 10:106-33.
[6] Currier RB, Cooper A, Burrell-Saward H, MacLeod A, Alsford S. (2018) Decoding the network of Trypanosoma brucei proteins that determines sensitivity to apolipoprotein-L1. PLoS Pathog. 14:e1006855.
[7] Alsford S and Horn D. (2008) Single-locus targeting constructs for reliable regulated RNAi and transgene expression in Trypanosoma brucei. Mol Biochem Parasitol. 161:76-9.
[8] Wickstead B, Ersfeld K, Gull K. (2002) Targeting of a tetracycline-inducible expression system to the transcriptionally silent minichromosomes of Trypanosoma brucei. Mol Biochem Parasitol. 125:211-6.

Animal disease, health and welfare
Area of Biology
Cell BiologyMicrobiology
Techniques & Approaches
BiochemistryBioinformaticsMicroscopy / ElectrophysiologyMolecular Biology