title: A novel high-throughput activity assay for the Trypanosoma brucei editosome enzyme REL1 and other RNA ligases.
abstract: The protist parasite Trypanosoma brucei causes Human African trypanosomiasis (HAT), which threatens millions of people in sub-Saharan Africa. Without treatment the infection is almost always lethal. Current drugs for HAT are difficult to administer and have severe side effects. Together with increasing drug resistance this results in urgent need for new treatments. T. brucei and other trypanosomatid pathogens require a distinct form of post-transcriptional mRNA modification for mitochondrial gene expression. A multi-protein complex called the editosome cleaves mitochondrial mRNA, inserts or deletes uridine nucleotides at specific positions and re-ligates the mRNA. RNA editing ligase 1 (REL1) is essential for the re-ligation step and has no close homolog in the mammalian host, making it a promising target for drug discovery. However, traditional assays for RELs use radioactive substrates coupled with gel analysis and are not suitable for high-throughput screening of compound libraries. Here we describe a fluorescence-based REL activity assay. This assay is compatible with a 384-well microplate format and sensitive, satisfies statistical criteria for high-throughput methods and is readily adaptable for other polynucleotide ligases. We validated the assay by determining kinetic properties of REL1 and by identifying REL1 inhibitors in a library of small, pharmacologically active compounds.
authors.affiliation: Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK.
authors.forename: Stephan
authors.initials: S
authors.lastname: Zimmermann
authors.affiliation: Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK.
authors.forename: Laurence
authors.initials: L
authors.lastname: Hall
authors.affiliation: The Scripps Research Institute, 4122 Sorrento Valley Boulevard, San Diego, CA 92121, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Riley
authors.affiliation: Department of Chemistry & Biochemistry and the National Biomedical Computation Resource, University of California, San Diego, CA 92093, USA.
authors.forename: Jesper
authors.initials: J
authors.lastname: Sørensen
authors.affiliation: Department of Chemistry & Biochemistry and the National Biomedical Computation Resource, University of California, San Diego, CA 92093, USA.
authors.forename: Rommie E
authors.initials: RE
authors.lastname: Amaro
authors.affiliation: Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK achim.schnaufer@ed.ac.uk.
authors.forename: Achim
authors.initials: A
authors.lastname: Schnaufer
mesh_terms: D000818:Animals; D019729:Carbon-Oxygen Ligases / Q000235:genetics* / Q000378:metabolism; D020134:Catalytic Domain; D057166:High-Throughput Screening Assays / Q000379:methods*; D007700:Kinetics; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D013498:Suramin / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
chemical_list: D024101:Mitochondrial Proteins; D013498:Suramin; D019729:Carbon-Oxygen Ligases; C476580:REL1 RNA ligase, Trypanosoma brucei