Structural studies of trypanosomal tRNA synthetases as drug targets for African Animal Trypanosomiasis

  • James J Day

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

African Animal Trypanosomiasis is a disease that primarily afflicts cattle in Africa. It affects at least 37 countries in the region and, in 2017, was estimated to be responsible for the overall loss of around £4.75 billion per annum to the rural economy. The various symptoms, ultimately leading to the deaths of over 3 million cattle per year, result in a reduction of every aspect of livestock farming and it is therefore considered a severe repressor of central African development both cultural and economic.

It is caused by the group of parasitic protozoa called Trypanosoma, which are carried by all flies of the ‘Glossina’ genus (tsetse flies) and renders large swathes of rural Africa – particularly the ‘tsetse belt’ – unsuitable for cattle farming. The two organisms most significant in causing this widespread economic repression are Trypanosoma congolense and Trypanosome vivax. Aminoacyl tRNA synthetase enzymes have been previously identified as promising potential drug targets in T. congolense and, in this study, that potential is being explored through the generation of crystal structures of those enzymes.

Three structures of T. congolense lysyl-tRNA Synthetase I (LysRS1) have been solved following expression in Rosetta 2 pLacI E. coli cells and purification using cobalt affinity chromatography and size exclusion chromatography. The structures contain LysRS1 complexed with lysine and AMP (LAM_G4; 1.9 Å), with the lysyl-AMP intermediate (LAM_H2; 2.2 Å) and with the nucleoside analogue cordycepin (LCM_F3; 2.4 Å). These structures provide a detailed description of the T. congolense LysRS1 active site and comparing these structures with mammalian LysRS enables identification of differences in the ATP-binding site that could be exploited in structure-based drug-design. Furthermore, conformational changes in a pair of loops associated with the active site may be significant for enzyme activity and specificity.
Date of Award7 May 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorR L Brady (Supervisor) & J L R Anderson (Supervisor)

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