Authors

RB Roscoe¹; F Olmo¹; JM Kelly¹; FC Costa¹; MC Taylor¹;  ¹ London School of Hygiene and tropical Medicine (LSHTM), UK

Discussion

Pantothenate kinase (PANK), a ubiquitous enzyme required for coenzyme A biosynthesis, is an antimicrobial drug target with proven essentiality to growth of bacteria, fungi and Apicomplexa. Kinetoplastids, including pathogens Trypanosoma cruzi, T. brucei and Leishmania, possess a unique PANK wherein the PANK gene has undergone fusion to two other enzyme domains. Homology suggests the presence of phosphodiesterase and adenylating activity within these multi-functional proteins and in vitro analyses demonstrate their essentiality to parasite growth and survival. Essentiality to T. cruzi epimastigotes was suggested by failure to generate homozygous null mutants using CRISPR-cas9 mediated editing. RNAi experiments revealed that PANK is essential to bloodstream-form T. brucei and is functionally homologous in the two organisms, allowing T. brucei to be used as a model for analysis of the T. cruzi PANK (TcPANK). Using this model, we showed that the amino acid residue R1270 in TcPANK is critical for enzyme activity and that the unique fused domains are required for growth. In addition, TcPANK undergoes potent negative feedback inhibition by coenzyme A and acetyl coenzyme A. These are the first characterisations of the unique kinetoplastid PANKs and evidence for therapeutic exploitability of the coenzyme A synthesis pathway in these organisms.