Protein Translation Enzyme lysyl-tRNA Synthetase Presents a New Target for Drug Development against Causative Agents of Loiasis and Schistosomiasis

PLoS Negl Trop Dis. 2016 Nov 2;10(11):e0005084. doi: 10.1371/journal.pntd.0005084. eCollection 2016 Nov.

Abstract

Helminth parasites are an assemblage of two major phyla of nematodes (also known as roundworms) and platyhelminths (also called flatworms). These parasites are a major human health burden, and infections caused by helminths are considered under neglected tropical diseases (NTDs). These infections are typified by limited clinical treatment options and threat of drug resistance. Aminoacyl-tRNA synthetases (aaRSs) are vital enzymes that decode genetic information and enable protein translation. The specific inhibition of pathogen aaRSs bores well for development of next generation anti-parasitics. Here, we have identified and annotated aaRSs and accessory proteins from Loa loa (nematode) and Schistosoma mansoni (flatworm) to provide a glimpse of these protein translation enzymes within these parasites. Using purified parasitic lysyl-tRNA synthetases (KRSs), we developed series of assays that address KRS enzymatic activity, oligomeric states, crystal structure and inhibition profiles. We show that L. loa and S. mansoni KRSs are potently inhibited by the fungal metabolite cladosporin. Our co-crystal structure of Loa loa KRS-cladosporin complex reveals key interacting residues and provides a platform for structure-based drug development. This work hence provides a new direction for both novel target discovery and inhibitor development against eukaryotic pathogens that include L. loa and S. mansoni.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Anthelmintics / chemistry*
  • Anthelmintics / pharmacology
  • Drug Discovery
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / pharmacology
  • Helminth Proteins / antagonists & inhibitors*
  • Helminth Proteins / chemistry
  • Helminth Proteins / genetics
  • Helminth Proteins / metabolism
  • Humans
  • Kinetics
  • Loa / drug effects
  • Loa / enzymology*
  • Loa / genetics
  • Loiasis / drug therapy
  • Loiasis / parasitology*
  • Lysine-tRNA Ligase / antagonists & inhibitors*
  • Lysine-tRNA Ligase / chemistry
  • Lysine-tRNA Ligase / genetics
  • Lysine-tRNA Ligase / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Schistosoma mansoni / drug effects
  • Schistosoma mansoni / enzymology*
  • Schistosoma mansoni / genetics
  • Schistosomiasis / drug therapy
  • Schistosomiasis / parasitology*
  • Sequence Alignment

Substances

  • Anthelmintics
  • Enzyme Inhibitors
  • Helminth Proteins
  • Lysine-tRNA Ligase

Grants and funding

This work is supported by COE grant from DBT for work on parasitic protein translation enzymes to AmS who is a JC Bose fellow. ArS is supported by the Council of Scientific & Industrial Research (CSIR) Senior Research Fellowship (SRF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.