Phosphoethanolamine methyltransferases inhibitors with broad-spectrum anthelmintic effect against livestock nematodes

Zhang, Xuejin

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https://hdl.handle.net/2142/115908 Copy

Description

Title

Phosphoethanolamine methyltransferases inhibitors with broad-spectrum anthelmintic effect against livestock nematodes

Author(s)

Zhang, Xuejin

Issue Date

2022-07-11

Director of Research (if dissertation) or Advisor (if thesis)

Witola, William Harold

Doctoral Committee Chair(s)

Witola, William Harold

Committee Member(s)

• Lau, Gee
• Nanjappa, Som G.
• Das, Aditi

Department of Study

Pathobiology

Discipline

VMS - Pathobiology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• nematode
• methyltransferase
• anthelmintic

Abstract

In the United States and world-over, nematode infections are among the most economically important factors affecting livestock health and production, costing the global livestock industry billions of dollars annually. Anthelmintic drugs are the primary means of controlling live-stock nematodes, but there is now a high prevalence of anthelmintic-resistant nematodes. Thus, there is urgent need to identify novel strategies for developing new efficacious anthelmintic drugs. The long-term goal of this study is to identify and validate molecular targets for developing new effective drugs with novel modes of action to kill nematodes and circumvent anthelmintic resistance. Specifically, this project aimed to identify inhibitors for essential phospholipid bio-synthetic enzymes in nematodes as lead compounds for developing novel, broad-spectrum anthelmintic drugs. We had earlier found that two phosphoethanolamine methyltransferases (PMTs) that catalyze the biosynthesis of phosphatidylcholine are essential for the survival of the livestock nematode Haemonchus contortus, and that specific inhibitors for these PMTs can kill the parasite. In the present study, we identified orthologous genes for PMTs in other livestock nematodes within the families Ancylostomatoidea, Ascarididae, Chabertiidae, Dictyocaulidae, and Tricho-strongylidae. We cloned, expressed, column affinity-purified, and performed enzymatic characterization of those putative PMT proteins and found that they possess bona fide PMT catalytic activities. By complementing a mutant yeast strain lacking the ability to endogenously synthesize phosphatidylcholine (that is essential for yeast growth in medium without choline), we validated that nematode PMTs are critical bona fide enzymes in the biosynthesis of phosphatidylcholine. Subsequently, using an in vitro fluorescence-based methyltransferase assay, in which PMTs function as catalytic enzymes, we screened a natural compound library and identified compounds with cross-inhibitory effects against the various nematode PMTs. Corroboratively, treatment of PMT-complemented yeast with the inhibitors blocked the growth of the yeast in medium lacking choline, underscoring the essential role of nematode PMTs in phosphatidylcholine synthesis, and as molecular targets for anthelmintic drug development. In conclusion, this study has validated druggable molecular targets conserved in a broad range of nematodes and identified lead-compounds for developing novel and effective broad-spectrum anthelmintic drugs for treating livestock nematode infections. This will ultimately improve livestock health and enhance food security.

Graduation Semester

2022-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Xuejin Zhan

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