Activation of Anopheles stephensi Pantothenate Kinase and Coenzyme A Biosynthesis Reduces Infection with Diverse Plasmodium Species in the Mosquito Host.

Raquel M Simão-Gurge,Shirley Luckhart,Jun Isoe,Lillian R Delacruz,Jessica Strickland,Brandi K Torrevillas,Michael A Riehle,Anna M Rodriguez,Neha Thakre

doi:10.3390/biom11060807

Abstract

Malaria parasites require pantothenate from both human and mosquito hosts to synthesize coenzyme A (CoA). Specifically, mosquito-stage parasites cannot synthesize pantothenate de novo or take up preformed CoA from the mosquito host, making it essential for the parasite to obtain pantothenate from mosquito stores. This makes pantothenate utilization an attractive target for controlling sexual stage malaria parasites in the mosquito. CoA is synthesized from pantothenate in a multi-step pathway initiated by the enzyme pantothenate kinase (PanK). In this work, we manipulated A. stephensi PanK activity and assessed the impact of mosquito PanK activity on the development of two malaria parasite species with distinct genetics and life cycles: the human parasite Plasmodium falciparum and the mouse parasite Plasmodium yoelii yoelii 17XNL. We identified two putative A. stephensi PanK isoforms encoded by a single gene and expressed in the mosquito midgut. Using both RNAi and small molecules with reported activity against human PanK, we confirmed that A. stephensi PanK manipulation was associated with corresponding changes in midgut CoA levels. Based on these findings, we used two small molecule modulators of human PanK activity (PZ-2891, compound 7) at reported and ten-fold EC50 doses to examine the effects of manipulating A. stephensi PanK on malaria parasite infection success. Our data showed that oral provisioning of 1.3 nM and 13 nM PZ-2891 increased midgut CoA levels and significantly decreased infection success for both Plasmodium species. In contrast, oral provisioning of 62 nM and 620 nM compound 7 decreased CoA levels and significantly increased infection success for both Plasmodium species. This work establishes the A. stephensi CoA biosynthesis pathway as a potential target for broadly blocking malaria parasite development in anopheline hosts. We envision this strategy, with small molecule PanK modulators delivered to mosquitoes via attractive bait stations, working in concert with deployment of parasite-directed novel pantothenamide drugs to block parasite infection in the human host. In mosquitoes, depletion of pantothenate through manipulation to increase CoA biosynthesis is expected to negatively impact Plasmodium survival by starving the parasite of this essential nutrient. This has the potential to kill both wild type parasites and pantothenamide-resistant parasites that could develop under pantothenamide drug pressure if these compounds are used as future therapeutics for human malaria.

Highlights

Malaria remains a devastating disease and significant efforts have focused on developing novel therapeutics, vaccines, and mosquito-targeted strategies to eliminate human infection and disrupt parasite transmission
We demonstrated that P. falciparum infection of A. stephensi increased activation of c-Jun N-terminal kinase (JNK) signaling in the mosquito midgut and, that inhibition of JNK signaling activation was associated with increased coenzyme A (CoA) biosynthesis and expression of A. stephensi pantothenate kinase (PanK) in the mosquito midgut [12]
We proposed that parasiteinduced JNK signaling would benefit the parasite by decreasing competition with the mosquito host for pantothenate, with studies showing that JNK signaling inhibition was associated with upregulated CoA synthesis in the A. stephensi midgut and increased resistance to P. falciparum infection [12]

Summary

Introduction

Malaria remains a devastating disease and significant efforts have focused on developing novel therapeutics, vaccines, and mosquito-targeted strategies to eliminate human infection and disrupt parasite transmission. Malaria parasites must acquire essential host resources that they are unable to synthesize for themselves. Plasmodium spp. cannot synthesize pantothenate de novo and, must acquire pantothenate from the vertebrate and mosquito hosts for survival [1,2]. Malaria parasites, like both of their hosts, convert pantothenate to coenzyme A (CoA), a critical co-factor for metabolism, via the initial enzyme in the CoA biosynthesis pathway, pantothenate kinase (PanK)

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