Plasmodium falciparum Calcium-Dependent Protein Kinase 2 Is Critical for Male Gametocyte Exflagellation but Not Essential for Asexual Proliferation.

Abhisheka Bansal,Jianbing Mu,Louis H Miller,Alvaro Molina-Cruz,Joseph Brzostowski,L David Sibley

doi:10.1128/mbio.01656-17

Abhisheka Bansal, Jianbing Mu + Show 4 more

Open Access

https://doi.org/10.1128/mbio.01656-17

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Abstract

ABSTRACTDrug development efforts have focused mostly on the asexual blood stages of the malaria parasite Plasmodium falciparum. Except for primaquine, which has its own limitations, there are no available drugs that target the transmission of the parasite to mosquitoes. Therefore, there is a need to validate new parasite proteins that can be targeted for blocking transmission. P. falciparum calcium-dependent protein kinases (PfCDPKs) play critical roles at various stages of the parasite life cycle and, importantly, are absent in the human host. These features mark them as attractive drug targets. In this study, using CRISPR/Cas9 we successfully knocked out PfCDPK2 from blood-stage parasites, which was previously thought to be an indispensable protein. The growth rate of the PfCDPK2 knockout (KO) parasites was similar to that of wild-type parasites, confirming that PfCDPK2 function is not essential for the asexual proliferation of the parasite in vitro. The mature male and female gametocytes of PfCDPK2 KO parasites become round after induction. However, they fail to infect female Anopheles stephensi mosquitoes due to a defect(s) in male gametocyte exflagellation and possibly in female gametes.

Highlights

Drug development efforts have focused mostly on the asexual blood stages of the malaria parasite Plasmodium falciparum
We showed that PfCDPK2 is not required for in vitro asexual proliferation and gametocytogenesis of the malaria parasite P. falciparum
Our results indicate that PfCDPK2 plays a role in the development of the male gametes inside red blood cells (RBCs)

Summary

Introduction

Drug development efforts have focused mostly on the asexual blood stages of the malaria parasite Plasmodium falciparum. P. falciparum calcium-dependent protein kinases (PfCDPKs) play critical roles at various stages of the parasite life cycle and, importantly, are absent in the human host. These features mark them as attractive drug targets. For effective control and elimination of malaria, multiple stages of the parasite need to be targeted One such stage includes the transmission of the parasite to mosquitoes. PfCDPK1 has been shown to play a role in egress of merozoites from mature schizonts [2, 3], phosphorylation of motor complex proteins [4], and invasion of merozoites into red blood cells (RBCs) [5, 6]. A previous study predicted the putative substrates of PfCDPK2 based on results of an in vitro phosphorylation assay with a nonnatural substrate, myelin basic protein (MBP) [12]

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