Plasmodium berghei serine/threonine protein phosphatase PP5 plays a critical role in male gamete fertility |
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Authors: | Xiaotong Zhu Lin Sun Yang He Huanping Wei Mingyang Hong Fei Liu Qingyang Liu Yaming Cao Liwang Cui |
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Institution: | 1. Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning 110122, China;2. Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Boulevard, Suite 304, Tampa, FL 33612-9415, USA |
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Abstract: | Sexual development in malaria parasites involves multiple signal transduction pathways mediated by reversible protein phosphorylation. Here, we functionally characterised a protein phosphatase, Ser/Thr protein phosphatase 5 (PbPP5), during sexual development of the rodent malaria parasite Plasmodium berghei. The recombinant protein phosphatase domain displayed obvious protein phosphatase activity and was sensitive to PP1/PP2A inhibitors including cantharidic acid (IC50 = 122.2 nM), cantharidin (IC50 = 74.3 nM), endothall (IC50 = 365.5 nM) and okadaic acid (IC50 = 1.3 nM). PbPP5 was expressed in both blood stages and ookinetes with more prominent expression during sexual development. PbPP5 was localised in the cytoplasm of the parasite and highly concentrated beneath the parasite plasma membrane in free merozoites and ookinetes. Targeted deletion of the pbpp5 gene had no influence on asexual blood-stage parasite multiplication or the survival curve of the infected hosts. However, male gamete formation and fertility were severely affected, resulting in almost complete blockade of ookinete conversion and oocyst development in the Δpbpp5 lines. This sexual development defect was rescued by crossing Δpbpp5 with the female defective Δpbs47 parasite line, but not with the male defective Δpbs48/45 line, thus confirming the essential function of the pbpp5 gene in male gamete fertility. Furthermore, the aforementioned PP1/PP2A inhibitors all had inhibitory effects on exflagellation of male gametocytes and ookinete conversion. In particular, endothall, a selective inhibitor of PP2A, completely blocked exflagellation and ookinete conversion at ~548.3 nM. This study elucidated an essential function of PbPP5 during male gamete development and fertility. |
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Keywords: | Corresponding authors at: Department of Immunology College of Basic Medical Sciences China Medical University No 77 Puhe Road Shenyang North New Area Shenyang Liaoning Province China Fax: +86 02423255291 (Y Cao) Department of Internal Medicine Morsani College of Medicine University of South Florida 3720 Spectrum Boulevard Suite 304 Tampa FL 33612-9415 USA (L Cui) Protein phosphatase Phosphorylation Male gametocyte Fertility Malaria |
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