Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.
Protein Analysis and Proteomics Laboratory, the Francis Crick Institute, London, United Kingdom.
PLoS Biol. 2019 Feb 22;17(2):e3000154. doi: 10.1371/journal.pbio.3000154. eCollection 2019 Feb.
Cyclic nucleotide signalling is a major regulator of malaria parasite differentiation. Phosphodiesterase (PDE) enzymes are known to control cyclic GMP (cGMP) levels in the parasite, but the mechanisms by which cyclic AMP (cAMP) is regulated remain enigmatic. Here, we demonstrate that Plasmodium falciparum phosphodiesterase β (PDEβ) hydrolyses both cAMP and cGMP and is essential for blood stage viability. Conditional gene disruption causes a profound reduction in invasion of erythrocytes and rapid death of those merozoites that invade. We show that this dual phenotype results from elevated cAMP levels and hyperactivation of the cAMP-dependent protein kinase (PKA). Phosphoproteomic analysis of PDEβ-null parasites reveals a >2-fold increase in phosphorylation at over 200 phosphosites, more than half of which conform to a PKA substrate consensus sequence. We conclude that PDEβ plays a critical role in governing correct temporal activation of PKA required for erythrocyte invasion, whilst suppressing untimely PKA activation during early intra-erythrocytic development.
环核苷酸信号转导是疟原虫分化的主要调节剂。磷酸二酯酶（PDE）酶已知可控制寄生虫中环鸟苷酸（cGMP）的水平，但 cAMP 调节的机制仍不清楚。在这里，我们证明恶性疟原虫磷酸二酯酶β（PDEβ）可水解 cAMP 和 cGMP，并且对红血细胞阶段的存活至关重要。条件性基因缺失导致红细胞入侵的显著减少和入侵的裂殖子的快速死亡。我们表明，这种双重表型是由 cAMP 水平升高和 cAMP 依赖性蛋白激酶（PKA）的过度激活引起的。对 PDEβ 缺失寄生虫的磷酸蛋白质组学分析表明，超过 200 个磷酸化位点的磷酸化水平增加了两倍以上，其中超过一半符合 PKA 底物的共识序列。我们得出结论，PDEβ在控制红细胞入侵所需的 PKA 的正确时间激活中起着关键作用，同时抑制了早期红内期发育过程中过早的 PKA 激活。
