Dataset Information

Phosphoinositide metabolism links cGMP-dependent protein kinase G to essential Ca²? signals at key decision points in the life cycle of malaria parasites.

ABSTRACT: Many critical events in the Plasmodium life cycle rely on the controlled release of Ca²? from intracellular stores to activate stage-specific Ca²?-dependent protein kinases. Using the motility of Plasmodium berghei ookinetes as a signalling paradigm, we show that the cyclic guanosine monophosphate (cGMP)-dependent protein kinase, PKG, maintains the elevated level of cytosolic Ca²? required for gliding motility. We find that the same PKG-dependent pathway operates upstream of the Ca²? signals that mediate activation of P. berghei gametocytes in the mosquito and egress of Plasmodium falciparum merozoites from infected human erythrocytes. Perturbations of PKG signalling in gliding ookinetes have a marked impact on the phosphoproteome, with a significant enrichment of in vivo regulated sites in multiple pathways including vesicular trafficking and phosphoinositide metabolism. A global analysis of cellular phospholipids demonstrates that in gliding ookinetes PKG controls phosphoinositide biosynthesis, possibly through the subcellular localisation or activity of lipid kinases. Similarly, phosphoinositide metabolism links PKG to egress of P. falciparum merozoites, where inhibition of PKG blocks hydrolysis of phosphatidylinostitol (4,5)-bisphosphate. In the face of an increasing complexity of signalling through multiple Ca²? effectors, PKG emerges as a unifying factor to control multiple cellular Ca²? signals essential for malaria parasite development and transmission.

SUBMITTER: Brochet M

PROVIDER: S-EPMC3942320 | biostudies-other | 2014 Mar

REPOSITORIES: biostudies-other

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Publications

Phosphoinositide metabolism links cGMP-dependent protein kinase G to essential Ca²⁺ signals at key decision points in the life cycle of malaria parasites.

Brochet Mathieu M Collins Mark O MO Smith Terry K TK Thompson Eloise E Sebastian Sarah S Volkmann Katrin K Schwach Frank F Chappell Lia L Gomes Ana Rita AR Berriman Matthew M Rayner Julian C JC Baker David A DA Choudhary Jyoti J Billker Oliver O

PLoS biology 20140304 3

Many critical events in the Plasmodium life cycle rely on the controlled release of Ca²⁺ from intracellular stores to activate stage-specific Ca²⁺-dependent protein kinases. Using the motility of Plasmodium berghei ookinetes as a signalling paradigm, we show that the cyclic guanosine monophosphate (cGMP)-dependent protein kinase, PKG, maintains the elevated level of cytosolic Ca²⁺ required for gliding motility. We find that the same PKG-dependent pathway operates upstream of the Ca²⁺ signals tha ...[more]

PMID: 24594931

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Project description:The invasion of erythrocytes by Plasmodium merozoites requires specific interactions between host receptors and parasite ligands. Parasite proteins that bind erythrocyte receptors during invasion are localized in apical organelles called micronemes and rhoptries. The regulated secretion of microneme and rhoptry proteins to the merozoite surface to enable receptor binding is a critical step in the invasion process. The sequence of these secretion events and the external signals that trigger release are not known. We have used time-lapse video microscopy to study changes in intracellular calcium levels in Plasmodium falciparum merozoites during erythrocyte invasion. In addition, we have developed flow cytometry based methods to measure relative levels of cytosolic calcium and study surface expression of apical organelle proteins in P. falciparum merozoites in response to different external signals. We demonstrate that exposure of P. falciparum merozoites to low potassium ion concentrations as found in blood plasma leads to a rise in cytosolic calcium levels through a phospholipase C mediated pathway. Rise in cytosolic calcium triggers secretion of microneme proteins such as the 175 kD erythrocyte binding antigen (EBA175) and apical membrane antigen-1 (AMA-1) to the merozoite surface. Subsequently, interaction of EBA175 with glycophorin A (glyA), its receptor on erythrocytes, restores basal cytosolic calcium levels and triggers release of rhoptry proteins. Our results identify for the first time the external signals responsible for the sequential release of microneme and rhoptry proteins during erythrocyte invasion and provide a starting point for the dissection of signal transduction pathways involved in regulated exocytosis of these key apical organelles. Signaling pathway components involved in apical organelle discharge may serve as novel targets for drug development since inhibition of microneme and rhoptry secretion can block invasion and limit blood-stage parasite growth.

Dataset Information

Phosphoinositide metabolism links cGMP-dependent protein kinase G to essential Ca²? signals at key decision points in the life cycle of malaria parasites.

Publications

Phosphoinositide metabolism links cGMP-dependent protein kinase G to essential Ca²⁺ signals at key decision points in the life cycle of malaria parasites.

Similar Datasets

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