A unique phosphatidylinositol 4-phosphate 5-kinase is activated by ADP-ribosylation factor in Plasmodium falciparum

作者：Leber Werner^*; Skippen Alison; Fivelman Quinton L; Bowyer Paul W; Cockcroft Shamshad; Baker David A

来源：International Journal for Parasitology, 2009, 39(6): 645-653.

DOI：10.1016/j.ijpara.2008.11.015

• Plasmodium
• Phosphatidylinositol 4-phosphate 5-kinase
• Neuronal calcium sensor protein
• ADP-ribosylation factor
• Protein trafficking
• Cytoskeleton

In eukaryotes, calcium signalling has been linked to hydrolysis of the phosphatidylinositol 4,5-bisphosphate (PtdIns(4,S)P(2)). The final enzyme in the synthesis of this phosphoinositide, a Type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K), is activated by the small G protein ADP-ribosylation factor I (ARF1). In mammals, the ARF-PIP5K pathway is a key regulator of cell motility, secretion and cell signalling. We report the characterisation of a unique, putative bifunctional PIP5K in the human malaria parasite Plasmodium falciparum. The protein comprises a C-terminal, functional PIP5K domain with catalytic specificity for phosphatidylinositol 4-phosphate. The recombinant enzyme is activated by ARF1 but not phosphatidic acid. The protein also incorporates an unusual N-terminal domain with potential helix-loop-helix EF-hand-like motifs that is a member of the neuronal calcium sensor family (NCS). Intriguingly, NCS-1 has been shown to stimulate phosphatidylinositol 4-phosphate synthesis by activating mammalian and yeast phosphatidylinositol 4-kinase beta in vitro in a calcium-dependent manner. The unexpected physical attachment of an NCS-like domain to the plasmodial PIP5K might reflect a unique functional link between the calcium and PtdIns(4,5)P(2) pathways allowing modulation of PtdIns(4,5)P(2) production in response to changes in intracellular calcium concentrations within the parasite.

• 出版日期2009-5