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PfCDPK7 is an atypical member of the calcium‐dependent protein kinase (CDPK) family and is crucial for the development of Plasmodium falciparum. However, the mechanisms whereby PfCDPK7 regulates parasite development remain unknown. Here, we perform quantitative phosphoproteomics and phospholipid analysis and find that PfCDPK7 promotes phosphatidylcholine (PC) synthesis by regulating two key enzymes involved in PC synthesis, phosphoethanolamine‐N‐methyltransferase (PMT) and ethanolamine kinase (EK). In the absence of PfCDPK7, both enzymes are hypophosphorylated and PMT is degraded. We further find that PfCDPK7 interacts with 4'‐phosphorylated phosphoinositides (PIPs) generated by PI4‐kinase. Inhibition of PI4K activity disrupts the vesicular localization PfCDPK7. P. falciparum PI4‐kinase, PfPI4K is a prominent drug target and one of its inhibitors, MMV39048, has reached Phase I clinical trials. Using this inhibitor, we demonstrate that PfPI4K controls phospholipid biosynthesis and may act in part by regulating PfCDPK7 localization and activity. These studies not only unravel a signaling pathway involving PfPI4K/4'‐PIPs and PfCDPK7 but also provide novel insights into the mechanism of action of a promising series of candidate anti‐malarial drugs. Synopsis: PfPI4K and PfCDPK7 regulate the development of the malaria parasite Plasmodium falciparum by promoting phospholipid biosynthesis. PI4‐Kinase regulates the localization and activity of protein kinase PfCDPK7 via 4'‐PIPs.PfCDPK7 promotes phosphatidylcholine (PC) synthesis by targeting key enzymes involved in the synthesis of this phospholipid.PI4‐K promotes PL biosynthesis in P. falciparum and its regulation of PfCDPK7 activity contributes to this process. [ABSTRACT FROM AUTHOR]

Autophagy is a degradation process, wherein long‐lived proteins, damaged organelles, and protein aggregates are degraded to maintain cellular homeostasis. Upon starvation, 5′‐AMP‐activated protein kinase (AMPK) initiates autophagy. We show that ampkα− cells exhibit 50% reduction in pinocytosis and display defective phagocytosis. Re‐expression of AMPKα in ampkα− cells co‐localizes with red fluorescence protein‐tagged bacteria. The ampkα− cells show reduced cell survival and autophagic flux under basal and starvation conditions. Co‐immunoprecipitation studies show conservation of the AMPK–ATG1 axis in basal autophagy. Computational analyses suggest that the N‐terminal region of DdATG1 is amenable for interaction with AMPK. Furthermore, β‐actin was found to be a novel interacting partner of AMPK, attributed to the alteration in macropinocytosis and phagocytosis in the absence of AMPK. Additionally, ampkα− cells exhibit enhanced poly‐ubiquitinated protein levels and allied large ubiquitin‐positive protein aggregates. Our findings suggest that AMPK provides links among pinocytosis, phagocytosis, autophagy, and is a requisite for basal autophagy in Dictyostelium. [ABSTRACT FROM AUTHOR]

Starved Dictyostelium cells aggregate into groups of nearly 10 5 cells. AMPK is a highly conserved serine/threonine protein kinase consisting of a catalytic and two regulatory subunits. As multi-cellular development in Dictyostelium is initiated upon starvation, we explored the role of the energy sensor, AMPK, which shows significant similarity to human AMPK and is expressed throughout development. Deletion of the ampkα gene results in the formation of numerous small-sized aggregates that develop asynchronously to form few fruiting bodies with small sori and long stalks. On the other hand, ampkα OE cells form fruiting bodies with small stalks and large sori when compared with wild-type, Ax2. A minimum of 5% ampkα - cells in a chimaera with Ax2 cells was sufficient to reduce the aggregate size. Also, the conditioned media collected from ampkα - cells triggered Ax2 cells to form smaller aggregates. The starved ampkα - cells showed low glucose levels and formed large aggregates when glucose was supplied exogenously. Interestingly, ampkα - cells exhibit abnormal cell-type patterning with increased prestalk region and a concomitant reduction of prespore region. In addition, there was a loss of distinct prestalk/prespore boundary in the slugs., (© 2017 The Authors.)

Essential oil of Mentha spicata L. var. viridis 'Ganga', an indigenously developed variety, was chemically profiled using various gas chromatographic techniques. Piperitenone oxide was characterized as the most exclusive constituent (69.7%) along with a new C₃-oxygenated p-menthane alcohol,- diosphenolene (1.6%). Enantiomeric discrimination revealed (4S)-(-)-limonene, (R)-(-)-linalool and (lS,2S)-(+)-piperitenone oxide as predominant enantiomers. The oil contained mainly C₃-oxygenated p-menthane monoterpenoids, which are distinctive of peppermint, instead of the characteristic C₆-oxygenated class of spearmint. The present findings will aid in understanding the pathway and cause of C₃-oxygenation in a spearmint taxon. The essential oil and pure piperitenone oxide showed growth inhibiting properties and thus, may be utilized in antifungal preparations for disease management of medicinal and aromatic plants.