Assessment of lytic cycle and the impact of a gene deletion using 3D label-free optical diffraction holotomography.

is a widespread single-celled intracellular eukaryotic apicomplexan protozoan parasite primarily associated with mammalian foetal impairment and miscarriage, including in humans. Is estimated that approximately one third of the human population worldwide is infected by this parasite. Here we used cutting-edge, label-free 3D quantitative optical diffraction holotomography to capture and evaluate the lytic cycle (invasion, proliferation and egress) in real-time based on the refractive index distribution.

A single point mutation in the Bemisia tabaci cytochrome-P450 CYP6CM1 causes enhanced resistance to neonicotinoids.

The tobacco whitefly, Bemisia tabaci, is a polyphagous crop pest which causes high levels of economic damage across the globe. Insecticides are often required for the effective control of this species, among which the neonicotinoid class have been particularly widely used. Deciphering the mechanisms responsible for resistance to these chemicals is therefore critical to maintain control of B.

Illuminating Host-Parasite Interaction at the Cellular and Subcellular Levels with Infrared Microspectroscopy.

() is an opportunistic protozoan that can cause brain infection and other serious health consequences in immuno-compromised individuals. This parasite has a remarkable ability to cross biological barriers and exploit the host cell microenvironment to support its own survival and growth. Recent advances in label-free spectroscopic imaging techniques have made it possible to study biological systems at a high spatial resolution.

Antileishmanial Chemotherapy through Clemastine Fumarate Mediated Inhibition of the Inositol Phosphorylceramide Synthase.

Current chemotherapeutics for leishmaniasis have multiple deficiencies, and there is a need for new safe, efficacious, and affordable medicines. This study describes a successful drug repurposing approach that identifies the over-the-counter antihistamine, clemastine fumarate, as a potential antileishmanial drug candidate. The screening for inhibitors of the sphingolipid synthase (inositol phosphorylceramide synthase, IPCS) afforded, following secondary screening against (Lmj) promastigotes, 16 active compounds.

Ceramides bind VDAC2 to trigger mitochondrial apoptosis.

Ceramides draw wide attention as tumor suppressor lipids that act directly on mitochondria to trigger apoptotic cell death. However, molecular details of the underlying mechanism are largely unknown. Using a photoactivatable ceramide probe, we here identify the voltage-dependent anion channels VDAC1 and VDAC2 as mitochondrial ceramide binding proteins.

Tamoxifen inhibits the biosynthesis of inositolphosphorylceramide in Leishmania.

Previous work from our group showed that tamoxifen, an oral drug that has been in use for the treatment of breast cancer for over 40 years, is active both in vitro and in vivo against several species of Leishmania, the etiological agent of leishmaniasis. Using a combination of metabolic labeling with [H]-sphingosine and myo-[H]-inositol, alkaline hydrolysis, HPTLC fractionations and mass spectrometry analyses, we observed a perturbation in the metabolism of inositolphosphorylceramides (IPCs) and phosphatidylinositols (PIs) after treatment of L. amazonensis promastigotes with tamoxifen, with a significant reduction in the biosynthesis of the major IPCs (composed of d16:1/18:0-IPC, t16:0/C18:0-IPC, d18:1/18:0-IPC and t16:0/20:0-IPC) and PIs (sn-1-O-(C)alkyl -2-O-(C)acylglycerol-3-HPO-inositol and sn-1-O-(C)acyl-2-O-(C)acylglycerol-3-HPO-inositol) species.

A search for ceramide binding proteins using bifunctional lipid analogs yields CERT-related protein StarD7.

Ceramides are central intermediates of sphingolipid metabolism with dual roles as mediators of cellular stress signaling and mitochondrial apoptosis. How ceramides exert their cytotoxic effects is unclear and their poor solubility in water hampers a search for specific protein interaction partners. Here, we report the application of a photoactivatable and clickable ceramide analog, pacCer, to identify ceramide binding proteins and unravel the structural basis by which these proteins recognize ceramide.

Everybody needs sphingolipids, right! Mining for new drug targets in protozoan sphingolipid biosynthesis.

Sphingolipids (SLs) are an integral part of all eukaryotic cellular membranes. In addition, they have indispensable functions as signalling molecules controlling a myriad of cellular events. Disruption of either the de novo synthesis or the degradation pathways has been shown to have detrimental effects.

Switching head group selectivity in mammalian sphingolipid biosynthesis by active-site-engineering of sphingomyelin synthases.

SM is a fundamental component of mammalian cell membranes that contributes to mechanical stability, signaling, and sorting. Its production involves the transfer of phosphocholine from phosphatidylcholine onto ceramide, a reaction catalyzed by SM synthase (SMS)1 in the Golgi and SMS2 at the plasma membrane. Mammalian cells also synthesize trace amounts of the SM analog, ceramide phosphoethanolamine (CPE), but the physiological relevance of CPE production is unclear.

ER residency of the ceramide phosphoethanolamine synthase SMSr relies on homotypic oligomerization mediated by its SAM domain.

SMSr/SAMD8 is an ER-resident ceramide phosphoethanolamine synthase with a critical role in controlling ER ceramides and suppressing ceramide-induced apoptosis in cultured cells. SMSr-mediated ceramide homeostasis relies on the enzyme's catalytic activity as well as on its N-terminal sterile α-motif or SAM domain. Here we report that SMSr-SAM is structurally and functionally related to the SAM domain of diacylglycerol kinase DGKδ, a central regulator of lipid signaling at the plasma membrane.

Switching head group selectivity in mammalian sphingolipid biosynthesis by active-site engineering of sphingomyelin synthases.

SM is a fundamental component of mammalian cell membranes that contributes to mechanical stability, signaling, and sorting. Its production involves the transfer of phosphocholine from phosphatidylcholine onto ceramide, a reaction catalyzed by SM synthase (SMS) 1 in the Golgi and SMS2 at the plasma membrane. Mammalian cells also synthesize trace amounts of the SM analog ceramide phosphoethanolamine (CPE), but the physiological relevance of CPE production is unclear.