TgPL2, a patatin‐like phospholipase domain‐containing protein, is involved in the maintenance of apicoplast lipids homeostasis in Toxoplasma

Abstract

Patatin-like phospholipases are involved in numerous cellular functions, including lipid metabolism and membranes remodeling. The patatin-like catalytic domain, whose phospholipase activity relies on a serine-aspartate dyad and an anion binding box, is widely spread among prokaryotes and eukaryotes. We describe TgPL2, a novel patatin-like phospholipase domain-containing protein from the parasitic protist Toxoplasma gondii. TgPL2 is a large protein, in which the key motifs for enzymatic activity are conserved in the patatin-like domain. Using immunofluorescence assays and immunoelectron microscopy analysis, we have shown that TgPL2 localizes to the apicoplast, a non-photosynthetic plastid found in most apicomplexan parasites. This plastid hosts several important biosynthetic pathways, which makes it an attractive organelle for identifying new potential drug targets. We thus addressed TgPL2 function by generating a conditional knockdown mutant and demonstrated it has an essential contribution for maintaining the integrity of the plastid. In absence of TgPL2, the organelle is rapidly lost and remaining apicoplasts appear enlarged, with an abnormal accumulation of membranous structures, suggesting a defect in lipids homeostasis. More precisely, analyses of lipid content upon TgPL2 depletion suggest this protein is important for maintaining levels of apicoplast-generated fatty acids, and also regulating phosphatidylcholine and lysophosphatidylcholine levels in the parasite.

Phospholipases during membrane dynamics in malaria parasites

“…4, Table 2). While currently no experimental data are available on the Plasmodium PLPs, a new study in the apicomplexan model parasite Toxoplasma gondii describes an essential role for the PLP TgPL2 (a homolog of Pf3D7_1358000) in maintenance of apicoplast integrity (Lévêque et al, 2017). In the absence of TgPL2, the plastid is rapidly lost and the remaining apicoplasts appear enlarged with abnormal accumulations of membranous structures (Lévêque et al, 2017).…”

Patatin‐like phospholipases in microbial infections with emerging roles in fatty acid metabolism and immune regulation by Apicomplexa

“…). Recently, TgPL2 was shown to be critical in maintaining membrane integrity of the apicoplast (Lévêque et al ., ). Lipid analysis revealed that TgPL2 is important for maintaining levels of apicoplast‐generated fatty acids and regulating PC and LPC levels in the parasite.…”

“…Additionally, compounds identified as potent inhibitors of ExoU PLA 2 activity did not inhibit the activity of mammalian‐derived PLA 2 s (Lee et al ., ). These parasite PLPs will likely be excellent drug targets as TgPL2 has already been characterized as a critical gene to parasite growth and replication (Lévêque et al ., ). Treatment of T. gondii with atglistatin, an inhibitor of ATGL, led to a decrease in parasite replication proportional to drug concentration and disorganization of the parasites within the PV.…”

A patatin‐like phospholipase functions during gametocyte induction in the malaria parasite Plasmodium falciparum

“…All PNPLAs exhibit a catalytic Ser-Asp dyad with the serine residue being embedded within the conserved penta-peptide Gly-Xaa-Ser-Xaa-Gly (GXSXG; reviewed in Arpigny & Jaeger, 1999; Banerji & Flieger, 2004;Ramanadham et al, 2015). Via their phospholipase A 2 (PLA 2 ) activity, PNPLAs are able to generate lysophospholipids and fatty acids, including polyunsaturated fatty acids, which are either further processed within the lipid metabolism pathway or which may act as signalling molecules (Lévêque et al, 2017;reviewed in Kienesberger et al, 2009;Ramanadham et al, 2015;Wilson & Knoll, 2018).…”

“…Such delayed maturation may eventually result in defective gametogenesis, if not fully matured gametocytes have been used in the exflagellation and RBC egress assays.PNPLAs can also be found in the Apicomplexan parasite Toxoplasma gondii; here, three of the roughly six annotated PNPLAs have meanwhile been functionally characterised. The two PNPLAs TgPL1and TgPLA 2 localize to vesicles and are discharged upon immune stress and during invasion, while TgPL2 is crucial for apicoplast integrity(Cassaing et al, 2000;Lévêque et al, 2017;Mordue, Scott- Weathers, Tobin, & Knoll, 2007; reviewed in Tobin & Knoll, 2012). In addition, in other eukaryotes important functions were assigned to PNPLAs.…”