The Glycosylphosphatidylinositol Transamidase Complex Subunit PbGPI16 of Plasmodium berghei Is Important for Inducing Experimental Cerebral Malaria

Abstract

In animal models of experimental cerebral malaria (ECM), the glycosylphosphatidylinositols (GPIs) and GPI anchors are the major factors that induce nuclear factor kappa B (NF-κB) activation and proinflammatory responses, which contribute to malaria pathogenesis. GPIs and GPI anchors are transported to the cell surface via a process called GPI transamidation, which involves the GPI transamidase (GPI-T) complex. In this study, we showed that GPI16, one of the GPI-T subunits, is highly conserved among species. Genetic knockout of () in the rodent malaria parasite strain ANKA led to a significant reduction of the amounts of GPIs in the membranes of merozoites, as well as surface display of several GPI-anchored merozoite surface proteins. Compared with the wild-type parasites, parasites in C57BL/6 mice caused much less NF-κB activation and elicited a substantially attenuated T helper type 1 response. As a result, mutant-infected mice displayed much less severe brain pathology, and considerably fewer mutant-infected mice died from ECM. This study corroborated the GPI toxin as a significant inducer of ECM and further suggested that vaccines against parasite GPIs may be a promising strategy to limit the severity of malaria.

Unveiling the Sugary Secrets of Plasmodium Parasites

“…Further downstream, the GPI transamidase complex can link proteins to the GPI anchor. Notably, mice infected with P. berghei carrying a knockout of the PbGPI16 subunit of the GPI transamidase showed less inflammation, and fewer mice challenged with this knockout developed cerebral malaria compared to the wildtype strain (Liu et al, 2018). These findings corroborate the crucial role of Plasmodium GPIs in inflammation and the development of severe malaria.…”

A conserved malaria parasite antigen Pb22 plays a critical role in male gametogenesis inPlasmodium berghei

“…After washing with PBS, the parasites without membrane permeabilisation were treated with 0.1% Triton X‐100 and then blocked with 3% BSA/PBS for 60 min. Subsequently, parasites were co‐incubated with rabbit antisera against PbMSP1 (1:500), P47 (1:500), α‐tubulin II (1:500), SET (1:500) and PSOP25 (1:500) as stage‐specific markers for schizonts, female gametocytes/gametes, male gametocytes/gametes, nucleus and ookinetes, respectively (Liu et al, 2018, 2019; Molina‐Cruz, Canepa, & Barillas‐Mury, 2017; Pace et al, 2006; Zheng et al, 2017). After three washes with PBS, Alexa Fluor‐488‐conjugated goat anti‐mouse IgG antibodies (1:500; Invitrogen, A32723) and Alexa Fluor‐555‐conjugated goat anti‐rabbit IgG antibodies (1:500; Abcam, ab50078) were added and incubated for 1 hr.…”

The consensus Nglyco‐X‐S/T motif and a previously unknown Nglyco‐N‐linked glycosylation are necessary for growth and pathogenicity of Phytophthora

“…The GPI transamidase subunits GPI8, GPI16, and GAA1 form three‐component core sub‐complexes in S. cerevisiae , which is conserved in many species (Meyer et al ., 2000). Structural modelling suggests that GPI16 may present the substrate protein to GPI8p, and deletion of GPI16 gene in Plasmodium berghei reduces GPIs and GPI‐anchored proteins in parasite membranes (Liu et al ., 2018). Further work is needed to determine whether N ‐glycosylation of GPI16 affects the biosynthesis of GPIs in Phytophthora .…”