Rapid metabolic reprogramming mediated by the AMP-activated protein kinase during the lytic cycle of Toxoplasma gondii

Abstract

The ubiquitous pathogen Toxoplasma gondii has a complex lifestyle with different metabolic activities at different stages that are intimately linked to the parasitic environments. Here we identified the eukaryotic regulator of cellular homeostasis AMP-activated protein kinase (AMPK) in Toxoplasma and discovered its role in metabolic programming during parasite’s lytic cycle. The catalytic subunit AMPKα is quickly phosphorylated after the release of intracellular parasites to extracellular environments, driving energy-producing catabolism to power parasite motility and invasion into host cells. Once inside host cells, AMPKα phosphorylation is reduced to basal level to promote a balance between energy production and biomass synthesis, allowing robust parasite replication. AMPKγ depletion abolishes AMPKα phosphorylation and suppresses parasite growth, which can be partially rescued by overexpressing wildtype AMPKα but not the phosphorylation mutants. Thus, through the cyclic reprogramming by AMPK, the parasites’ metabolic needs at each stage are satisfied and the lytic cycle progresses robustly.

Keeping FIT: Iron-mediated post-transcriptional regulation inToxoplasma gondii

“…We observed 1197 transcripts with higher abundance in parasites cultured in low iron conditions compared to untreated parasites, whilst just 44 were downregulated (log 2 fold change £-2, adjusted p -value (padj) < 0.05) ( Table S1 ). This bias towards upregulation of transcripts was unexpected and was not seen upon oxidative stress induction (Augusto, 2021) or upon downregulation of an essential metabolic regulator (Li et al ., 2023).…”

The α subunit of AMP‐activated protein kinase is critical for the metabolic success and tachyzoite proliferation of Toxoplasma gondii

“…Our previous results showed that the kinase domains of Tg KIN and Tg AMPKα have significant sequence similarities, with 51% and 72% amino acid sequence identity and similarity respectively (Li et al., 2023 ). Outside the kinase domains, the two proteins share little similarities (Figure S1A ).…”

“…Plaque, two‐colour invasion, replication, and bradyzoite induction experiments were performed as described previously (Li et al., 2023 ; Xia et al., 2018 ; Yang, Yin, et al., 2022 ). All strains were pretreated with or without rapamycin for 48 h to induce the excision of floxed AMPKα before phenotypic assessment, as indicated in figure legends.…”

“…We recently discovered that the AMPK complex in T. gondii has critical roles in regulating the metabolic and developmental programmes of the parasites (Li et al., 2023 ; Yang, Yang, et al., 2022 ). AMPK is a conserved regulator of metabolic homeostasis found in most eukaryotes (Herzig & Shaw, 2018 ).…”

“…Our previous studies found that T. gondii encodes a single canonical AMPK complex and a KIN kinase. AMPKγ depletion abolished AMPKα phosphorylation and inhibited parasite growth, which could be partially rescued by overexpression of the wild‐type but not the phosphorylation defective mutant of AMPKα, suggesting that AMPK‐mediated metabolic reprogramming is critical for the proliferation of the Toxoplasma tachyzoites (Li et al., 2023 ). In addition, the phosphorylation level of AMPKα was greatly increased in alkaline‐stressed parasites, but this effect was not observed in mutants lacking TgAMPKβ.…”