Inorganic phosphate acquisition systems in Acanthamoeba castellanii and its relationships with energetic metabolism

Acanthamoeba castellanii is a free-living amoeba that is found in trophozoite and cyst forms in the environment. While trophozoites rely primarily on mitochondrial oxidative phosphorylation for ATP production, cysts exhibit metabolic adaptations that enable survival under adverse conditions, including anaerobic ATP synthesis. Inorganic phosphate (Pi) plays a central role in cellular bioenergetics, as it is required for ATP synthesis. Pi uptake is mediated by specific membrane transporters that are functionally coupled to ion gradients. Emerging data indicate that inorganic phosphate transport is tightly integrated with both aerobic and anaerobic energy metabolism in A. castellanii, influencing ATP production, substrate utilization, and cellular viability. In this review, we summarize current knowledge on inorganic phosphate transport systems in A. castellanii and discuss their relationship with energy metabolism in both trophozoites and cysts.