Protein interactions and regulatory role of low-molecular-weight protein tyrosine phosphatase in Entamoeba histolytica virulence.

Amoebiasis is a gastrointestinal infection caused by the protozoan parasite Entamoeba histolytica (E. histolytica, Eh) and remains one of the leading parasitic causes of human mortality worldwide. Invasive intestinal disease may present with abdominal cramping, abdominal pain, watery or bloody diarrhea, and weight loss. Understanding the factors that modulate parasite virulence is therefore essential to elucidate disease pathogenesis. The E. histolytica genome encodes two low-molecular-weight protein tyrosine phosphatases (LMW-PTPs), EhLMW-PTP1 and EhLMW-PTP2, whose roles in parasite virulence remain poorly understood. Here, we investigated the molecular interactions of EhLMW-PTP2 using in vitro assays with recombinant wild-type protein and its catalytic mutant. Pull-down assays and co-immunoprecipitation coupled with LC-MS/MS were performed to identify candidate proteins associated with EhLMW-PTP2 following fibronectin stimulation. Selected interactors, including EhCP5 and EhCBP, were further analyzed in trophozoites overexpressing EhLMW-PTP2, where reduced transcript and protein levels were observed. Parasites overexpressing EhLMW-PTP2 exhibited reduced migratory capacity and caused less liver damage in infected hamsters, consistent with previous observations of decreased phagocytosis and cytopathic activity. Notably, these effects were observed independently of catalytic site integrity in vivo. Our results indicate that EhLMW-PTP2 is associated with protein interaction networks that include factors linked to transcriptional processes, cytoskeletal organization, and vesicular trafficking. However, these findings should be interpreted as associations, and their contribution to the reduced virulence phenotype remains to be determined.