A putative calcium-ATPase of the secretory pathway family may regulate calcium/manganese levels in the Golgi apparatus of Entamoeba histolytica

Abstract

Calcium regulates many cellular processes in protozoa, including growth, differentiation, programmed cell death, exocytosis, endocytosis, phagocytosis, fusion of the endosomes of distinct stages with phagosomes, fusion of phagosomes with lysosomes, and recycling the membrane. In Entamoeba histolytica, the protozoa responsible for human amoebiasis, calcium ions are essential for signaling pathways that lead to growth and development. In addition, calcium is crucial in the modulation of gene expression in this microorganism. However, there is scant information about the proteins responsible for regulating calcium levels in this parasite. In this work, we characterized a protein of E. histolytica that shows a close phylogenetic relationship with Ca pumps that belong to the family of secretory pathway calcium ATPases (SPCA), which for several organisms are located in the Golgi apparatus. The amoeba protein analyzed herein has several amino acid residues that are characteristic of SPCA members. By an immunofluorescent technique using specific antibodies and immunoelectron microscopy, the protein was detected on the membrane of some cytoplasmic vacuoles. Moreover, this putative calcium-ATPase was located in vacuoles stained with NBD C6-ceramide, a Golgi marker. Overall, the current findings support the hypothesis that the presently analyzed protein corresponds to the SPCA of E. histolytica.

An Entamoeba-Specific Mitosomal Membrane Protein with Potential Association to the Golgi Apparatus

“…It shows homology with the human cation-transporting ATPase 13A2 (NP_071372, with 28% identity and e-value of 1 × 10 −79 ), that is known as a causative gene for Kufor–Rakeb syndrome caused by lysosomal dysfunction [33]. Recently, this protein was annotated as a member of the secretory pathway calcium ATPases (SPCA) family as it exhibited close phylogenetic relationship to this protein family, demonstrated localization in vacuoles stained with NBD C6-ceramide, a fluorescent dye associated to the Golgi apparatus and subsequently named Eh SPCA [16]. The other candidates, EHI_051060 and EHI_030830, showed homology to pyruvate:ferredoxin oxidoreductase and plasma membrane calcium-transporting ATPase, respectively, but both have lower peptide counts detected from the protein sequencing analysis.…”

“…Here, we report another Entamoeba -specific mitosomal membrane protein predicted to possess five transmembrane domains, which we name Entamoeba transmembrane mitosomal protein of 30 kDa (ETMP30). It appears to interact with a cation-transporting P-type ATPase (EHI_065670) previously reported to be localized to vacuolar compartments that are postulated to be Golgi-like structures [16] in E. histolytica .…”

Golgi apparatus components in Entamoeba histolytica and Entamoeba dispar after monensin treatment

“…In addition, a proteomic study of E. histolytica endomembranes identified peptides and proteins matching glycosylation functions, usually performed within the Golgi apparatus (Perdomo et al, 2014). Finally, calcium levels in Golgi compartments are regulated by a calcium-ATPase that in E. histolytica colocalizes with NBD-6 ceramide-stained vacuoles (Rodríguez et al, 2018).…”

Entamoeba histolytica and pathogenesis: A calcium connection

“…More recently, 2 Ca 2 + -ATPases from E. histolytica (Eh), namely EhSPCA (secretory pathway calcium ATPase) and EhCCX (Ca 2+ /cation exchanger), have been identified. These are present on the membrane of some cytoplasmic vesicles [9,10]. Interestingly, overexpression of EhCCX enhanced the virulence and reduced the cell death of trophozoites [9].…”