Sulfate Activation in Mitosomes Plays an Important Role in the Proliferation of Entamoeba histolytica

Abstract

Mitochondrion-related organelles, mitosomes and hydrogenosomes, are found in a phylogenetically broad range of organisms. Their components and functions are highly diverse. We have previously shown that mitosomes of the anaerobic/microaerophilic intestinal protozoan parasite Entamoeba histolytica have uniquely evolved and compartmentalized a sulfate activation pathway. Although this confined metabolic pathway is the major function in E. histolytica mitosomes, their physiological role remains unknown. In this study, we examined the phenotypes of the parasites in which genes involved in the mitosome functions were suppressed by gene silencing, and showed that sulfate activation in mitosomes is important for sulfolipid synthesis and cell proliferation. We also demonstrated that both Cpn60 and unusual mitochondrial ADP/ATP transporter (mitochondria carrier family, MCF) are important for the mitosome functions. Immunoelectron microscopy demonstrated that the enzymes involved in sulfate activation, Cpn60, and mitochondrial carrier family were differentially distributed within the electron dense, double membrane-bounded organelles. The importance and topology of the components in E. histolytica mitosomes reinforce the notion that they are not “rudimentary” or “residual” mitochondria, but represent a uniquely evolved crucial organelle in E. histolytica.

Novel TPR-containing subunit of TOM complex functions as cytosolic receptor for Entamoeba mitosomal transport

“…2b). Proteinase K sensitivity increased in the order of APSK-HA, AAC-HA (inner membrane protein2327)/Tom40-HA, and Tom60-HA (Fig. 2b).…”

“…The importance of mitosomal matrix proteins, i.e., ATP sulfurylase (AS; XP_653570), APSK, inorganic pyrophosphatase (IPP; XP_649445), Cpn60, and AAC for E. histolytica proliferation was previously verified by gene silencing27. To demonstrate the biological importance of the mitosomal import machinery per se, we established E. histolytica strains in which EhTom40 and EhTom60 genes were silenced.…”

“…For gene silencing, a 400-bp fragment corresponding to the amino terminus of Tom40 and Tom60 was PCR-amplified with appropriate primers (Supplementary Table S5). Restriction-digested fragments were ligated into Stu I/ Sac I double-digested psAP-2-Gunma plasmid27.…”

Changes in ultrastructural features of the foraminifera Ammonia spp. in response to anoxic conditions: Field and laboratory observations

“…(phylotype T6) (Nomaki et al, 2016), as 34 S-labeled sulfate was incorporated into the electron dense bodies in specimens incubated in dysoxic conditions. Those authors conclude that the sulfate activation pathway may be related to foraminiferal dormancy or encystment under anoxia in a manner similar to Entamoeba histolytica (Mi-ichi et al, 2011(Mi-ichi et al, , 2015.…”

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

“…The Entamoeba mitosome possesses a mitochondrial-type ADP/ATP translocator (80); its function is still under investigation (520). Recently, the enzymes of sulfate activation were localized to the mitosomes of Entamoeba (332,333), providing a new perspective on mitosomal functions. Other possible functions might have to do with FeS cluster maturation and hydroperoxide detoxification via the rubrerythrin system (302).…”