摘要：Under anaerobic environments, the mitochondria have undergone remarkable reduction and transformation into highly reduced structures, referred as m itochondrion- r elated o rganelles (MROs), which include mitosomes and hydrogenosomes. In agreement with the concept of reductive evolution, mitosomes of Entamoeba histolytica lack most of the components of the TOM ( t ranslocase of the o uter m itochondrial membrane) complex, which is required for the targeting and membrane translocation of preproteins into the canonical aerobic mitochondria. Here we showed, in E. histolytica mitosomes, the presence of a 600-kDa TOM complex composed of Tom40, a conserved pore-forming subunit, and Tom60, a novel lineage-specific receptor protein. Tom60, containing multiple tetratricopeptide repeats, is localized to the mitosomal outer membrane and the cytosol, and serves as a receptor of both mitosomal matrix and membrane preproteins. Our data indicate that Entamoeba has invented a novel lineage-specific shuttle receptor of the TOM complex as a consequence of adaptation to an anaerobic environment.
