The Essentials of Protein Import in the Degenerate Mitochondrion of Entamoeba histolytica
Figure 4
A mitochondrial Tom40 in Entamoeba histolytica.
(A) A representative figure from the CLANS analysis of a data set containing 79 Tom40 sequences (green dots), 137 VDAC (red dots) sequences and the EhTom40 sequence (blue dot). A P-value threshold of 10−82 was used to give complete separation of the VDAC and Tom40 clusters. Tom40 and VDAC sequences from D. discoideum, as the closest relative in the dataset, are highlighted (orange). (B) The alignment shows the C-terminal β-strand from various Tom40 homologues. The motif for the general import signal for mitochondrial β-barrel proteins is highlighted, P-polar residue, G-glycine residue, H-hydrophobic residue [48]. (C) The C-terminal GFP fusion of EhTom40 in yeast cells (green), the yeast mitochondria stained with Mitotracker red (red). The merged image demonstrates the co-localization of EhTom40 with the mitochondrial compartment. DIC – differential contrast (Nomarski). (D) S. cerevisiae Δ tom40 mutants, carrying a counterselectable TOM40 gene and expressing either S. cerevisiae Tom40 (ScTom40) or EhTom40 were plated onto 5-FOA media to select against the covering plasmid. Cells were incubated for 4 days at 30°C and only strain expressing ScTom40 was viable.