DNA segregation in mitochondria and beyond: insights from the trypanosomal tripartite attachment complex.

The single unit nature of the mitochondrial genome (kinetoplast DNA; kDNA) of trypanosomes requires precise mechanisms that guarantee the segregation of the duplicated kDNA during cytokinesis. Segregation of the duplicated kDNA during cytokinesis depends on the tripartite attachment complex (TAC), which physically links the basal body (BB) of the flagellum with the kDNA. Much progress has been made in identifying the molecular core subunits of the TAC and how they interact with each other, allowing formulation of a model of TAC architecture that explains how the TAC connects the BB across the mitochondrial membranes with the kDNA. Recent studies highlight how individual TAC subunits are imported into mitochondria, sorted to, and integrated into, the TAC, illustrating the central role of the mitochondrial outer membrane TAC module in the assembly process. A comparative analysis between the TAC and the mitotic spindle reveals conserved features and concepts shared between these DNA segregation complexes. The tripartite attachment complex (TAC) of the single mitochondrion of trypanosomes allows precise segregation of its single nucleoid mitochondrial genome during cytokinesis. It couples the segregation of the duplicated mitochondrial genome to the segregation of the basal bodies of the flagella. Here, we provide a model of the molecular architecture of the TAC that explains how its eight essential subunits connect the basal body, across the mitochondrial membranes, with the mitochondrial genome. We also discuss how the TAC subunits are imported into the mitochondrion and how they assemble to form a new TAC. Finally, we present a comparative analysis of the trypanosomal TAC with open and closed mitotic spindles, which reveals conserved concepts between these diverse DNA segregation systems. The tripartite attachment complex (TAC) of the single mitochondrion of trypanosomes allows precise segregation of its single nucleoid mitochondrial genome during cytokinesis. It couples the segregation of the duplicated mitochondrial genome to the segregation of the basal bodies of the flagella. Here, we provide a model of the molecular architecture of the TAC that explains how its eight essential subunits connect the basal body (BB), across the mitochondrial membranes, with the mitochondrial genome. We also discuss how the TAC subunits are imported into the mitochondrion and how they assemble to form a new TAC. Finally, we present a comparative analysis of the trypanosomal TAC with open and closed mitotic spindles, which reveals conserved concepts between these diverse DNA segregation systems. [ABSTRACT FROM AUTHOR]