Biogenesis of a mitochondrial DNA inheritance machinery in the mitochondrial outer membrane

et al. 2017

Preprint

Self Cite

In almost all eukaryotes mitochondria maintain their own genome. Despite the discovery more than 50 years ago still very little is known about how the genome is properly segregated during cell division.The protozoan parasite Trypanosoma brucei contains a single mitochondrion with a singular genome the kinetoplast DNA (kDNA). Electron microscopy studies revealed the tripartite attachment complex (TAC) to physically connect the kDNA to the basal body of the flagellum and to ensure proper segregation of the mitochondrial genome via the basal bodies movement, during cell cycle. Using super-resolution microscopy we precisely localize each of the currently known unique TAC components. We demonstrate that the TAC is assembled in a hierarchical order from the base of the flagellum towards the mitochondrial genome and that the assembly is not dependent on the kDNA itself. Based on biochemical analysis the TAC consists of several non-overlapping subcomplexes suggesting an overall size of the TAC exceeding 2.8 mDa. We furthermore demonstrate that the TAC has an impact on mitochondrial organelle positioning however is not required for proper organelle biogenesis or segregation. Significance StatementMitochondrial genome replication and segregation are essential processes in most eukaryotic cells.While replication has been studied in some detail much less is known about the molecular machinery required distribute the replicated genomes. Using super-resolution microscopy in combination with molecular biology and biochemistry we show for the first time in which order the segregation machinery is assembled and that it is assembled de novo rather than in a semi conservative fashion in the single celled parasite Trypanosoma brucei. Furthermore, we demonstrate that the mitochondrial genome itself is not required for assembly to occur. It seems that the physical connection of the mitochondrial genome to cytoskeletal elements is a conserved feature in most eukaryotes, however the molecular components are highly diverse.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Relative Order Of the Tac Proteinsmentioning

confidence: 98%

Section: Cell Culturementioning

confidence: 99%

Section: Cell Culturementioning

confidence: 99%

See 3 more Smart Citations

A molecular model of the mitochondrial genome segregation machinery inTrypanosoma brucei

Hoffmann

Käser

et al. 2017

Preprint

Self Cite

Molecular model of the mitochondrial genome segregation machinery in Trypanosoma brucei

Hoffmann

Käser

Proc. Natl. Acad. Sci. U.S.A.

et al. 2018

Self Cite

SignificanceMitochondrial genome replication and segregation are essential processes in most eukaryotic cells. While replication has been studied in some detail, much less is known about the molecular machinery required to distribute the replicated genomes. Using superresolution microscopy in combination with molecular biology and biochemistry, we show in which order the segregation machinery is assembled and that it is likely assembled de novo rather than in a semiconservative fashion in the single-celled parasite Trypanosoma brucei. Furthermore, we demonstrate that the mitochondrial genome itself is not required for assembly to occur. It seems that the physical connection of the mitochondrial genome to cytoskeletal elements is a conserved feature in most eukaryotes; however, the molecular components are highly diverse.

Characterization of the Novel Mitochondrial Genome Replication Factor MiRF172 inTrypanosoma brucei

Amodeo

Ochsenreiter

2017

Preprint

25All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. 35Detailed analysis suggests that MiRF172 is likely involved in the reattachment of replicated minicircles 36 to the kDNA disc. Furthermore, we provide evidence that the localization of the replication factor 37MiRF172 not only depends on the kDNA itself, but also on the mitochondrial genome segregation 38 machinery suggesting a tight interaction between the two essential entities.