TimX, a novel player in protein import across the inner mitochondrial membrane of T. brucei

Harsman, Anke Judith (25 April 2015). TimX, a novel player in protein import across the inner mitochondrial membrane of T. brucei (Unpublished). In: Kinetoplastid Molecular Cell Biology Meeting KMCB 2015. Woods Hole, MA, USA. 25.04.2015 - 29.04.2015.

Mitochondrial protein import is an essential function of the unique mitochondrion in T. brucei as roughly 1000 different nuclear encoded proteins need to be correctly localized to their mitochondrial subcompartment. For this reason the responsible import machinery is expected to be similarly complex as in other Eukaryotes. This was recently demonstrated for the translocation machinery in the outer mitochondrial membrane. In contrast, the composition of the inner membrane import machinery and the exact molecular pathway(s) taken by various substrates are still ill-defined. To elucidate this further, we performed a pulldown analysis of epitope tagged TbTim17 in combination with quantitative mass spectrometry. By this we identified novel components of the mitochondrial import machinery in trypanosomes. One of these, TimX, is an essential mitochondrial membrane protein of 42 kDa that is unique to kinetoplastids. This protein migrates on Blue Native PAGE in a high molecular weight complex similar to TbTim17. Ablation of either of the two proteins leads to a destabilization of the complex containing the other protein. Furthermore, its involvement in protein import could be demonstrated by in vivo and in vitro protein import assays. This corroborates that TimX together with TbTim17 forms a protein import complex in the inner mitochondrial membrane. As TbTim17 the TimX protein was subjected to pulldown analysis in combination with quantitative mass spectrometry. The overlap of candidates defined by these two sets of IPs likely defines further components of the inner membrane translocase which are presently being analyzed. In summary our study on novel components of the trypanosome mitochondrial protein import system gives us fascinating new insights into evolution of the mitochondrion.

Item Type:

Conference or Workshop Item (Poster)


08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Harsman, Anke Judith


500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry




Christina Schüpbach

Date Deposited:

18 Jan 2016 14:30

Last Modified:

18 Jan 2016 14:30



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