Characterization of the Novel Mitochondrial Genome Replication Factor MiRF172 in Trypanosoma brucei

The unicellular parasite Trypanosoma brucei harbors one individual mitochondrial organelle with a singular genome the kinetoplast DNA or kDNA. The kDNA largely consists of concatenated minicircles and a few maxicircles that are also interlocked into the kDNA disc. More than 30 proteins involved in kDNA replication have been described, however several mechanistic questions are only poorly understood. Here, we describe and characterize MiRF172, a novel mitochondrial genome replication factor, which is essential for proper cell growth and kDNA maintenance. Using super-resolution microscopy, we localize MiRF172 to the antipodal sites of the kDNA. We demonstrate that depletion of MiRF172 leads to continuous loss of mini- and maxicircles during the cell division cycle. Detailed analysis suggests that MiRF172 is likely involved in the reattachment of replicated minicircles to the kDNA disc. Furthermore, we provide evidence that the localization of the replication factor MiRF172 not only depends on the kDNA itself, but also on the mitochondrial genome segregation machinery suggesting a tight interaction between the two essential entities.\n\nSummary StatementMiRF172 is a novel protein involved in the reattachment of replicated minicircles in Trypanosoma brucei, which requires the mitochondrial segregation machinery for proper localization.