The kinetoplastid-specific transcription factor mtTF1 is essential for mitochondrial gene expression and maxicircle replication in Trypanosoma brucei

Mitochondrial DNA replication and gene expression are essential for cell survival. In Trypanosoma brucei, a protozoan animal and human parasite, the mitochondrial RNA polymerase (mtRNAP, Tb927.11.5780) plays roles in both transcription and DNA replication. This study identifies and characterizes the first mitochondrial transcription factor (mtTF1, Tb927.6.4510) in the Kinetoplastea. The mtRNAP and mtTF1 form a high-molecular-weight complex that localizes to the kinetoplast DNA (kDNA) and is essential for parasite survival in both life cycle stages. Their localization is interdependent, and both proteins influence maxicircle replication, but not minicircle replication. Knockdown of either protein results in altered gene expression, particularly affecting the minor strand of the mitochondrial genome. mTF1 specifically binds to kDNA and since it is unique to the Kinetoplastea, it might prove to be a promising drug target.