The Diverged Trypanosome MICOS Complex as a Hub for Mitochondrial Cristae Shaping and Protein Import

Abstract

This work deals with MICOS, which stands for mitochondrial contact site and cristae organization system. Until now this multiprotein complex has been analyzed experimentally only in yeast and mammals, who belong to the supergroup Opisthokonta. Our study was done on the parasitic protist T. brucei, a member of the another supergroup called Excavata, which is very diverged from opisthokonts.Thus, it is the very first study done outside of Opisthokonta. This could be very useful in the future for a comparative analysis approach. Our results show that the MICOS complex in T. brucei is composed of 9 subunits, most of which are essential for normal growth. It is required for the maintenance of discoidal cristae that typify excavates such as kinetoplastids and euglenids and mediating the mitochondrial outer and inner membranes contacts. In addition, we discovered that the mitochondrial contact site and cristae organization system may participate in the intermembrane space protein import and help in the oxydative phosphorylation complex formation. It seems that this interesting complex is involved in even more cellular processes.