Lineage-specific innovations expand mitochondrial proteomes in kinetoplastids.

Trypanosoma brucei and Leishmania tarentolae are model kinetoplastids whose mitochondria contain a unique DNA network, kinetoplast DNA (kDNA), and exhibit specialized features, including developmental remodeling and RNA editing. By integrating mass spectrometry-based protein correlation profiling with published datasets, we assembled inventories of 1,666 mitochondrial proteins in T. brucei and 1,594 in L. tarentolae. These include 124 polypeptides not previously recognized as mitochondrial. Despite their phylogenetic distance, trypanosomes and leishmanias maintain highly conserved mitoproteomes, including about 700 components with no detectable homologs in other eukaryotes. Comparison of T. brucei insect and mammalian stages revealed similar mitoproteome compositions but globally reduced mitochondrial protein abundance in the latter, except for components of calcium homeostasis and the alternative oxidase pathway. We also detected ten kDNA-encoded proteins, including products of pan-edited transcripts. These inventories establish a framework for functional analysis of previously uncharacterized mitochondrial factors and illuminate innovations that have shaped kinetoplastid evolution.