A functionally divergent hydrogenosomal peptidase with protomitochondrial ancestry

SummaryMatrix proteins of mitochondria, hydrogenosomes and mitosomes are typically targeted and translocated into their respective organelles using N‐terminal presequences that are subsequently cleaved by a peptidase. Here we characterize a ∼47 kDa metallopeptidase, from the hydrogenosome‐bearing, unicellular eukaryote Trichomonas vaginalis, that contains the active site motif (HXXEHX76E) characteristic of the β subunit of the mitochondrial processing peptidase (MPP) and localizes to hydrogenosomes. The purified recombinant protein, named hydrogenosomal processing peptidase (HPP), is capable of cleaving a hydrogenosomal presequence in vitro, in contrast to MPP which requires both an α and β subunit for activity. T. vaginalis HPP forms an ∼100 kDa homodimer in vitro and also exists in an ∼100 kDa complex in vivo. Our phylogenetic analyses support a common origin for HPP and βMPP and demonstrate that gene duplication gave rise to αMPP and βMPP before the divergence of T. vaginalis and mitochondria‐bearing lineages. These data, together with published analyses of MPPs and putative mitosomal processing peptidases, lead us to propose that the length of targeting presequences and the subunit composition of organellar processing peptidases evolved in concert. Specifically, longer mitochondrial presequences may have evolved to require an α/β heterodimer for accurate cleavage, while shorter hydrogenosomal and mitosomal presequences did not.

A functionally divergent hydrogenosomal peptidase with protomitochondrial ancestry Journal Articles