Abstract
Some organisms, like Trichomonas vaginalis, contain mitochondria-related hydrogen-producing organelles, called hydrogenosomes. The protein targeting into these organelles is proposed to be similar to the well-studied mitochondria import. Indeed, S. cerevisiae mitochondria and T. vaginalis hydrogenosomes share some components of protein import complexes. However, it is still unknown whether targeting signals directing substrate proteins to hydrogenosomes can support in other eukaryotes specific mitochondrial localization. To address this issue, we investigated the intracellular localization of three hydrogenosomal tail-anchored proteins expressed in yeast cells. We observed that these proteins were targeted to both mitochondria and ER with a variable dependency on the mitochondrial MIM complex. Our results suggest that the targeting signal of TA proteins are only partially conserved between hydrogenosomes and yeast mitochondria.
Highlights
Mitochondria are essential organelles that evolved from the endosymbiosis of α-proteobacteria and ancestral archaea cells [1]
To study the conservation of the targeting of TA proteins between T. vaginalis and S. cerevisiae, we expressed in yeast cells out of the five newly identified hydrogenosomal proteins the three proteins that have less hydrophobic transmembrane segment (TMS), a typical characteristic of mitochondrial TA proteins, and investigated their localization and topology
To confirm the successful separation of the cellular compartments, the mitochondrial TA protein Fis1, the Hydrogenosomal tail-anchored proteins in yeast cells protein. (E) Microsomes isolated from WT cells were treated with proteinase K (PK) in the presence or absence of TritonX-100 (TX) and analysed by Western blot and immunodecoration with the indicated antibodies. (F) Microsomes isolated from cells expressing 3HA-TA4 were treated with the enzymes Endoglycosidase H (EndoH) or Peptide:N-Glycosidase F (PNGase) and analysed by Western blot and immunodecoration
Summary
Mitochondria are essential organelles that evolved from the endosymbiosis of α-proteobacteria and ancestral archaea cells [1]. Some key components of the mitochondria import machineries, such as subunits of the translocases of the outer and inner membranes (TOM and TIM complexes, respectively), are conserved between S. cerevisiae and T. vaginalis, the two organisms belong to evolutionary very distant supergroups (Opistokonta and Excavata, respectively) [6, 7]. This observation underlies the relation in the evolution of both organelles [2, 7]. It is not clear whether the protein targeting signals are conserved between mitochondria and hydrogenosomes
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