Insights into the functional mechanism of Erv1, an essential component of mitochondrial biogenesis

  • Xiaofan Tang

Student thesis: Phd


Mitochondria are important organelles that produce energy for cells and compass dedicated protein import systems since 99% proteins in mitochondria are imported from cytosol. Oxidative folding conjugated with disulfide-bond-formation trap is a unique protein import pathway in mitochondria intermembrane space. Erv1 serves as the disulfide bond generator in this pathway and belongs to the flavin-containing sulfhydryl oxidases. Erv1 functions to oxidise Mia40, the disulfide donor, and then pass electrons to molecular oxygen or cytochrome c. According to previous studies, enzymes belong to the ERV/ALR family, e.g. human ALR, Trypanosoma brucei Erv1, showed varied substrates catalytic efficiency towards molecular oxygen or cytochrome c. In thesis Chapter 3, the kinetics of oxidase and cytochrome c reductase of yeast Erv1 were investigated in detail, under aerobic and anaerobic conditions, using stopped-flow absorption spectroscopy and oxygen consumption analysis. Results show that Erv1 is a moderately active enzyme with the ability to use both O2 and cytochrome c as the electron acceptors, indicating that Erv1 contributes to mitochondrial hydrogen peroxide production. In thesis Chapter 4, liposomes that mimic the mitochondria inner membrane composition were used to investigate the presence of membrane on Erv1 activity. Liposomes change Erv1 from a cytochrome c preferable enzyme to no preference between O2 and cytochrome c enzyme. Considered the role of cardiolipin-cytochrome c binding in apoptosis, MIA (mitochondrial importing and assembly) pathway may play a role in cell death signalling to monitor the functionality of mitochondria. In thesis Chapter 5, to decipher the relation between the dipeptides and susbtrate catalytic efficiency in ERV/ALR enzymes, the active-site CXXC motif in Erv1 or ALR was swapped to compare the relation of CXXC motif with substrate activity. The dipeptide of the active-site CXXC motif alters Erv1/ALR enzymes from high activity “NW” (asparagine, tryptophan) to low activity “EE” (glutamic acid). From evolutionary perspective, the high activity of “NW” in Erv1 could be ascribed to not only diverse electron acceptors for Erv1 in the IMS, dioxygen, cytochrome c and Osm1/fumarate but the abundant H2O2 elimination enzymes. The “CEEC” in ALR seems to decrease the oxidase activity, thus to avoid the production of H2O2 in the mitochondria.
Date of Award1 Aug 2020
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorPing Xiao (Supervisor) & Hui Lu (Supervisor)


  • liposomes
  • cytochrome c
  • MIA pathway
  • disulfide bond
  • Erv1
  • CXXC motif

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