The presence of disulfide bonds reveals an evolutionarily conserved mechanism involved in mitochondrial protein translocase assembly.

Lidia Wrobel,Magdalena Chojnacka,Anna M Sokol,Agnieszka Chacinska

doi:10.1038/srep27484

Abstract

Disulfide bond formation is crucial for the biogenesis and structure of many proteins that are localized in the intermembrane space of mitochondria. The importance of disulfide bond formation within mitochondrial proteins was extended beyond soluble intermembrane space proteins. Tim22, a membrane protein and core component of the mitochondrial translocase TIM22, forms an intramolecular disulfide bond in yeast. Tim22 belongs to the Tim17/Tim22/Tim23 family of protein translocases. Here, we present evidence of the high evolutionary conservation of disulfide bond formation in Tim17 and Tim22 among fungi and metazoa. Topological models are proposed that include the location of disulfide bonds relative to the predicted transmembrane regions. Yeast and human Tim22 variants that are not oxidized do not properly integrate into the membrane complex. Moreover, the lack of Tim17 oxidation disrupts the TIM23 translocase complex. This underlines the importance of disulfide bond formation for mature translocase assembly through membrane stabilization of weak transmembrane domains.

Highlights

Of mitochondrial Ca2+ uniporter function in human cells[13]
We demonstrated a conserved pattern of cysteine residues in Tim[17] and Tim[22] but not Tim[23]
Our analysis revealed the formation of disulfide bonds in Tim[17] and Tim[22] proteins in S. cerevisiae, C. albicans, and H. sapiens

Summary

Introduction

Of mitochondrial Ca2+ uniporter function in human cells[13]. The formation of the disulfide bond can be part of a protein quality control system. These results demonstrate that S. cerevisiae Tim[17] is a partially oxidized protein that likely has one disulfide bond and two cysteine residues with free thiol groups. Mitochondria that were isolated from tim[] and wildtype cells were pretreated with TCEP to reduce existing disulfide bonds (Fig. 1d, lanes 2, 4).

Results

Conclusion