Intramolecular Disulfide Bond of Tim22 Protein Maintains Integrity of the TIM22 Complex in the Mitochondrial Inner Membrane

Okamoto, Hiroaki; Miyagawa, Akiko; Shiota, Takuya; Tamura, Yasushi; Endo, Toshiya

doi:10.1074/jbc.m113.543264

Cited by 28 publications

(39 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the targeting signal for ScTim22 has not been well characterized, it has been shown that this protein requires the Tom20 receptor, and after translocation through the Tom40 channel, it is also inserted into the mitochondrial inner membrane via the TIM22 complex (47,48). Recent reports show that the import and assembly of Tim22 in fungi depend on Tim18, a component of the TIM22 translocase, as well as Mia40, an IMS protein (48,49). Oxidation of a pair of intramolecular sulfhydryl groups in Tim22 is critical for the import and assembly of this protein into the mitochondrial inner membrane (48,49).…”

Section: Discussionmentioning

confidence: 99%

“…Recent reports show that the import and assembly of Tim22 in fungi depend on Tim18, a component of the TIM22 translocase, as well as Mia40, an IMS protein (48,49). Oxidation of a pair of intramolecular sulfhydryl groups in Tim22 is critical for the import and assembly of this protein into the mitochondrial inner membrane (48,49). Trypanosomatids do not have a homolog of either Tim18 or Mia40, which could potentially explain why ScTim22 was unable to assemble into the T. brucei mitochondrial inner membrane.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Functional Complementation Analyses Reveal that the Single PRAT Family Protein of Trypanosoma brucei Is a Divergent Homolog of Tim17 in Saccharomyces cerevisiae

et al. 2015

View full text Add to dashboard Cite

bTrypanosoma brucei, a parasitic protozoan that causes African trypanosomiasis, possesses a single member of the presequence and amino acid transporter (PRAT) protein family, which is referred to as TbTim17. In contrast, three homologous proteins, ScTim23, ScTim17, and ScTim22, are found in Saccharomyces cerevisiae and higher eukaryotes. Here, we show that TbTim17 cannot rescue Tim17, Tim23, or Tim22 mutants of S. cerevisiae. We expressed S. cerevisiae Tim23, Tim17, and Tim22 in T. brucei. These heterologous proteins were properly imported into mitochondria in the parasite. Further analysis revealed that although ScTim23 and ScTim17 were integrated into the mitochondrial inner membrane and assembled into a protein complex similar in size to TbTim17, only ScTim17 was stably associated with TbTim17. In contrast, ScTim22 existed as a protease-sensitive soluble protein in the T. brucei mitochondrion. In addition, the growth defect caused by TbTim17 knockdown in T. brucei was partially restored by the expression of ScTim17 but not by the expression of either ScTim23 or ScTim22, whereas the expression of TbTim17 fully complemented the growth defect caused by TbTim17 knockdown, as anticipated. Similar to the findings for cell growth, the defect in the import of mitochondrial proteins due to depletion of TbTim17 was in part restored by the expression of ScTim17 but was not complemented by the expression of either ScTim23 or ScTim22. Together, these results suggest that TbTim17 is divergent compared to ScTim23 but that its function is closer to that of ScTim17. In addition, ScTim22 could not be sorted properly in the T. brucei mitochondrion and thus failed to complement the function of TbTim17.A majority of proteins in the mitochondria are encoded by nuclear DNA. These proteins are imported by the translocase of the mitochondrial outer membrane (TOM) and the translocase of the mitochondrial inner membrane (TIM) (1, 2). The TOMs and TIMs are multiprotein complexes whose structure and function have been extensively characterized in fungi and recently in humans and plants. The TOM complex serves as the entry gate for virtually all mitochondrial proteins (3). There are two TIM complexes, TIM23 and TIM22, in the majority of eukaryotes analyzed so far. Unlike TOM, the TIM complexes have substrate specificities. The TIM23 complex imports proteins that contain an N-terminal targeting signal (MTS) into the mitochondrial matrix and, if they contain an additional sorting signal, into the inner membrane (4, 5). Tim23 and Tim17, together with the receptor Tim50, form the core of the TIM23 complex. This core complex seems to be sufficient for transport of proteins into the mitochondrial inner membrane by a stop-transfer pathway. For translocation of proteins to the mitochondrial matrix, the ATP-dependent action of the import motor of the TIM23 complex is additionally required (4-6). The TIM22 complex, on the other hand, is involved in the translocation and insertion of a special class of mitochondrial inner membrane proteins. These pr...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Functional Complementation Analyses Reveal that the Single PRAT Family Protein of Trypanosoma brucei Is a Divergent Homolog of Tim17 in Saccharomyces cerevisiae

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Tim22 from Saccharomyces cerevisiae yeast was shown to form an intramolecular disulfide bond1617. Thus, we sought to determine the redox state of Tim17.…”

Section: Resultsmentioning

confidence: 99%

“…The dependence of Tim22 on Mia40 was questioned17. To assess the involvement of Mia40 in the import of C. albicans Tim22, we isolated mitochondria from both S. cerevisiae and C. albicans and first incubated them with Tim9, the classic MIA pathway substrate (Fig.…”

Section: Resultsmentioning

confidence: 99%

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

Wróbel

Sokòl

Chojnacka

et al. 2016

Sci Rep

View full text Add to dashboard Cite

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.

show abstract

“…5) [174,175]. Mia40-mediated oxidation of the Tim22 pre-303cursor is a prerequisite for the subsequent assembly into the TIM22 304 complex[175,176]. Mia40 also confers disulfide bonds to precursor pro-305 teins, which are further imported into the matrix(Fig.…”

mentioning

confidence: 99%

Cooperation of protein machineries in mitochondrial protein sorting

Wenz

Opaliński

Wiedemann

et al. 2015

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

View full text Add to dashboard Cite

The function of mitochondria depends on the import of proteins, which are synthesized as precursors on cytosolic ribosomes. The majority of the precursor proteins are sorted into the mitochondrial subcompartments via five distinct routes. Recent studies revealed that molecular cooperation between protein machineries is a central feature of mitochondrial protein biogenesis. First, coupling to various partner proteins affects the substrate specificity of translocases and single translocation steps. Second, there is a substantial cooperation between different protein translocases in the import of specific precursor proteins. Third, protein transport is intimately linked to processing, folding and assembly reactions. Fourth, sorting of precursor proteins is functionally and physically connected to protein machineries, which fulfill central functions for respiration, maintenance of membrane architecture and form contacts to the endoplasmic reticulum. Therefore, we propose that the protein transport systems are part of a complicated protein network for mitochondrial biogenesis.

show abstract

Intramolecular Disulfide Bond of Tim22 Protein Maintains Integrity of the TIM22 Complex in the Mitochondrial Inner Membrane

Cited by 28 publications

References 37 publications

Functional Complementation Analyses Reveal that the Single PRAT Family Protein of Trypanosoma brucei Is a Divergent Homolog of Tim17 in Saccharomyces cerevisiae

Functional Complementation Analyses Reveal that the Single PRAT Family Protein of Trypanosoma brucei Is a Divergent Homolog of Tim17 in Saccharomyces cerevisiae

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

Cooperation of protein machineries in mitochondrial protein sorting

Contact Info

Product

Resources

About