Novel Mitochondrial Intermembrane Space Proteins as Substrates of the MIA Import Pathway

Gabriel, Kipros; Milenkovic, Dusanka; Chacińska, Agnieszka; Müller, Judith; Guiard, Bernard; Pfanner, Nikolaus; Meisinger, Chris

doi:10.1016/j.jmb.2006.10.038

Cited by 148 publications

(166 citation statements)

References 47 publications

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“…Considering that (i) the latter interaction is based on hydrophobic contacts established through an amphipathic α-helix of the substrate (23,27), and (ii) the residues close to CRAC motif show a tendency to form an α-helical amphipatic turn exposing hydrophobic residues to the solvent, we investigated the effect of these hydrophobic residues in complex formation with MIA40 through mutagenesis. MIA40/Mia40 interacts with ALR/Erv1 in two ways: (i) with unfolded and reduced Erv1 during its import (28,29), and (ii) with folded and oxidized ALR/Erv1 after its import to reoxidize the CPC motif of MIA40/ Mia40 (13,30). Our analysis focused so far exclusively on the second interaction; i.e., between folded/oxidized ALR and MIA40.…”

Section: Resultsmentioning

confidence: 99%

Molecular recognition and substrate mimicry drive the electron-transfer process between MIA40 and ALR

Banci

Bertini

Calderone

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

115

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Oxidative protein folding in the mitochondrial intermembrane space requires the transfer of a disulfide bond from MIA40 to the substrate. During this process MIA40 is reduced and regenerated to a functional state through the interaction with the flavin-dependent sulfhydryl oxidase ALR. Here we present the mechanistic basis of ALR-MIA40 interaction at atomic resolution by biochemical and structural analyses of the mitochondrial ALR isoform and its covalent mixed disulfide intermediate with MIA40. This ALR isoform contains a folded FAD-binding domain at the C-terminus and an unstructured, flexible N-terminal domain, weakly and transiently interacting one with the other. A specific region of the N-terminal domain guides the interaction with the MIA40 substrate binding cleft (mimicking the interaction of the substrate itself), without being involved in the import of ALR. The hydrophobicity-driven binding of this region ensures precise protein-protein recognition needed for an efficient electron transfer process.

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Section: Resultsmentioning

confidence: 99%

Molecular recognition and substrate mimicry drive the electron-transfer process between MIA40 and ALR

Banci

Bertini

Calderone

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

115

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“…As described in this study, the cysteine residues Cys-1 and Cys-2 are the ones that are in their thiol state in the reduced form of Mia40p in mitochondria. Moreover, Mia40p forms specific disulfide intermediates with substrates in the import reaction (8,15,16,39). It has been reported for the small Tim proteins, Tim9p and Tim10p, that the first cysteine residues, but not the others of the twin CX 3 C motif, are crucial for the formation of the mixed disulfide intermediate with Mia40p (40,41).…”

Section: Discussionmentioning

confidence: 98%

“…By a subsequent proteolytic step the mature protein is released into the IMS. On the other hand, there are many proteins of relatively small size that lack presequences but contain motifs of conserved cysteine residues, such as the twin CX 9 C motif in the copper chaperone Cox17p and in Cox19p, Mdm35p, Mic14p, and Mic17p or the twin CX 3 C motif in the family of small Tim proteins (6 -11).ProteinswithtwinCX n CmotifsusetheMia40p-dependent translocation pathway, which consists of at least two components in the IMS, Mia40p and Erv1p (8,(12)(13)(14)(15)(16)(17). Both proteins are essential for viability of yeast cells (12-14, 18 -20).…”

mentioning

confidence: 99%

Functional Characterization of Mia40p, the Central Component of the Disulfide Relay System of the Mitochondrial Intermembrane Space

Grumbt

Stroobant

Terziyska

et al. 2007

Journal of Biological Chemistry

116

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Mia40p and Erv1p are components of a translocation pathway for the import of cysteine-rich proteins into the intermembrane space of mitochondria. We have characterized the redox behavior of Mia40p and reconstituted the disulfide transfer system of Mia40p by using recombinant functional C-terminal fragment of Mia40p, Mia40C, and Erv1p. Oxidized Mia40p contains three intramolecular disulfide bonds. One disulfide bond connects the first two cysteine residues in the CPC motif. The second and the third bonds belong to the twin CX 9 C motif and bridge the cysteine residues of two CX 9 C segments. In contrast to the stabilizing disulfide bonds of the twin CX 9 C motif, the first disulfide bond was easily accessible to reducing agents. Partially reduced Mia40C generated by opening of this bond as well as fully reduced Mia40C were oxidized by Erv1p in vitro. In the course of this reaction, mixed disulfides of Mia40C and Erv1p were formed. Reoxidation of fully reduced Mia40C required the presence of the first two cysteine residues in Mia40C. However, efficient reoxidation of a Mia40C variant containing only the cysteine residues of the twin CX 9 C motif was observed when in addition to Erv1p low amounts of wild type Mia40C were present. In the reconstituted system the thiol oxidase Erv1p was sufficient to transfer disulfide bonds to Mia40C, which then could oxidize the variant of Mia40C. In summary, we reconstituted a disulfide relay system consisting of Mia40C and Erv1p.

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“…Most, but not all, substrates of Mia40, belong to the families of CX 9 C and CX 3 C proteins 3,11,16 . Similar to Mia40 itself, these proteins are composed of two short antiparallel helices that are covalently linked by two disulphide bonds.…”

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confidence: 99%

Mia40 targets cysteines in a hydrophobic environment to direct oxidative protein folding in the mitochondria

Koch

Schmid

2014

Nat Commun

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Mia40 catalyses the oxidative folding of disulphide-containing proteins in the mitochondria. The folding pathway is directed by the formation of the first mixed disulphide between Mia40 and its substrate. Here, we employ Cox17 to elucidate the molecular determinants of this reaction. Mia40 engages initially in a dynamic non-covalent enzyme-substrate complex that forms and dissociates within milliseconds. Cys36 of Cox17 forms the mixed disulphide in an extremely rapid reaction that is limited by the preceding complex formation with Mia40. Cys36 reacts much faster than the three other cysteines of Cox17, because it neighbours three hydrophobic residues. Mia40 binds preferentially to hydrophobic regions and the dynamic nature of the non-covalent complex allows rapid reorientation for an optimal positioning of the reactive cysteine. Mia40 thus uses the unique proximity between its substrate-binding site and the catalytic disulphide to select a particular cysteine for forming the critical initial mixed disulphide.

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Novel Mitochondrial Intermembrane Space Proteins as Substrates of the MIA Import Pathway

Cited by 148 publications

References 47 publications

Molecular recognition and substrate mimicry drive the electron-transfer process between MIA40 and ALR

Molecular recognition and substrate mimicry drive the electron-transfer process between MIA40 and ALR

Functional Characterization of Mia40p, the Central Component of the Disulfide Relay System of the Mitochondrial Intermembrane Space

Mia40 targets cysteines in a hydrophobic environment to direct oxidative protein folding in the mitochondria

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