The Role of Hot13p and Redox Chemistry in the Mitochondrial TIM22 Import Pathway

Curran, Sean P.; Leuenberger, D.; Leverich, Edward P.; Hwang, David K.; Beverly, Kristen N.; Koehler, Carla M.

doi:10.1074/jbc.m404878200

Cited by 80 publications

(54 citation statements)

References 45 publications

(73 reference statements)

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“…Reduced Erv1 is oxidized by cytochrome c, which is then oxidized by electron transfer to either the cytochrome oxidase complex or to cytochrome c peroxidase (12,13). The disulfide transfer reaction mediated by Mia40 is promoted by another small protein in the IMS, Hot13 (9). Hot13 specifically interacts with Mia40 and presumably prevents Mia40 from binding to Zn 2ϩ ; thereby, facilitating its efficient oxidation by Erv1 (10).…”

Section: Structural Basis Of Yeast Tim40/mia40 As An Oxidative Translmentioning

confidence: 99%

“…The intermembrane space (IMS) between the outer and inner mitochondrial membranes contains many proteins with a molecular mass Ͻ20 kDa and characteristic cysteine motifs. Import of those small cysteine-containing proteins is driven by a redox-regulated translocator Tim40/Mia40 (4-6) and its partner proteins including Erv1 (7,8) and Hot13 (9,10).…”

Section: Structural Basis Of Yeast Tim40/mia40 As An Oxidative Translmentioning

confidence: 99%

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Structural basis of yeast Tim40/Mia40 as an oxidative translocator in the mitochondrial intermembrane space

Kawano

Yamano²,

Naoé³

et al. 2009

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

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The mitochondrial intermembrane space (IMS) contains many small cysteine-bearing proteins, and their passage across the outer membrane and subsequent folding require recognition and disulfide bond transfer by an oxidative translocator Tim40/Mia40 in the inner membrane facing the IMS. Here we determined the crystal structure of the core domain of yeast Mia40 (Mia40C4) as a fusion protein with maltose-binding protein at a resolution of 3 Å. The overall structure of Mia40C4 is a fruit-dish-like shape with a hydrophobic concave region, which accommodates a linker segment of the fusion protein in a helical conformation, likely mimicking a bound substrate. Replacement of the hydrophobic residues in this region resulted in growth defects and impaired assembly of a substrate protein. The Cys296-Cys298 disulfide bond is close to the hydrophobic concave region or possible substrate-binding site, so that it can mediate disulfide bond transfer to substrate proteins. These results are consistent with the growth phenotypes of Mia40 mutant cells containing Ser replacement of the conserved cysteine residues.

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Section: Structural Basis Of Yeast Tim40/mia40 As An Oxidative Translmentioning

confidence: 99%

Section: Structural Basis Of Yeast Tim40/mia40 As An Oxidative Translmentioning

confidence: 99%

Structural basis of yeast Tim40/Mia40 as an oxidative translocator in the mitochondrial intermembrane space

Kawano

Yamano²,

Naoé³

et al. 2009

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

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“…Reduced Mia40 is reoxidized by Erv1, which results in the activation of Mia40 for the next round of precursor binding and import Grumbt et al, 2007). Additional components contribute in the execution of the MIA pathway, including cytochrome c and cytochrome c peroxidase, which play a role in electron flow from Erv1, and the zinc-binding Hot13 that promotes the reoxidation of Mia40 by Erv1 (Curran et al, 2004;Bihlmaier et al, 2007;Dabir et al, 2007;Mesecke et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…On completion of disulfide exchange, precursor monomers are released in an oxidized state capable of assembly into mature complexes (Curran et al, 2002;Lu et al, 2004;Webb et al, 2006;Müller et al, 2008 Erv1, which results in the activation of Mia40 for the next round of precursor binding and import Grumbt et al, 2007). Additional components contribute in the execution of the MIA pathway, including cytochrome c and cytochrome c peroxidase, which play a role in electron flow from Erv1, and the zinc-binding Hot13 that promotes the reoxidation of Mia40 by Erv1 (Curran et al, 2004;Bihlmaier et al, 2007;Dabir et al, 2007;Mesecke et al, 2008). Mia40 is able to distinguish its own substrates from other cysteine-rich, but otherwise unrelated, proteins in the formation of disulfide-bonded intermediates (Milenkovic et al, 2007a).…”

Section: Introductionmentioning

confidence: 99%

Identification of the Signal Directing Tim9 and Tim10 into the Intermembrane Space of Mitochondria

Milenkovic

Ramming

Müller

et al. 2009

MBoC

148

140

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The intermembrane space of mitochondria contains the specific mitochondrial intermembrane space assembly (MIA) machinery that operates in the biogenesis pathway of precursor proteins destined to this compartment. The Mia40 component of the MIA pathway functions as a receptor and binds incoming precursors, forming an essential early intermediate in the biogenesis of intermembrane space proteins. The elements that are crucial for the association of the intermembrane space precursors with Mia40 have not been determined. In this study, we found that a region within the Tim9 and Tim10 precursors, consisting of only nine amino acid residues, functions as a signal for the engagement of substrate proteins with the Mia40 receptor. Furthermore, the signal contains sufficient information to facilitate the transfer of proteins across the outer membrane to the intermembrane space. Thus, here we have identified the mitochondrial intermembrane space sorting signal required for delivery of proteins to the mitochondrial intermembrane space. INTRODUCTIONMitochondria pose a great challenge for the proper delivery of proteins because of their complex architecture. Mitochondrial precursors must find their way to one of the four mitochondrial subcompartments: the outer membrane, intermembrane space, inner membrane, or matrix. As a direct consequence of this complexity, several machineries for the translocation and sorting of mitochondrial precursors have evolved. Interplay between these machineries and specific signals present in the precursors drive different protein targeting pathways (Schatz and Dobberstein, 1996;Emanuelsson and von Heijne, 2001;Jensen and Johnson, 2001;Endo et al., 2003;Koehler, 2004;Oka and Mihara, 2005;Dolezal et al., 2006;Neupert and Herrmann, 2007;Bolender et al., 2008). Initially, mitochondrial precursors are recognized in a signal-dependent manner by specific receptors and are transferred across the barrier of outer mitochondrial membrane by using the translocase of the outer membrane (TOM) complex. On the trans-side of the outer mitochondrial membrane, sorting machineries decode specific signals in precursors, and this results in the branching of protein import pathways. The most well characterized is the presequence pathway across the inner membrane driven by a cleavable and positively charged signal sequence, called a presequence, and the translocase of the inner membrane (TIM) 23 complex Endo et al., 2003;Oka and Mihara, 2005;Neupert and Herrmann, 2007;Bolender et al., 2008). The presequence is cleaved off by a specific protease liberating the mature protein. However, other mitochondrial signals are not proteolytically removed and remain as part of the native mitochondrial protein. One example is the recently identified ␤-signal that is recognized by the sorting and assembly machinery (SAM) complex to sort ␤-barrel proteins to the mitochondrial outer membrane . In other mitochondrial membrane proteins, the membrane domains, anchors, and their surrounding regions are used to some extent for selection of ...

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“…The IMS contains many small and soluble proteins, including small Tim proteins that lack presequences. These small IMS proteins reach the IMS through the TOM40 channel with the aid of the inner membrane proteins Tim40/Mia40 (8, 9) and Hot13 (10). Although some single-membrane spanning outer membrane proteins are directly inserted into the outer membrane from the TOM40 complex, ␤-barrel outer membrane proteins first reach the IMS side of the outer membrane through the TOM40 complex and are then inserted into the outer membrane with the assistance of small Tim proteins in the IMS and the TOB/ SAM complex in the outer membrane (11).…”

mentioning

confidence: 99%

The Phosphate Carrier Has an Ability to be Sorted to either the TIM22 Pathway or the TIM23 Pathway for Its Import into Yeast Mitochondria

Yamano

Ishikawa

Esaki

et al. 2005

Journal of Biological Chemistry

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Most mitochondrial proteins are synthesized in the cytosol, imported into mitochondria via the TOM40 (translocase of the mitochondrial outer membrane 40) complex, and follow several distinct sorting pathways to reach their destination submitochondrial compartments. Phosphate carrier (PiC) is an inner membrane protein with 6 transmembrane segments (TM1-TM6) and requires, after translocation across the outer membrane, the Tim9-Tim10 complex and the TIM22 complex to be inserted into the inner membrane. Here we analyzed an in vitro import of fusion proteins between various PiC segments and mouse dihydrofolate reductase. The fusion protein without TM1 and TM2 was translocated across the outer membrane but was not inserted into the inner membrane. The fusion proteins without TM1-TM4 were not inserted into the inner membrane but instead translocated across the inner membrane. Functional defects of Tim50 of the TIM23 complex caused either by depletion of the protein or the addition of anti-Tim50 antibodies blocked translocation of the fusion proteins without TM1-TM4 across the inner membrane, suggesting that lack of TM1-TM4 led to switch of its sorting pathway from the TIM22 pathway to the TIM23 pathway. PiC thus appears to have a latent signal for sorting to the TIM23 pathway, which is exposed by reduced interactions with the Tim9-Tim10 complex and maintenance of the import competence.Newly synthesized organellar and secretory proteins are translocated across or inserted into biological membranes before they become functional. Among several different eukaryotic organelles, mitochondria are unique in being bounded by two biological membranes, the outer and inner mitochondrial membranes, rendering delivery of mitochondrial proteins to their destination suborganellar compartments highly complex. Mitochondria have translocators, membrane protein complexes that recognize targeting/sorting signals of mitochondrial proteins and facilitate their translocation across and/or insertion into the membranes. The outer membrane contains two TOM 1 (translocase of the mitochondrial outer membrane) complexes as translocators, the TOM40 complex and TOB/SAM complex, and the inner membrane contains two TIM (translocase of the mitochondrial inner membrane) complexes as translocators, the TIM23 complex and TIM22 complex (1-3).The TOM40 complex mediates translocation across or insertion into the outer membrane for nearly all mitochondrial proteins. Most matrix proteins and some inner membrane proteins are synthesized in the cytosol as precursor proteins with an N-terminal cleavable presequence. After translocation through the TOM40 channel in the outer membrane, the proteins are passed onto the TIM23 complex and move through the TIM23 channel with the aid of MMC (mitochondrial Hsp70-associated motor and chaperone) proteins, i.e. mitochondrial Hsp70 and its partner proteins (4, 5). Polytopic inner membrane proteins, including metabolic carrier proteins, are synthesized in the cytosol without a presequence. After crossing the outer membrane via...

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The Role of Hot13p and Redox Chemistry in the Mitochondrial TIM22 Import Pathway

Cited by 80 publications

References 45 publications

Structural basis of yeast Tim40/Mia40 as an oxidative translocator in the mitochondrial intermembrane space

Structural basis of yeast Tim40/Mia40 as an oxidative translocator in the mitochondrial intermembrane space

Identification of the Signal Directing Tim9 and Tim10 into the Intermembrane Space of Mitochondria

The Phosphate Carrier Has an Ability to be Sorted to either the TIM22 Pathway or the TIM23 Pathway for Its Import into Yeast Mitochondria

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