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

Banci, Lucia; Bertini, Ivano; Calderone, V.; Cefaro, Chiara; Ciofi‐Baffoni, Simone; Gallo, Angelo; Kallergi, Emmanouela; Lionaki, Eirini; Pozidis, Charalambos; Tokatlidis, Kostas

doi:10.1073/pnas.1014542108

Cited by 95 publications

(140 citation statements)

References 37 publications

Supporting

Mentioning

121

Contrasting

Unclassified

Order By: Relevance

“…As with yeast Erv1 and ALR, mutation of the distal cysteine pair did not abolish the activity of TbERV1 with DTT, but in contrast to Erv1 orthologs from other organisms (30,37), as well as related sulfhydryl oxidases exhibiting a similar core FAD-binding domain Ero1 and Erv2 (38,39), the distal cysteine variant of TbERV1 was also active with TCEP as the substrate for sulfhydryl oxidation. In yeast Erv1, the distal cysteine pair is responsible for electron transfer from the substrate to the proximal cysteine pair and the distal cysteines interact directly with reduced Mia40 (40,41). Small substrates such as DTT, however, can access the active site directly.…”

Section: Resultsmentioning

confidence: 99%

“…Does this point toward the possibility that TbERV1 acts directly (i.e., without a Mia40-like partner) in the oxidative folding of small Tim proteins or other cysteine-rich proteins in trypanosome mitochondria (discussed further in references 6 and 8) and that our failure to see direct oxidative folding of recombinant TbTIM9 in vitro by TbERV1 is a consequence of technical limitations? Conceivably, the long, predicted disordered C-terminal domain separating the FAD-binding core helix bundle and distal cysteine pairs in TbERV1 (disorder predicted using the "Regional Order Neural Network" [54]) could guide the interaction with diverse cysteinerich substrates in much the same way the hydrophobic cleft of human Mia40 acts as a receptor for numerous substrates, including the flexible N-terminal domain of the human Erv1 ortholog ALR (40). Further work is needed to test this possibility.…”

Section: Figmentioning

confidence: 99%

See 1 more Smart Citation

Divergence of Erv1-Associated Mitochondrial Import and Export Pathways in Trypanosomes and Anaerobic Protists

et al. 2013

View full text Add to dashboard Cite

cIn yeast (Saccharomyces cerevisiae) and animals, the sulfhydryl oxidase Erv1 functions with Mia40 in the import and oxidative folding of numerous cysteine-rich proteins in the mitochondrial intermembrane space (IMS). Erv1 is also required for Fe-S cluster assembly in the cytosol, which uses at least one mitochondrially derived precursor. Here, we characterize an essential Erv1 orthologue from the protist Trypanosoma brucei (TbERV1), which naturally lacks a Mia40 homolog. We report kinetic parameters for physiologically relevant oxidants cytochrome c and O 2 , unexpectedly find O 2 and cytochrome c are reduced simultaneously, and demonstrate that efficient reduction of O 2 by TbERV1 is not dependent upon a simple O 2 channel defined by conserved histidine and tyrosine residues. Massive mitochondrial swelling following TbERV1 RNA interference (RNAi) provides evidence that trypanosome Erv1 functions in IMS protein import despite the natural absence of the key player in the yeast and animal import pathways, Mia40. This suggests significant evolutionary divergence from a recently established paradigm in mitochondrial cell biology. Phylogenomic profiling of genes also points to a conserved role for TbERV1 in cytosolic Fe-S cluster assembly. Conversely, loss of genes implicated in precursor delivery for cytosolic Fe-S assembly in Entamoeba, Trichomonas, and Giardia suggests fundamental differences in intracellular trafficking pathways for activated iron or sulfur species in anaerobic versus aerobic eukaryotes.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Divergence of Erv1-Associated Mitochondrial Import and Export Pathways in Trypanosomes and Anaerobic Protists

et al. 2013

View full text Add to dashboard Cite

show abstract

“…This suggests that the two cluster sites are functionally independent and that the M2 motif is not essential in the electron transfer process required for cytosolic Fe/S protein biogenesis. The M2 motif has been previously [9] found to modulate the subcellular localization of anamorsin in the IMS, being imported through the mitochondrial Mia40-dependent disulfide relay system [10,11,43,44]. In such a process, anamorsin is trapped in the IMS through the oxidoreductase Mia40, which specifically forms two disulfide bonds in the M2 motif.…”

Section: Reduced Fl Constructmentioning

confidence: 99%

Human anamorsin binds [2Fe–2S] clusters with unique electronic properties

et al. 2013

Self Cite

View full text Add to dashboard Cite

The eukaryotic anamorsin protein family, which has recently been proposed to be part of an electron transfer chain functioning in the early steps of cytosolic iron-sulfur (Fe/S) protein biogenesis, is characterized by a largely unstructured domain (CIAPIN1) containing two conserved cysteine-rich motifs (CX 8 CX 2 CXC and CX 2 CX 7 CX 2 C) whose Fe/S binding properties and electronic structures are not well defined. Here, we found that (1) each motif in human anamorsin is able to bind independently a [2Fe-2S] cluster through its four cysteine residues, the binding of one cluster mutually excluding the binding of the second, (2) the reduced [2Fe-2S] ? clusters exhibit a unique electronic structure with considerable anisotropy in their coordination environment, different from that observed in reduced, plant-type and vertebratetype [2Fe-2S] ferredoxin centers, (3) the reduced cluster bound to the CX 2 CX 7 CX 2 C motif reveals an unprecedented valence localization-to-delocalization transition as a function of temperature, and (4) only the [2Fe-2S] cluster bound to the CX 8 CX 2 CXC motif is involved in the electron transfer with its physiological protein partner Ndor1. The unique electronic properties of both [2Fe-2S] centers can be interpreted by considering that both cysteine-rich motifs are located in a highly unstructured and flexible protein region, whose local conformational heterogeneity can induce anisotropy in metal coordination. This study contributes to the understanding of the functional role of the CIAPIN1 domain in the anamorsin family, suggesting that only the [2Fe-2S] cluster bound to the CX 8 CX 2 CXC motif is indispensable in the electron transfer chain assembling cytosolic Fe/S proteins.

show abstract

“…Upon protein synthesis in the cytosol, the cysteine residues of IMS proteins remain in a reduced state, owing to the reducing properties of the cytosolic environment (11,12). After entering the TOM channel, precursor proteins are specifically recognized by Mia40 protein, and their cysteine residues are oxidized through the cooperative action of Mia40 and Erv1 proteins (7,(13)(14)(15)(16)(17). Mia40 is a receptor, folding catalyst, and disulfide carrier, and the Erv1 protein serves as a sulfhydryl oxidase.…”

mentioning

confidence: 99%

Retro-translocation of mitochondrial intermembrane space proteins

Brągoszewski

Wasilewski

Sakowska

et al. 2015

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

103

101

View full text Add to dashboard Cite

The content of mitochondrial proteome is maintained through two highly dynamic processes, the influx of newly synthesized proteins from the cytosol and the protein degradation. Mitochondrial proteins are targeted to the intermembrane space by the mitochondrial intermembrane space assembly pathway that couples their import and oxidative folding. The folding trap was proposed to be a driving mechanism for the mitochondrial accumulation of these proteins. Whether the reverse movement of unfolded proteins to the cytosol occurs across the intact outer membrane is unknown. We found that reduced, conformationally destabilized proteins are released from mitochondria in a size-limited manner. We identified the general import pore protein Tom40 as an escape gate. We propose that the mitochondrial proteome is not only regulated by the import and degradation of proteins but also by their retro-translocation to the external cytosolic location. Thus, protein release is a mechanism that contributes to the mitochondrial proteome surveillance. Because most mitochondrial proteins originate in the cytosol, mitochondria had to develop a protein import system. Given the complex architecture of these organelles, with two membranes and two aqueous compartments, protein import and sorting require the cooperation of several pathways. The main entry gate for precursor proteins is the translocase of the outer mitochondrial membrane (TOM) complex. Upon entering mitochondria, proteins are routed to different sorting machineries (1-5).Reaching the final location is one step in the maturation of mitochondrial proteins that must be accompanied by their proper folding. The mitochondrial intermembrane space assembly (MIA) pathway for intermembrane space (IMS) proteins illustrates the importance of coupling these processes because this pathway links protein import with oxidative folding (6-10). Upon protein synthesis in the cytosol, the cysteine residues of IMS proteins remain in a reduced state, owing to the reducing properties of the cytosolic environment (11,12). After entering the TOM channel, precursor proteins are specifically recognized by Mia40 protein, and their cysteine residues are oxidized through the cooperative action of Mia40 and Erv1 proteins (7,(13)(14)(15)(16)(17). Mia40 is a receptor, folding catalyst, and disulfide carrier, and the Erv1 protein serves as a sulfhydryl oxidase. The oxidative folding is believed to provide a trapping mechanism that prevents the escape of proteins from the IMS back to the cytosol (10, 13, 18). Our initial result raised a possibility that the reverse process can also occur, as we observed the relocation of in vitro imported Tim8 from mitochondria to the incubation buffer (13). Thus, we sought to establish whether and how this process can proceed in the presence of the intact outer membrane (OM). Our study provides, to our knowledge, the first characterization of the mitochondrial protein retro-translocation. The protein retro-translocation serves as a regulatory and quality control mechanism for th...

show abstract

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

Cited by 95 publications

References 37 publications

Divergence of Erv1-Associated Mitochondrial Import and Export Pathways in Trypanosomes and Anaerobic Protists

Divergence of Erv1-Associated Mitochondrial Import and Export Pathways in Trypanosomes and Anaerobic Protists

Human anamorsin binds [2Fe–2S] clusters with unique electronic properties

Retro-translocation of mitochondrial intermembrane space proteins

Contact Info

Product

Resources

About