Architecture of the Yeast Mitochondrial Iron-Sulfur Cluster Assembly Machinery

Ranatunga, Wasantha; Gakh, Oleksandr; Galeano, Belinda K.; Smith, Douglas Y.; Söderberg, Christopher; Al-Karadaghi, Salam; Thompson, James R.; Isaya, Grazia

doi:10.1074/jbc.m115.712414

Cited by 18 publications

(34 citation statements)

References 65 publications

(145 reference statements)

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“…We found that overexpression of YFH1 results in increased Yfh1 in mitochondria, yet it only showed mild suppression of the sterol intermediate accumulation seen in ⌬erg29 cells. It may be that oxidized Yfh1 is functionally inactive or that Yfh1 suppresses the ⌬erg29 phenotype by chelating iron, as Yfh1 has been suggested to be an iron-binding protein (8,11,50). The function of Pet20 is unclear except that its loss renders respiratory active yeast susceptible to a wide variety of conditions, including H 2 O 2 and the antifungal drug fluconazole (15).…”

Section: Increased Sterol Intermediates Affect Fe-s Cluster Synthesismentioning

confidence: 99%

“…Many of the genes involved in Fe-S cluster synthesis and particularly in the mitochondrial synthesis and export of Fe-S clusters are highly conserved in all eukaryotes. Yfh1, the yeast equivalent of mammalian frataxin, plays an important role in the early steps of Fe-S cluster synthesis (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Whereas the exact role has not been defined, loss of Yfh1 results in severely compromised Fe-S cluster synthesis and decreased mitochondrial function.…”

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confidence: 99%

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Altered sterol metabolism in budding yeast affects mitochondrial iron–sulfur (Fe-S) cluster synthesis

Chen

Kaplan

et al. 2018

Journal of Biological Chemistry

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Ergosterol synthesis is essential for cellular growth and viability of the budding yeast , and intracellular sterol distribution and homeostasis are therefore highly regulated in this species. Erg25 is an iron-containing C4-methyl sterol oxidase that contributes to the conversion of 4,4-dimethylzymosterol to zymosterol, a precursor of ergosterol. The gene encodes an endoplasmic reticulum (ER)-associated protein, and here we identified a role for Erg29 in the methyl sterol oxidase step of ergosterol synthesis. deletion resulted in lethality in respiring cells, but respiration-incompetent (Rho or Rho) cells survived, suggesting that Erg29 loss leads to accumulation of oxidized sterol metabolites that affect cell viability. Down-regulation of expression in Δ cells indeed led to accumulation of methyl sterol metabolites, resulting in increased mitochondrial oxidants and a decreased ability of mitochondria to synthesize iron-sulfur (Fe-S) clusters due to reduced levels of Yfh1, the mammalian frataxin homolog, which is involved in mitochondrial iron metabolism. Using a high-copy genomic library, we identified suppressor genes that permitted growth of Δ cells on respiratory substrates, and these included genes encoding the mitochondrial proteins Yfh1, Mmt1, Mmt2, and Pet20, which reversed all phenotypes associated with loss of Of note, loss of Erg25 also resulted in accumulation of methyl sterol metabolites and also increased mitochondrial oxidants and degradation of Yfh1. We propose that accumulation of toxic intermediates of the methyl sterol oxidase reaction increases mitochondrial oxidants, which affect Yfh1 protein stability. These results indicate an interaction between sterols generated by ER proteins and mitochondrial iron metabolism.

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Section: Increased Sterol Intermediates Affect Fe-s Cluster Synthesismentioning

confidence: 99%

mentioning

confidence: 99%

Altered sterol metabolism in budding yeast affects mitochondrial iron–sulfur (Fe-S) cluster synthesis

Chen

Kaplan

et al. 2018

Journal of Biological Chemistry

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“…Frataxin, which was shown to interact with the preformed ternary complex 55 , was proposed to bind in a ratio of 1:2:1:1 in the quaternary complex (NFS1:ISD11:ISCU:FXN) 54 . The source of iron for the nascent cluster remains to be identified, but proposed donors include frataxin 56, 57 , which has acidic surface patches to which iron binds with low affinity, or a complex of glutathione and glutaredoxin 58 . Electrons, needed to achieve the final electronic configurations of Fe-S clusters, are provided by ferredoxins (FDX1/2) and ferredoxin reductase (FDXR) 59, 60 .…”

Section: Fe-s Cluster Biogenesis: the Assembly Stepmentioning

confidence: 99%

“…An array of techniques and methods has been developed to enable researchers to obtain intact and biologically active Fe–S proteins in pure and stable forms. In addition, methods for the generation of highly concentrated samples containing Fe-S clusters isotopically labelled with 57 Fe for Mössbauer and related spectroscopies have enabled researchers to identify novel mammalian Fe-S proteins, and to uncover new biological functions for Fe-S clusters in cellular metabolism 26 .…”

Section: Introductionmentioning

confidence: 99%

Mammalian Fe–S proteins: definition of a consensus motif recognized by the co-chaperone HSC20

Maio

Rouault

2016

Metallomics

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Iron-sulfur (Fe-S) clusters are inorganic cofactors that are fundamental to several biological processes in all three kingdoms of life. In most organisms, Fe-S clusters are initially assembled on a scaffold protein, ISCU, and subsequently transferred to target proteins or to intermediate carriers by a dedicated chaperone/co-chaperone system. The delivery of assembled Fe-S clusters to recipient proteins is a crucial step in the biogenesis of Fe-S proteins, and, in mammals, it relies on the activity of a multiprotein transfer complex that contains the chaperone HSPA9, the co-chaperone HSC20 and the scaffold ISCU. How the transfer complex efficiently engages recipient Fe-S target proteins involves specific protein interactions that are not fully understood. This mini review focuses on recent insights into the molecular mechanism of amino acid motif recognition and discrimination by the co-chaperone HSC20, which guides Fe-S cluster delivery.

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“… 24 The availability of the iron-free and functional Yfh1 Y73A and FXN 42–210 oligomers has recently enabled structural studies to characterize iron-independent protein–protein interactions involved in the yeast and human Fe–S cluster assembly machineries. 16 , 17 These macromolecular complexes share architectures suitable to ensure the concerted and protected transfer of potentially toxic iron and sulfur atoms to the scaffold during Fe–S cluster assembly. 16 , 17 …”

Section: Introductionmentioning

confidence: 99%

Zinc and the iron donor frataxin regulate oligomerization of the scaffold protein to form new Fe–S cluster assembly centers

et al. 2017

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Early studies of the bacterial Fe-S cluster assembly system provided have structural details for how the scaffold protein and the cysteine desulfurase interact. This study and an additional study on the yeast and human systems elucidated a conserved mechanism for sulfur donation, but did not provide any conclusive insights into the mechanism for iron delivery from the iron donor frataxin to the scaffold. We previously showed that oligomerization is a mechanism by which yeast frataxin (Yfh1) can promote assembly of the core machinery for Fe-S cluster synthesis both in vitro and in cells, such that the scaffold protein Isu1 can bind to Yfh1 independent of the presence of the cysteine desulfurase Nfs1. Herein, in the absence of Yfh1, Isu1 was found to exist in two forms: one mostly monomeric with limited tendency to dimerize and other with a strong propensity to oligomerize. The monomeric form is stabilized by zinc, and the loss of zinc promotes formation of a dimer and higher order oligomers; however, upon binding to oligomeric Yfh1, both forms take on a similar symmetrical trimeric configuration that places the Fe-S cluster coordinating residues of Isu1 in close proximity to iron-binding residues of Yfh1. This configuration is suitable for the docking of Nfs1 in a manner that provides a structural context for coordinate iron and sulfur donation to the scaffold. Moreover, distinct structural features suggest that under physiological conditions, the zinc-regulated abundance of monomeric vs. oligomeric Isu1 yields [Yfh1]•[Isu1] complexes with different Isu1 configurations that afford unique functional properties for Fe-S cluster assembly and delivery.

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Architecture of the Yeast Mitochondrial Iron-Sulfur Cluster Assembly Machinery

Cited by 18 publications

References 65 publications

Altered sterol metabolism in budding yeast affects mitochondrial iron–sulfur (Fe-S) cluster synthesis

Altered sterol metabolism in budding yeast affects mitochondrial iron–sulfur (Fe-S) cluster synthesis

Mammalian Fe–S proteins: definition of a consensus motif recognized by the co-chaperone HSC20

Zinc and the iron donor frataxin regulate oligomerization of the scaffold protein to form new Fe–S cluster assembly centers

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