An interaction between frataxin and Isu1/Nfs1 that is crucial for Fe/S cluster synthesis on Isu1

Gerber, Jana; Mühlenhoff, Ulrich; Lill, Roland

doi:10.1038/sj.embor.embor918

Cited by 312 publications

(299 citation statements)

References 29 publications

(48 reference statements)

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“…Are Important in Vivo-Although it has been previously shown that the Isu scaffold protein and Ssq1 can physically interact (7,35), the present study provides the first evidence that a direct interaction between the Fe-S cluster scaffold protein Isu and the molecular chaperone Ssq1 is critical in vivo. The three Cterminal residues of the LPPVK peptide of Isu are responsible for its functional interaction with Ssq1 because several amino acid substitutions in this motif inhibited both formation of the Isu-Ssq1 complex and the ability of Isu to stimulate Ssq1 ATPase activity.…”

Section: Direct Interactions Between Isu and Ssq1mentioning

confidence: 80%

Sequence-specific Interaction between Mitochondrial Fe-S Scaffold Protein Isu and Hsp70 Ssq1 Is Essential for Their in Vivo Function

Dutkiewicz

Schilke

Cheng

et al. 2004

Journal of Biological Chemistry

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Isu, the scaffold for assembly of Fe-S clusters in the yeast mitochondrial matrix, is a substrate protein for the Hsp70 Ssq1 and the J-protein Jac1 in vitro. As expected for an Hsp70-substrate interaction, the formation of a stable complex between Isu and Ssq1 requires Jac1 in the presence of ATP. Here we report that a conserved tripeptide, PVK, of Isu is critical for interaction with Ssq1 because amino acid substitutions in this tripeptide inhibit both the formation of the Isu-Ssq1 complex and the ability of Isu to stimulate the ATPase activity of Ssq1. These biochemical defects correlate well with the growth defects of cells expressing mutant Isu proteins. We conclude that the Ssq1-Isu substrate interaction is critical for Fe-S cluster biogenesis in vivo. The ability of Jac1 and mutant Isu proteins to cooperatively stimulate the ATPase activity of Ssq1 was also measured. Increasing the concentration of Jac1 and mutant Isu together but not individually partially overcame the effect of the reduced affinity of the Isu mutant proteins for Ssq1. These results, along with the observation that overexpression of Jac1 was able to suppress the growth defect of an ISU mutant, support the hypothesis that Isu is "targeted" to Ssq1 by Jac1, with a preformed Jac1-Isu complex interacting with Ssq1.

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Section: Direct Interactions Between Isu and Ssq1mentioning

confidence: 80%

Sequence-specific Interaction between Mitochondrial Fe-S Scaffold Protein Isu and Hsp70 Ssq1 Is Essential for Their in Vivo Function

Dutkiewicz

Schilke

Cheng

et al. 2004

Journal of Biological Chemistry

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“…Yfh1, the yeast frataxin homolog, has been proposed to serve as an iron donor and/or a regulator of Nfs1 function (9-11). Isu, Nfs1, and Yfh1 can bind with one another to form a so-called "Fe-S cluster assembly" complex (11)(12)(13). Transfer of the assembled clusters to recipient proteins requires a specialized Hsp70 chaperone system composed of the Hsp70 Ssq1 and the J-protein cochaperone Jac1, as well as the nucleotide release factor Mge1 (14,15).…”

mentioning

confidence: 99%

Cysteine desulfurase Nfs1 and Pim1 protease control levels of Isu, the Fe-S cluster biogenesis scaffold

Song

Marszałek

Craig

2012

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

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Fe-S clusters are critical prosthetic groups for proteins involved in various critical biological processes. Before being transferred to recipient apo-proteins, Fe-S clusters are assembled on the highly conserved scaffold protein Isu, the abundance of which is regulated posttranslationally on disruption of the cluster biogenesis system. Here we report that Isu is degraded by the Lon-type AAA+ ATPase protease of the mitochondrial matrix, Pim1. Nfs1, the cysteine desulfurase responsible for providing sulfur for cluster formation, is required for the increased Isu stability occurring after disruption of cluster formation on or transfer from Isu. Physical interaction between the Isu and Nfs1 proteins, not the enzymatic activity of Nfs1, is the important factor in increased stability. Analysis of several conditions revealed that high Isu levels can be advantageous or disadvantageous, depending on the physiological condition. During the stationary phase, elevated Isu levels were advantageous, resulting in prolonged chronological lifespan. On the other hand, under iron-limiting conditions, high Isu levels were deleterious. Compared with cells expressing normal levels of Isu, such cells grew poorly and exhibited reduced activity of the heme-containing enzyme ferric reductase. Our results suggest that modulation of the degradation of Isu by the Pim1 protease is a regulatory mechanism serving to rapidly help balance the cell's need for critical ironrequiring processes under changing environmental conditions. proteolysis | Hsp70 | aging | Saccharomyces cerevisiae

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“…The ISC machinery comprises ISCU, a scaffold protein on which Fe-S clusters are assembled, NFS1, a pyridoxal phosphatedependent cysteine desulfurase, ISD11 and FXN [20][21][22][23] . The eukaryotic ISC machinery has evolved from bacteria and thus some of the primary steps of Fe-S cluster assembly have been conserved 16,24,25 .…”

mentioning

confidence: 99%

Mammalian frataxin directly enhances sulfur transfer of NFS1 persulfide to both ISCU and free thiols

et al. 2015

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Friedreich's ataxia is a severe neurodegenerative disease caused by the decreased expression of frataxin, a mitochondrial protein that stimulates iron-sulfur (Fe-S) cluster biogenesis. In mammals, the primary steps of Fe-S cluster assembly are performed by the NFS1-ISD11-ISCU complex via the formation of a persulfide intermediate on NFS1. Here we show that frataxin modulates the reactivity of NFS1 persulfide with thiols. We use maleimide-peptide compounds along with mass spectrometry to probe cysteine-persulfide in NFS1 and ISCU. Our data reveal that in the presence of ISCU, frataxin enhances the rate of two similar reactions on NFS1 persulfide: sulfur transfer to ISCU leading to the accumulation of a persulfide on the cysteine C104 of ISCU, and sulfur transfer to small thiols such as DTT, L-cysteine and GSH leading to persulfuration of these thiols and ultimately sulfide release. These data raise important questions on the physiological mechanism of Fe-S cluster assembly and point to a unique function of frataxin as an enhancer of sulfur transfer within the NFS1-ISD11-ISCU complex.

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An interaction between frataxin and Isu1/Nfs1 that is crucial for Fe/S cluster synthesis on Isu1

Abstract: EMBO reports 4, 906-911 (2003)

Cited by 312 publications

References 29 publications

Sequence-specific Interaction between Mitochondrial Fe-S Scaffold Protein Isu and Hsp70 Ssq1 Is Essential for Their in Vivo Function

Sequence-specific Interaction between Mitochondrial Fe-S Scaffold Protein Isu and Hsp70 Ssq1 Is Essential for Their in Vivo Function

Cysteine desulfurase Nfs1 and Pim1 protease control levels of Isu, the Fe-S cluster biogenesis scaffold

Mammalian frataxin directly enhances sulfur transfer of NFS1 persulfide to both ISCU and free thiols

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