Native mass spectrometric studies of IscSU reveal a concerted, sulfur-initiated mechanism of iron–sulfur cluster assembly

Bennett, Sophie P; Crack, Jason C.; Puglisi, Rita; Pastore, Annalisa; Brun, Nick E. Le

doi:10.1039/d2sc04169c

Cited by 15 publications

(8 citation statements)

References 90 publications

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“…Importantly, iron, but not zinc binding allowed FeS formation by an in vitro ISC assembly complex 53 . ZnCPT quantified both ISCU Cys95 and Cys138 as dynamic zinc binding residues, while NFS1 Cys381 did not appear to bind zinc, supporting a Frataxin-bound intermediary state, awaiting initation of catalysis ( Figure 5E ) 43,44,55 . These data provide physiological evidence of dynamic zinc-dependent regulation of ISC assembly in human cells, which possibly also extends to the wider family of ISC binding proteins 56 .…”

Section: Resultsmentioning

confidence: 91%

A comprehensive landscape of the zinc-regulated human proteome

Burger,

Mittenbühler,

Xiao

et al. 2024

Preprint

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Zinc is an essential micronutrient that regulates a wide range of physiological processes, principally through Zn2+ binding to protein cysteine residues. Despite being critical for modulation of protein function, for the vast majority of the human proteome the cysteine sites subject to regulation by Zn2+ binding remain undefined. Here we develop ZnCPT, a comprehensive and quantitative mapping of the zinc-regulated cysteine proteome. We define 4807 zinc-regulated protein cysteines, uncovering protein families across major domains of biology that are subject to either constitutive or inducible modification by zinc. ZnCPT enables systematic discovery of zinc-regulated structural, enzymatic, and allosteric functional domains. On this basis, we define 52 cancer genetic dependencies subject to zinc regulation, and nominate malignancies sensitive to zinc-induced cytotoxicity. In doing so, we discover a mechanism of zinc regulation over Glutathione Reductase (GSR) that drives cell death in GSR-dependent lung cancers. We provide ZnCPT as a resource for understanding mechanisms of zinc regulation over protein function.

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Section: Resultsmentioning

confidence: 91%

A comprehensive landscape of the zinc-regulated human proteome

Burger,

Mittenbühler,

Xiao

et al. 2024

Preprint

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“…IscU has been shown to interact with cysteine desulfurase IscS and deliver the assembled iron–sulfur cluster to target proteins ( 37 , 38 , 39 , 40 ). In eukaryotic cells, deletion of IscU leads to accumulation of iron in mitochondria ( 63 ).…”

Section: Discussionmentioning

confidence: 99%

“…Among the core iron–sulfur cluster assembly proteins encoded by the housekeeping isc operon, IscS is a cysteine desulfurase that catalyzes desulfurization of L-cysteine and delivers sulfur for iron–sulfur cluster assembly in IscU ( 33 , 34 , 35 , 36 ). IscU is a scaffold protein that assembles iron–sulfur clusters and transfers the assembled clusters to target proteins ( 37 , 38 , 39 , 40 ). IscA was initially characterized as an alternative scaffold protein ( 41 ).…”

mentioning

confidence: 99%

Iron–sulfur cluster assembly scaffold protein IscU is required for activation of ferric uptake regulator (Fur) in Escherichia coli

Purcell,

Fontenot,

Ding

2024

Journal of Biological Chemistry

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“…In such a scheme, two one-electron reduced [2Fe-2S] 1+ clusters, presumably from two different monomers of HBx, are reductively coupled to yield the higher nuclearity [4Fe-4S] cofactor. Currently, it is not known whether this reductive rearrangement to afford a higher nuclearity cofactor is physiologically relevant, but it is noteworthy that analogous transitions have primarily been observed in Fe-S cluster donor proteins, such as IscU and IscA [115][116][117]. This molecular similarity implies that HBx may exhibit the potential to act as a rogue Fe-S cluster donor, a function that may be linked to HBx-mediated oncogenesis.…”

Section: Redox Transformations Of the Hbx Fe-s Clustermentioning

confidence: 97%

The Cryptic Nature of Fe-S Clusters: A Case Study of the Hepatitis B HBx Oncoprotein

Quist,

Chen,

MacNeil

et al. 2023

Inorganics

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Fe-S clusters are ubiquitous inorganic cofactors found in proteins across all domains of life, including viruses. Their prevalence stems from their unique redox and structural plasticity that supports functions ranging from electron transfer and catalysis to stabilization of protein structure. Although the ability of Fe-S clusters to exchange electrons is often functionally crucial, it can also act as an Achilles heel when these cofactors are exposed to oxidizing conditions, often leading to their degradation. This O2 sensitivity has rendered certain Fe-S clusters untraceable, particularly when the nascent proteins are isolated under ambient conditions. As a consequence of this O2 sensitivity, a growing number of proteins with roles in viral infection have been found to harbor Fe-S clusters rather than the annotated Zn2+ cofactor. The enigmatic protein X (HBx) of the Hepatitis B Virus is a multifunctional protein essential for viral replication and development of liver disease. Although HBx has defied biochemical characterization for over forty years, it has been shown to coordinate a redox-active Fe-S cluster that represents a significant feature for establishing its molecular function. The present review narrates the approaches to validate the HBx metallocofactor that can be broadly applied as a guide for uncovering the presence of Fe-S clusters in proteins with non-canonical sequence motifs.

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Native mass spectrometric studies of IscSU reveal a concerted, sulfur-initiated mechanism of iron–sulfur cluster assembly

Abstract: Iron-sulfur (Fe-S) clusters are cofactors essential for life. Though the proteins that function in the assembly of Fe-S clusters are well known, details of the molecular mechanism are less well...

Cited by 15 publications

References 90 publications

A comprehensive landscape of the zinc-regulated human proteome

A comprehensive landscape of the zinc-regulated human proteome

Iron–sulfur cluster assembly scaffold protein IscU is required for activation of ferric uptake regulator (Fur) in Escherichia coli

The Cryptic Nature of Fe-S Clusters: A Case Study of the Hepatitis B HBx Oncoprotein

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