Iron–sulfur cluster biosynthesis

Iron–sulfur (Fe–S) clusters are present in more than 200 different types of enzymes or proteins and constitute one of the most ancient, ubiquitous and structurally diverse classes of biological prosthetic groups. Hence the process of Fe–S cluster biosynthesis is essential to almost all forms of life and is remarkably conserved in prokaryotic and eukaryotic organisms. Three distinct types of Fe–S cluster assembly machinery have been established in bacteria, termed the NIF, ISC and SUF systems, and, in each case, the overall mechanism involves cysteine desulfurase-mediated assembly of transient clusters on scaffold proteins and subsequent transfer of pre-formed clusters to apo proteins. A molecular level understanding of the complex processes of Fe–S cluster assembly and transfer is now beginning to emerge from the combination of in vivo and in vitro approaches. The present review highlights recent developments in understanding the mechanism of Fe–S cluster assembly and transfer involving the ubiquitous U-type scaffold proteins and the potential roles of accessory proteins such as Nfu proteins and monothiol glutaredoxins in the assembly, storage or transfer of Fe–S clusters.

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Mechanism of Iron–Sulfur Cluster Assembly: In the Intimacy of Iron and Sulfur Encounter

Inorganics ◽

10.3390/inorganics8100055 ◽

2020 ◽

Vol 8 (10) ◽

pp. 55

Author(s):

Batoul Srour ◽

Sylvain Gervason ◽

Beata Monfort ◽

Benoit D’Autréaux

Keyword(s):

Cluster Assembly ◽

Cysteine Desulfurase ◽

Iron Sulfur Cluster ◽

Iron Sulfur ◽

Physiological Relevance ◽

Client Proteins ◽

Sulfide Ions ◽

Cluster Biosynthesis

Iron–sulfur (Fe–S) clusters are protein cofactors of a multitude of enzymes performing essential biological functions. Specialized multi-protein machineries present in all types of organisms support their biosynthesis. These machineries encompass a scaffold protein on which Fe–S clusters are assembled and a cysteine desulfurase that provides sulfur in the form of a persulfide. The sulfide ions are produced by reductive cleavage of the persulfide, which involves specific reductase systems. Several other components are required for Fe–S biosynthesis, including frataxin, a key protein of controversial function and accessory components for insertion of Fe–S clusters in client proteins. Fe–S cluster biosynthesis is thought to rely on concerted and carefully orchestrated processes. However, the elucidation of the mechanisms of their assembly has remained a challenging task due to the biochemical versatility of iron and sulfur and the relative instability of Fe–S clusters. Nonetheless, significant progresses have been achieved in the past years, using biochemical, spectroscopic and structural approaches with reconstituted system in vitro. In this paper, we review the most recent advances on the mechanism of assembly for the founding member of the Fe–S cluster family, the [2Fe2S] cluster that is the building block of all other Fe–S clusters. The aim is to provide a survey of the mechanisms of iron and sulfur insertion in the scaffold proteins by examining how these processes are coordinated, how sulfide is produced and how the dinuclear [2Fe2S] cluster is formed, keeping in mind the question of the physiological relevance of the reconstituted systems. We also cover the latest outcomes on the functional role of the controversial frataxin protein in Fe–S cluster biosynthesis.

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Physical and Functional Interactions of a Monothiol Glutaredoxin and an Iron Sulfur Cluster Carrier Protein with the Sulfur-donating Radical S-Adenosyl-l-methionine Enzyme MiaB

Journal of Biological Chemistry ◽

10.1074/jbc.m113.460360 ◽

2013 ◽

Vol 288 (20) ◽

pp. 14200-14211 ◽

Cited By ~ 20

Author(s):

Sylvain Boutigny ◽

Avneesh Saini ◽

Edward E. K. Baidoo ◽

Natasha Yeung ◽

Jay D. Keasling ◽

...

Keyword(s):

Protein Interactions ◽

Carrier Protein ◽

Cluster Assembly ◽

Carrier Proteins ◽

Iron Sulfur Cluster ◽

Iron Sulfur ◽

Initial Cluster ◽

Initial Assembly

The biosynthesis of iron sulfur (FeS) clusters, their trafficking from initial assembly on scaffold proteins via carrier proteins to final incorporation into FeS apoproteins, is a highly coordinated process enabled by multiprotein systems encoded in iscRSUAhscBAfdx and sufABCDSE operons in Escherichia coli. Although these systems are believed to encode all factors required for initial cluster assembly and transfer to FeS carrier proteins, accessory factors such as monothiol glutaredoxin, GrxD, and the FeS carrier protein NfuA are located outside of these defined systems. These factors have been suggested to function both as shuttle proteins acting to transfer clusters between scaffold and carrier proteins and in the final stages of FeS protein assembly by transferring clusters to client FeS apoproteins. Here we implicate both of these factors in client protein interactions. We demonstrate specific interactions between GrxD, NfuA, and the methylthiolase MiaB, a radical S-adenosyl-l-methionine-dependent enzyme involved in the maturation of a subset of tRNAs. We show that GrxD and NfuA physically interact with MiaB with affinities compatible with an in vivo function. We furthermore demonstrate that NfuA is able to transfer its cluster in vitro to MiaB, whereas GrxD is unable to do so. The relevance of these interactions was demonstrated by linking the activity of MiaB with GrxD and NfuA in vivo. We observe a severe defect in in vivo MiaB activity in cells lacking both GrxD and NfuA, suggesting that these proteins could play complementary roles in maturation and repair of MiaB.

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Biogenesis and Transfer of Iron-Sulfur Clusters from Acidithiobacillus ferrooxidans

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.825.198 ◽

2013 ◽

Vol 825 ◽

pp. 198-201 ◽

Cited By ~ 1

Author(s):

Jian She Liu ◽

Lin Qian ◽

Chun Li Zheng

Keyword(s):

Acidithiobacillus Ferrooxidans ◽

Binding Protein ◽

Cluster Assembly ◽

Cysteine Desulfurase ◽

Iron Sulfur Cluster ◽

Iron Sulfur Clusters ◽

Sulfur Cluster ◽

Iron Sulfur ◽

Iron Sulfur Proteins

Iron-sulfur (Fe-S) proteins are ubiquitous and participate in multiple essential functions of life. However, little is currently known about the mechanisms of iron-sulfur biosynthesis and transfer in acidophilic microorganisms. In this study, the IscS, IscU and IscA proteins from Acidithiobacillus ferrooxidans were successfully expressed in Escherichia coli and purified by affinity chromatography. The IscS was a cysteine desulfurase which catalyzes desulfurization of L-cysteine and transfer sulfur for iron-sulfur cluster assembly. Purified IscU did not have an iron-sulfur cluster but could act as a scaffold protein to assemble the [2Fe-2S] cluster in vitro. The IscA was a [4Fe-4S] cluster binding protein, but it also acted as an iron binding protein. Further studies indicated that the iron sulfur clusters could be transferred from pre-assembled scaffold proteins to apo-form iron sulfur proteins, the reconstituted iron sulfur proteins could restore their physiological activities.

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IOP1 Protein Is an External Component of the Human Cytosolic Iron-Sulfur Cluster Assembly (CIA) Machinery and Functions in the MMS19 Protein-dependent CIA Pathway

Journal of Biological Chemistry ◽

10.1074/jbc.m112.416602 ◽

2013 ◽

Vol 288 (23) ◽

pp. 16680-16689 ◽

Cited By ~ 29

Author(s):

Mineaki Seki ◽

Yukiko Takeda ◽

Kazuhiro Iwai ◽

Kiyoji Tanaka

Keyword(s):

Cluster Assembly ◽

Core Complex ◽

Core Component ◽

Iron Sulfur Cluster ◽

Sulfur Cluster ◽

The Core ◽

Iron Sulfur ◽

External Component

The emerging link between iron metabolism and genome integrity is increasingly clear. Recent studies have revealed that MMS19 and cytosolic iron-sulfur cluster assembly (CIA) factors form a complex and have central roles in CIA pathway. However, the composition of the CIA complex, particularly the involvement of the Fe-S protein IOP1, is still unclear. The roles of each component are also largely unknown. Here, we show that MMS19, MIP18, and CIAO1 form a tight “core” complex and that IOP1 is an “external” component of this complex. Although IOP1 and the core complex form a complex both in vivo and in vitro, IOP1 behaves differently in vivo. A deficiency in any core component leads to down-regulation of all of the components. In contrast, IOP1 knockdown does not affect the level of any core component. In MMS19-overproducing cells, other core components are also up-regulated, but the protein level of IOP1 remains unchanged. IOP1 behaves like a target protein in the CIA reaction, like other Fe-S helicases, and the core complex may participate in the maturation process of IOP1. Alternatively, the core complex may catch and hold IOP1 when it becomes mature to prevent its degradation. In any case, IOP1 functions in the MMS19-dependent CIA pathway. We also reveal that MMS19 interacts with target proteins. MIP18 has a role to bridge MMS19 and CIAO1. CIAO1 also binds IOP1. Based on our in vivo and in vitro data, new models of the CIA machinery are proposed.

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Contribution of Cysteine Desulfurase (NifS Protein) to the Biotin Synthase Reaction of Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.182.10.2879-2885.2000 ◽

2000 ◽

Vol 182 (10) ◽

pp. 2879-2885 ◽

Cited By ~ 25

Author(s):

Tatsuya Kiyasu ◽

Akira Asakura ◽

Yoshie Nagahashi ◽

Tatsuo Hoshino

Keyword(s):

Escherichia Coli ◽

Reaction System ◽

Cysteine Desulfurase ◽

Biotin Synthase ◽

Iron Sulfur Cluster ◽

Free System ◽

E Coli ◽

Iron Sulfur

ABSTRACT The contribution of cysteine desulfurase, the NifS protein ofKlebsiella pneumoniae and the IscS protein ofEscherichia coli, to the biotin synthase reaction was investigated in in vitro and in vivo reaction systems with E. coli. When the nifS and nifU genes ofK. pneumoniae were coexpressed in E. coli, NifS and NifU proteins in complex (NifU/S complex) and NifU monomer forms were observed. Both the NifU/S complex and the NifU monomer stimulated the biotin synthase reaction in the presence of l-cysteine in an in vitro reaction system. The NifU/S complex enhanced the production of biotin from dethiobiotin by the cells growing in an in vivo reaction system. Moreover, the IscS protein of E. colistimulated the biotin synthase reaction in the presence ofl-cysteine in the cell-free system. These results strongly suggest that cysteine desulfurase participates in the biotin synthase reaction, probably by supplying sulfur to the iron-sulfur cluster of biotin synthase.

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Characterization and Reconstitution of Human Lipoyl Synthase (LIAS) Supports ISCA2 and ISCU as Primary Cluster Donors and an Ordered Mechanism of Cluster Assembly

International Journal of Molecular Sciences ◽

10.3390/ijms22041598 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1598

Author(s):

Amber L. Hendricks ◽

Christine Wachnowsky ◽

Brian Fries ◽

Insiya Fidai ◽

James A. Cowan

Keyword(s):

Cluster Assembly ◽

Paramagnetic Resonance ◽

Iron Sulfur Cluster ◽

Sulfur Transfer ◽

Disease States ◽

Isolation And Characterization ◽

Iron Sulfur ◽

Natural Iron ◽

Lipoyl Synthase

Lipoyl synthase (LIAS) is an iron–sulfur cluster protein and a member of the radical S-adenosylmethionine (SAM) superfamily that catalyzes the final step of lipoic acid biosynthesis. The enzyme contains two [4Fe–4S] centers (reducing and auxiliary clusters) that promote radical formation and sulfur transfer, respectively. Most information concerning LIAS and its mechanism has been determined from prokaryotic enzymes. Herein, we detail the expression, isolation, and characterization of human LIAS, its reactivity, and evaluation of natural iron–sulfur (Fe–S) cluster reconstitution mechanisms. Cluster donation by a number of possible cluster donor proteins and heterodimeric complexes has been evaluated. [2Fe–2S]-cluster-bound forms of human ISCU and ISCA2 were found capable of reconstituting human LIAS, such that complete product turnover was enabled for LIAS, as monitored via a liquid chromatography–mass spectrometry (LC–MS) assay. Electron paramagnetic resonance (EPR) studies of native LIAS and substituted derivatives that lacked the ability to bind one or the other of LIAS’s two [4Fe–4S] clusters revealed a likely order of cluster addition, with the auxiliary cluster preceding the reducing [4Fe–4S] center. These results detail the trafficking of Fe–S clusters in human cells and highlight differences with respect to bacterial LIAS analogs. Likely in vivo Fe–S cluster donors to LIAS are identified, with possible connections to human disease states, and a mechanistic ordering of [4Fe–4S] cluster reconstitution is evident.

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