In vivo formation of C?S bonds in biotin. An example of radical chemistry under reducing conditions

Marquet, Andrée; Florentin, D.; Ploux, Olivier; Bui, Bernadette Tse Sum

doi:10.1002/(sici)1099-1395(199808/09)11:8/9<529::aid-poc44>3.0.co;2-7

Cited by 16 publications

(5 citation statements)

References 34 publications

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“…This, however, is not the case for more than 13,500 known radical S -adenosyl-L-methionine (SAM) enzymes (98, 99). Radical SAM enzymes employ the tunable, versatile [4Fe4S] cluster cofactor to catalyze essential biochemical reactions, acting on a variety of substrates in multiple metabolic pathways, including repair of UV-induced DNA damage and modification of tRNAs (30, 98, 100–102). These repair proteins, unlike those that carry out redox signaling, contain ferredoxin-like clusters coordinated by three cysteines, which cycle between the [4Fe4S] + and [4Fe4S] 2+ states during activity.…”

Section: [4fe4s] Proteins In Nucleic Acid Processing and Repairmentioning

confidence: 99%

Redox Chemistry in the Genome: Emergence of the [4Fe4S] Cofactor in Repair and Replication

Barton

Silva

O’Brien

2019

Annu. Rev. Biochem.

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Many DNA-processing enzymes have been shown to contain a [4Fe4S] cluster, a common redox cofactor in biology. We find using DNA electrochemistry that binding of the DNA polyanion promotes a negative shift in [4Fe4S] cluster potential, which corresponds thermodynamically to ~ 500-fold increase in DNA binding affinity for the oxidized [4Fe4S]3+ cluster versus the reduced [4Fe4S]2+ cluster. This redox switch can be activated from a distance using DNA charge transport chemistry. DNA-processing proteins containing the [4Fe4S] cluster are enumerated with possible roles for the redox switch, highlighted. A model is described where repair proteins may signal one another using DNA-mediated charge transport as a first step in their search for lesions. The redox switch in eukaryotic DNA primases appears to regulate polymerase handoff, and in DNA polymerase δ, the redox switch provides a means to modulate replication in response to oxidative stress. Thus we describe redox signaling interactions of DNA-processing [4Fe4S] enzymes as well as the most interesting potential players to consider in delineating new DNA-mediated redox signaling networks.

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Section: [4fe4s] Proteins In Nucleic Acid Processing and Repairmentioning

confidence: 99%

Redox Chemistry in the Genome: Emergence of the [4Fe4S] Cofactor in Repair and Replication

Barton

Silva

O’Brien

2019

Annu. Rev. Biochem.

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“…They all depend on the cofactor adenosylmethionine (AdoMet), an evolutionary precursor of adenosylcobalamine [66]. These enzymes are pyruvate:formate lyase (PFL) [67,68], anaerobic ribonucleotide reductase (ARNR) [69], both of E. coli, lysine 2,3‐amino mutase (LAM) from Clostridium subliminale [70], and biotin synthase (BS) from E. coli [71,72]. It was thought that radical formation is initiated for PFL, ARNR, LAM, and BS by the interaction of a [4Fe−4S] cluster µ 3 sulfide with AdoMet to form the adenosyl radical and methionine, as shown schematically in Fig.…”

Section: Fe–s Clusters As Participants In Reactionsmentioning

confidence: 99%

“…Biotin synthase [71,72] is a special case inasmuch as a cluster sulfide not only participates in the reaction with AdoMet, but actually is removed from the 4Fe cluster and attached to dethiobiotin in a ’sacrificial’ reaction. The step of interest in the context of this article is the insertion of sulfur into dethiobiotin ( Fig.…”

Section: Fe–s Clusters As Participants In Reactionsmentioning

confidence: 99%

A tribute to sulfur

Beinert

2000

European Journal of Biochemistry

138

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Recent progress in a number of areas of biochemistry and biology has drawn attention to the critical importance of sulfur in the biosynthesis of vital cofactors and active sites in proteins, and in the complex reaction mechanisms often involved. This brief review is intended as a broad overview of this currently rapidly moving field of sulfur biochemistry, for those who are interested or are involved in one or the other aspect of it, a synopsis by one who has stumbled into this field from several directions in the course of time. Only for iron are metal± sulfur relationships discussed in detail, as the iron±sulfur subfield is one of the most active areas.

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“…Biotin synthase (BS) 1 is an S -adenosyl-L-methionine (AdoMet) radical enzyme that catalyzes the oxidative addition of a sulfur atom between the C6 methylene and C9 methyl groups of dethiobiotin (DTB), generating the thiophane ring of biotin (1–3). In our working mechanism (Figure 1A), catalysis is initiated by one-electron reduction of AdoMet sulfonium, generating methionine and a 5′-deoxy-adenosyl radical (dA•).…”

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Reduction of the [2Fe–2S] Cluster Accompanies Formation of the Intermediate 9-Mercaptodethiobiotin in Escherichia coli Biotin Synthase

et al. 2011

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Biotin synthase catalyzes the conversion of dethiobiotin (DTB) to biotin through the oxidative addition of sulfur between two saturated carbon atoms, generating a thiophane ring fused to the existing ureido ring. Biotin synthase is a member of the Radical SAM superfamily, composed of enzymes that reductively cleave S-adenosyl-L-methionine (SAM or AdoMet) to generate a 5′-deoxyadenosyl radical that can abstract unactivated hydrogen atoms from a variety of organic substrates. In biotin synthase, abstraction of a hydrogen atom from the C9 methyl group of DTB would result in formation of a dethiobiotinyl methylene carbon radical, which is then quenched by a sulfur atom to form a new carbon-sulfur bond in the intermediate 9-mercaptodethiobiotin (MDTB). We have proposed that this sulfur atom is the μ-sulfide of a [2Fe-2S]2+ cluster found near DTB in the enzyme active site. In the present work, we show that formation of MDTB is accompanied by stoichiometric generation of a paramagnetic FeS cluster. The electron paramagnetic resonance (EPR) spectrum is modeled as a 2:1 mixture of components attributable to different forms of a [2Fe-2S]+ cluster, possibly distinguished by slightly different coordination environments. Mutation of Arg260, one of the ligands to the [2Fe-2S] cluster, causes a distinctive change in the EPR spectrum. Furthermore, magnetic coupling of the unpaired electron with 14N from Arg260, detectable by electron spin envelope modulation (ESEEM) spectroscopy, is observed in WT enzyme but not in the Arg260Met mutant enzyme. Both results indicate that the paramagnetic FeS cluster formed during catalytic turnover is a [2Fe-2S]+ cluster, consistent with a mechanism in which the [2Fe-2S]2+ cluster simultaneously provides and oxidizes sulfide during carbon-sulfur bond formation.

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In vivo formation of C?S bonds in biotin. An example of radical chemistry under reducing conditions

Cited by 16 publications

References 34 publications

Redox Chemistry in the Genome: Emergence of the [4Fe4S] Cofactor in Repair and Replication

Redox Chemistry in the Genome: Emergence of the [4Fe4S] Cofactor in Repair and Replication

A tribute to sulfur

Reduction of the [2Fe–2S] Cluster Accompanies Formation of the Intermediate 9-Mercaptodethiobiotin in Escherichia coli Biotin Synthase

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