Tryptophan Lyase (NosL): A Cornucopia of 5′-Deoxyadenosyl Radical Mediated Transformations

Bhandari, Dhananjay M; Fedoseyenko, Dmytro; Begley, Tadhg P.

doi:10.1021/jacs.6b06139

Cited by 40 publications

(36 citation statements)

References 25 publications

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“…Under reducing conditions, the hydrogen atom may be added as a proton followed by addition of an electron via the [4Fe-4S] cluster. Guided by previous data in which addition of a 5 0 -dAdo radical and a hydrogen atom to a substrate was observed at a carbonyl group or at a C=C double bond [10,11], we predict that Viperin catalyzes addition of a 5 0 -dAdo radical and a hydrogen atom to a C=C or C=O bond in the uracil unit of UDP-glucose. Indeed, docking experiments using UDP-glucose ( Fig.…”

Section: Discussionsupporting

confidence: 57%

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The radical‐SAM enzyme Viperin catalyzes reductive addition of a 5′‐deoxyadenosyl radical to UDP‐glucose in vitro

et al. 2017

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Viperin, a radical-S-adenosylmethionine (SAM) enzyme conserved from fungi to humans, can restrict replication of many viruses. Neither the molecular mechanism underlying the antiviral activity of Viperin, nor its exact physiological function, is understood: most importantly, no radical-SAM activity has been discovered for Viperin. Here, using electron paramagnetic resonance (EPR) spectroscopy, mass spectrometry, and NMR spectroscopy, we show that uridine diphosphate glucose (UDP-glucose) is a substrate of a fungal Viperin (58% pairwise identity with human Viperin at the amino acid level) in vitro. Structural homology modeling and docking experiments reveal a highly conserved binding pocket in which the position of UDP-glucose is consistent with our experimental data regarding catalytic addition of a 5'-deoxyadenosyl radical and a hydrogen atom to UDP-glucose.

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Section: Discussionsupporting

confidence: 57%

“…). In few cases, the 5′‐dAdo radical is added to a C=C or C=O double bond in a substrate via an addition/elimination reaction , and in one case it is added reductively to a C=C double bond in a substrate to form a product .…”

mentioning

confidence: 99%

The radical‐SAM enzyme Viperin catalyzes reductive addition of a 5′‐deoxyadenosyl radical to UDP‐glucose in vitro

et al. 2017

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“…After H-atom abstraction and carboxyl fragment migration, 3-methylindolic acid is formed. Interestingly, NosL has been shown to be a highly promiscuous enzyme able to modify a broad range of tryptophan analogs (Bhandari et al, 2015 , 2016 ; Ji et al, 2015 , 2016 ; Ding et al, 2016a ; Qianzhu et al, 2016 ) allowing a detailed mechanistic study of this unique enzyme.…”

Section: Complex Rearrangements In Rippsmentioning

confidence: 99%

Radical SAM Enzymes in the Biosynthesis of Ribosomally Synthesized and Post-translationally Modified Peptides (RiPPs)

2017

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Ribosomally-synthesized and post-translationally modified peptides (RiPPs) are a large and diverse family of natural products. They possess interesting biological properties such as antibiotic or anticancer activities, making them attractive for therapeutic applications. In contrast to polyketides and non-ribosomal peptides, RiPPs derive from ribosomal peptides and are post-translationally modified by diverse enzyme families. Among them, the emerging superfamily of radical SAM enzymes has been shown to play a major role. These enzymes catalyze the formation of a wide range of post-translational modifications some of them having no counterparts in living systems or synthetic chemistry. The investigation of radical SAM enzymes has not only illuminated unprecedented strategies used by living systems to tailor peptides into complex natural products but has also allowed to uncover novel RiPP families. In this review, we summarize the current knowledge on radical SAM enzymes catalyzing RiPP post-translational modifications and discuss their mechanisms and growing importance notably in the context of the human microbiota.

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“…Although these side activities have not been previously reported for other RS-SPASM proteins, they are not uncommon among RS proteins in general. For instance, a recent report on NosL, a tryptophan lyase, demonstrated the incorporation of dAdo into the double bond of a non-native indole methyl acrylate substrate (17).…”

Section: Discussionmentioning

confidence: 99%

“…The enzyme's ability to control and direct the highly oxidative dAdo⅐ is paramount to preventing inactivation of the enzyme or the formation of unwanted byproducts. However, by loosening the restrictions of the enzyme on its control of the dAdo⅐, new and intriguing derivatives of natural products can be formed (17,18).…”

mentioning

confidence: 99%

Mechanistic elucidation of the mycofactocin-biosynthetic radical S-adenosylmethionine protein, MftC

Khaliullin

Ayikpoe

Tuttle

et al. 2017

Journal of Biological Chemistry

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Ribosomally synthesized and posttranslationally modified peptide (RiPP) pathways produce a diverse array of natural products. A subset of these pathways depends on radical -adenosylmethionine proteins to modify the RiPP-produced peptide. Mycofactocin biosynthesis is one example of an-adenosylmethionine protein-dependent RiPP pathway. Recently, it has been shown that MftC catalyzes the oxidative decarboxylation of the C-terminal tyrosine (Tyr-30) on the mycofactocin precursor peptide MftA; however, this product has not been verified by techniques other than MS. Herein, we provide a more detailed study of MftC catalysis and report a revised mechanism for MftC chemistry. We show that MftC catalyzes the formation of two isomeric products. Using a combination of MS, isotope labeling, and H andC NMR techniques, we established that the major product, MftA*, is a tyramine-valine-cross-linked peptide formed by MftC through two -adenosylmethionine-dependent turnovers. In addition, we show that the hydroxyl group on MftA Tyr-30 is required for MftC catalysis. Furthermore, we show that a substitution in the penultimate MftA Val-29 position causes the accumulation of an MftA** minor product. TheH NMR spectrum indicates that this minor product contains an αβ-unsaturated bond that likely arises from an aborted intermediate of MftA* synthesis. The finding that MftA* is the major product formed during MftC catalysis could have implications for the further elucidation of mycofactocin biosynthesis.

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Tryptophan Lyase (NosL): A Cornucopia of 5′-Deoxyadenosyl Radical Mediated Transformations

Cited by 40 publications

References 25 publications

The radical‐SAM enzyme Viperin catalyzes reductive addition of a 5′‐deoxyadenosyl radical to UDP‐glucose in vitro

The radical‐SAM enzyme Viperin catalyzes reductive addition of a 5′‐deoxyadenosyl radical to UDP‐glucose in vitro

Radical SAM Enzymes in the Biosynthesis of Ribosomally Synthesized and Post-translationally Modified Peptides (RiPPs)

Mechanistic elucidation of the mycofactocin-biosynthetic radical S-adenosylmethionine protein, MftC

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