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Mechanistic studies of a novel C-S lyase in ergothioneine biosynthesis: the involvement of a sulfenic acid intermediate.

Song H, Hu W, Naowarojna N, Her AS, Wang S, Desai R, Qin L, Chen X, Liu P - Sci Rep (2015)

Bottom Line: In ergothioneine biosynthesis, the combination of a mononuclear non-heme iron enzyme catalyzed oxidative C-S bond formation reaction and a PLP-mediated C-S lyase (EgtE) reaction results in a net sulfur transfer from cysteine to histidine side-chain.This demonstrates a new sulfur transfer strategy in the biosynthesis of sulfur-containing natural products.Results from our biochemical characterizations support the assignment of sulfoxide 4 as the native EgtE substrate and the involvement of a sulfenic acid intermediate in the ergothioneine C-S lyase reaction.

View Article: PubMed Central - PubMed

Affiliation: Departments of Chemistry, Boston University, Boston, MA 02215, USA.

ABSTRACT
Ergothioneine is a histidine thio-derivative isolated in 1909. In ergothioneine biosynthesis, the combination of a mononuclear non-heme iron enzyme catalyzed oxidative C-S bond formation reaction and a PLP-mediated C-S lyase (EgtE) reaction results in a net sulfur transfer from cysteine to histidine side-chain. This demonstrates a new sulfur transfer strategy in the biosynthesis of sulfur-containing natural products. Due to difficulties associated with the overexpression of Mycobacterium smegmatis EgtE protein, the proposed EgtE functionality remained to be verified biochemically. In this study, we have successfully overexpressed and purified M. smegmatis EgtE enzyme and evaluated its activities under different in vitro conditions: C-S lyase reaction using either thioether or sulfoxide as a substrate in the presence or absence of reductants. Results from our biochemical characterizations support the assignment of sulfoxide 4 as the native EgtE substrate and the involvement of a sulfenic acid intermediate in the ergothioneine C-S lyase reaction.

No MeSH data available.


Related in: MedlinePlus

Two different ergothioneine biosynthetic pathways.(A) The M. Smegmatis ergothioneine biosyntetic pathway (EgtA-EgtE catalysis). (B) The fungal N.crassa ergothioneine biosynthetic pathway (Egt1).
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f1: Two different ergothioneine biosynthetic pathways.(A) The M. Smegmatis ergothioneine biosyntetic pathway (EgtA-EgtE catalysis). (B) The fungal N.crassa ergothioneine biosynthetic pathway (Egt1).

Mentions: Glutathione, one of the most abundant natural thiols inside the cells (up to 10 mM), plays a key role in buffering the intracellular redox-state. In many organisms, there exists another important thiol, ergothioneine, which is a thio-imidazole containing amino acid (5, Fig. 1)123 Different from glutathione, the predominant form of ergothioneine is its thione form (5b, Fig. 1). As a result, ergothioneine’s reduction potential (E0 = −0.06 V)2 is significantly higher than that of glutathione (E0 = −0.24 V)45 Humans do not synthesize ergothioneine. However, through an ergothioneine-specific transporter (OCTN1), we enrich ergothioneine from our diets to mM concentrations in many parts of our body6, including liver, kidneys, central nervous system, erythrocytes, eye lenses, and seminal fluids278910. Ergothioneine has many beneficial roles to human health241112, especially its role as an effective scavenger for reactive oxidative species (ROS), including singlet oxygen, hydroxyl, peroxyl, peroxynitrite (ONOO-), nitrosoperoxycarbonate (ONOOCO2−), and carbonate radicals13141516.


Mechanistic studies of a novel C-S lyase in ergothioneine biosynthesis: the involvement of a sulfenic acid intermediate.

Song H, Hu W, Naowarojna N, Her AS, Wang S, Desai R, Qin L, Chen X, Liu P - Sci Rep (2015)

Two different ergothioneine biosynthetic pathways.(A) The M. Smegmatis ergothioneine biosyntetic pathway (EgtA-EgtE catalysis). (B) The fungal N.crassa ergothioneine biosynthetic pathway (Egt1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493562&req=5

f1: Two different ergothioneine biosynthetic pathways.(A) The M. Smegmatis ergothioneine biosyntetic pathway (EgtA-EgtE catalysis). (B) The fungal N.crassa ergothioneine biosynthetic pathway (Egt1).
Mentions: Glutathione, one of the most abundant natural thiols inside the cells (up to 10 mM), plays a key role in buffering the intracellular redox-state. In many organisms, there exists another important thiol, ergothioneine, which is a thio-imidazole containing amino acid (5, Fig. 1)123 Different from glutathione, the predominant form of ergothioneine is its thione form (5b, Fig. 1). As a result, ergothioneine’s reduction potential (E0 = −0.06 V)2 is significantly higher than that of glutathione (E0 = −0.24 V)45 Humans do not synthesize ergothioneine. However, through an ergothioneine-specific transporter (OCTN1), we enrich ergothioneine from our diets to mM concentrations in many parts of our body6, including liver, kidneys, central nervous system, erythrocytes, eye lenses, and seminal fluids278910. Ergothioneine has many beneficial roles to human health241112, especially its role as an effective scavenger for reactive oxidative species (ROS), including singlet oxygen, hydroxyl, peroxyl, peroxynitrite (ONOO-), nitrosoperoxycarbonate (ONOOCO2−), and carbonate radicals13141516.

Bottom Line: In ergothioneine biosynthesis, the combination of a mononuclear non-heme iron enzyme catalyzed oxidative C-S bond formation reaction and a PLP-mediated C-S lyase (EgtE) reaction results in a net sulfur transfer from cysteine to histidine side-chain.This demonstrates a new sulfur transfer strategy in the biosynthesis of sulfur-containing natural products.Results from our biochemical characterizations support the assignment of sulfoxide 4 as the native EgtE substrate and the involvement of a sulfenic acid intermediate in the ergothioneine C-S lyase reaction.

View Article: PubMed Central - PubMed

Affiliation: Departments of Chemistry, Boston University, Boston, MA 02215, USA.

ABSTRACT
Ergothioneine is a histidine thio-derivative isolated in 1909. In ergothioneine biosynthesis, the combination of a mononuclear non-heme iron enzyme catalyzed oxidative C-S bond formation reaction and a PLP-mediated C-S lyase (EgtE) reaction results in a net sulfur transfer from cysteine to histidine side-chain. This demonstrates a new sulfur transfer strategy in the biosynthesis of sulfur-containing natural products. Due to difficulties associated with the overexpression of Mycobacterium smegmatis EgtE protein, the proposed EgtE functionality remained to be verified biochemically. In this study, we have successfully overexpressed and purified M. smegmatis EgtE enzyme and evaluated its activities under different in vitro conditions: C-S lyase reaction using either thioether or sulfoxide as a substrate in the presence or absence of reductants. Results from our biochemical characterizations support the assignment of sulfoxide 4 as the native EgtE substrate and the involvement of a sulfenic acid intermediate in the ergothioneine C-S lyase reaction.

No MeSH data available.


Related in: MedlinePlus