Proof of the presence of racemic forms of arylglycerol-Β-aryl ether structure in lignin: studies on the stereo structure of lignin by ozonation

Akiyama, Takuya; Magara, Kengo; Matsumoto, Yuji; Meshitsuka, Gyosuke; Ishizu, Atsushi; Lundquist, Knut

doi:10.1007/bf00776407

Cited by 47 publications

(29 citation statements)

References 2 publications

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“…It has been assumed that native lignin is optically inactive, and the presence of racemic forms of arylglycerol-␤-aryl ether in lignin was recently indicated (3). In order to investigate the enantioselectivity of LigF and LigE, after the incubation of MPHPV with purified LigF in the presence of glutathione, crude LigE enzyme was added to a reaction mixture.…”

Section: Resultsmentioning

confidence: 99%

Roles of the Enantioselective Glutathione S -Transferases in Cleavage of β-Aryl Ether

et al. 2003

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Cleavage of the ␤-aryl ether linkage is the most important process in lignin degradation. Here we characterize the three tandemly located glutathione S-transferase (GST) genes, ligF, ligE, and ligG, from lowmolecular-weight lignin-degrading Sphingomonas paucimobilis SYK-6, and we describe the actual roles of these genes in the ␤-aryl ether cleavage. Based on the identification of the reaction product by electrospray ionization-mass spectrometry, a model compound of ␤-aryl ether, ␣-(2-methoxyphenoxy)-␤-hydroxypropiovanillone (MPHPV), was transformed by LigF or LigE to guaiacol and ␣-glutathionyl-␤-hydroxypropiovanillone (GS-HPV). This result suggested that LigF and LigE catalyze the nucleophilic attack of glutathione on the carbon atom at the ␤ position of MPHPV. High-pressure liquid chromatography-circular dichroism analysis indicated that LigF and LigE each attacked a different enantiomer of the racemic MPHPV preparation. The ligG gene product specifically catalyzed the elimination of glutathione from GS-HPV generated by the action of LigF. This reaction then produces an achiral compound, ␤-hydroxypropiovanillone, which is further degraded by this strain. Disruption of the ligF, ligE, and ligG genes in SYK-6 showed that ligF is essential to the degradation of one of the MPHPV enantiomers, and the alternative activities which metabolize the substrates of LigE and LigG are present in this strain.

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Section: Resultsmentioning

confidence: 99%

Roles of the Enantioselective Glutathione S -Transferases in Cleavage of β-Aryl Ether

et al. 2003

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“…Various fragments carefully excised from lignins show no detectable optical activity-they are racemic (Freudenberg et al, 1965;Ralph et al, 1999;Akiyama et al, 2000). To explain this observation, one must envision a second array of dirigent proteins with the opposite stereo-and regiospecificity to generate a racemic mixture of coupling products in the lignin molecule, a notion proposed by the dirigent protein advocates (Lewis and Davin, 1998;Davin and Lewis, 2000).…”

Section: The Lignification Dilemmamentioning

confidence: 99%

Lignin Formation in Plants. The Dilemma of Linkage Specificity

2001

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“…Its degradation by microbes is an essential process in the carbon cycle on Earth. Lignin has various intermolecular linkages between phenylpropane units and contains a number of asymmetric carbons, but it is assumed to be optically inactive (2). Microbes, specifically bacteria, appear to have a variety of stereospecific enzymes which degrade stereoisomers of lignin substructures, but little is known about the stereochemistry of microbial lignin catabolism (10).…”

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Identification of Three Alcohol Dehydrogenase Genes Involved in the Stereospecific Catabolism of Arylglycerol-β-Aryl Ether by Sphingobium sp. Strain SYK-6

Sato

Moriuchi

Hishiyama

et al. 2009

Appl Environ Microbiol

101

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Degradation of arylglycerol-␤-aryl ether is the most important process in bacterial lignin catabolism. Sphingobium sp. strain SYK-6 degrades guaiacylglycerol-␤-guaiacyl ether (GGE) to ␣-(2-methoxyphenoxy)-␤-hydroxypropiovanillone (MPHPV), and then the ether linkage of MPHPV is cleaved to generate ␣-glutathionyl-␤-hydroxypropiovanillone (GS-HPV) and guaiacol. We have characterized three enantioselective glutathione S-transferase genes, including two genes that are involved in the ether cleavage of two enantiomers of MPHPV and one gene that is involved in the elimination of glutathione from a GS-HPV enantiomer. However, the first step in the degradation of four different GGE stereoisomers has not been characterized. In this study, three alcohol dehydrogenase genes, ligL, ligN, and ligO, which conferred GGE transformation activity in Escherichia coli, were isolated from SYK-6 and characterized, in addition to the previously cloned ligD gene. The levels of amino acid sequence identity of the four GGE dehydrogenases, which belong to the short-chain dehydrogenase/ reductase family, ranged from 32% to 39%. Each gene was expressed in E. coli, and the stereospecificities of the gene products with the four GGE stereoisomers were determined by using chiral high-performance liquid chromatography with recently synthesized authentic enantiopure GGE stereoisomers. LigD and LigO converted (␣R,␤S)-GGE and (␣R,␤R)-GGE into (␤S)-MPHPV and (␤R)-MPHPV, respectively, while LigL and LigN transformed (␣S,␤R)-GGE and (␣S,␤S)-GGE to (␤R)-MPHPV and (␤S)-MPHPV, respectively. Disruption of the genes indicated that ligD is essential for the degradation of (␣R,␤S)-GGE and (␣R,␤R)-GGE and that both ligL and ligN contribute to the degradation of the two other GGE stereoisomers.

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Proof of the presence of racemic forms of arylglycerol-Β-aryl ether structure in lignin: studies on the stereo structure of lignin by ozonation

Cited by 47 publications

References 2 publications

Roles of the Enantioselective Glutathione S -Transferases in Cleavage of β-Aryl Ether

Roles of the Enantioselective Glutathione S -Transferases in Cleavage of β-Aryl Ether

Lignin Formation in Plants. The Dilemma of Linkage Specificity

Identification of Three Alcohol Dehydrogenase Genes Involved in the Stereospecific Catabolism of Arylglycerol-β-Aryl Ether by Sphingobium sp. Strain SYK-6

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