Identification and functional expression of genes encoding flavonoid <scp>O</scp>‐ and <scp>C</scp>‐glycosidases in intestinal bacteria

Braune, Annett; Engst, Wolfram; Blaut, Michaël

doi:10.1111/1462-2920.12864

Cited by 60 publications

(42 citation statements)

References 44 publications

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“…43 Another type of flavonoid O-glycosidase, which consists of 2 proteins, has been identified in Eubacterium cellulosolvens and the Lachnospiraceae strain CG19-1. 44 These enzymes lack similarity to known b-glycosidases and presumably deglycosylation involves an unusual redox-assisted mechanism.…”

Section: Deglycosylation Of Flavonoidsmentioning

confidence: 99%

“…33,37 In E. cellulosolvens, an enzyme system of 5 proteins affords the deglycosylation of C-coupled flavone and isoflavone glucosides. 44 Two of these 5 proteins are sufficient to catalyze the unusual deglycosylation of corresponding flavonoid O-glucosides mentioned above. The majority of the identified C-glucosidecleaving bacteria also act on the corresponding O-coupled glucosides.…”

Section: Dehydroxylation Flavonesmentioning

confidence: 99%

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Bacterial species involved in the conversion of dietary flavonoids in the human gut

2016

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The gut microbiota plays a crucial role in the conversion of dietary flavonoids and thereby affects their health-promoting effects in the human host. The identification of the bacteria involved in intestinal flavonoid conversion has gained increasing interest. This review summarizes available information on the so far identified human intestinal flavonoid-converting bacterial species and strains as well as their enzymes catalyzing the underlying reactions. The majority of described species involved in flavonoid transformation are capable of carrying out the O-deglycosylation of flavonoids. Other bacteria cleave the less common flavonoid-C-glucosides and/or further degrade the aglycones of flavonols, flavanonols, flavones, flavanones, dihydrochalcones, isoflavones and monomeric flavan-3-ols. To increase the currently limited knowledge in this field, identification of flavonoid-converting bacteria should be continued using culture-dependent screening or isolation procedures and molecular approaches based on sequence information of the involved enzymes.

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Section: Deglycosylation Of Flavonoidsmentioning

confidence: 99%

Section: Dehydroxylation Flavonesmentioning

confidence: 99%

Bacterial species involved in the conversion of dietary flavonoids in the human gut

2016

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“…The protein band representing the taxifolin-isomerizing enzyme was excised from the gel following SDS-PAGE with the purified enzyme. Tryptic in-gel digestion of the protein, mass spectrometric analysis of the resulting peptides, and de novo sequencing were performed as described previously (23).…”

Section: Chemicals (ϯ)-Taxifolin and (ϯ)mentioning

confidence: 99%

Chalcone Isomerase from Eubacterium ramulus Catalyzes the Ring Contraction of Flavanonols

et al. 2016

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The enzyme catalyzing the ring-contracting conversion of the flavanonol taxifolin to the auronol alphitonin in the course of flavonoid degradation by the human intestinal anaerobe Eubacterium ramulus was purified and characterized. It stereospecifically catalyzed the isomerization of (؉)-taxifolin but not that of (؊)-taxifolin. The K m for (؉)-taxifolin was 6.4 ؎ 0.8 M, and the V max was 108 ؎ 4 mol min ؊1 (mg protein) ؊1 . The enzyme also isomerized (؉)-dihydrokaempferol, another flavanonol, to maesopsin. Inspection of the encoding gene revealed its complete identity to that of the gene encoding chalcone isomerase (CHI) from E. ramulus. Based on the reported X-ray crystal structure of CHI (M. Gall et al., Angew Chem Int Ed 53:1439 -1442, 2014, http://dx.doi.org/10.1002/anie.201306952), docking experiments suggest the substrate binding mode of flavanonols and their stereospecific conversion. Mutation of the active-site histidine (His33) to alanine led to a complete loss of flavanonol isomerization by CHI, which indicates that His33 is also essential for this activity. His33 is proposed to mediate the stereospecific abstraction of a proton from the hydroxymethylene carbon of the flavanonol C-ring followed by ring opening and recyclization. A flavanonol-isomerizing enzyme was also identified in the flavonoid-converting bacterium Flavonifractor plautii based on its 50% sequence identity to the CHI from E. ramulus. IMPORTANCE Chalcone isomerase was known to be involved in flavone/flavanone conversion by the human intestinal bacterium E. ramulus.Here we demonstrate that this enzyme moreover catalyzes a key step in the breakdown of flavonols/flavanonols. Thus, a single isomerase plays a dual role in the bacterial conversion of dietary bioactive flavonoids. The identification of a corresponding enzyme in the human intestinal bacterium F. plautii suggests a more widespread occurrence of this isomerase in flavonoid-degrading bacteria. F lavonoids represent a major group of plant-derived polyphenolic compounds and have been implicated in beneficial effects on human health (1-4). The flavonoids are classified into several subgroups, which include, among others, flavonols, flavanonols, flavones, flavanones, and chalcones. Quercetin (Fig. 1) is a highly abundant dietary flavonoid that shows a broad range of biological activities. Thus, this flavonol has been intensively studied with respect to its role in disease prevention and use in therapy (5-7). The effects of quercetin and other flavonoids depend on how they are metabolized in the human body, including their conversion by intestinal bacteria (8). Beside deglycosylation and deconjugation, intestinal bacteria are also able to further transform the resulting flavonoid aglycones. However, knowledge about the corresponding bacterial species and, in particular, the enzymes involved is still limited.Eubacterium ramulus and Flavonifractor plautii (formerly Clostridium orbiscindens) are human intestinal bacteria that have been demonstrated to cleave the central heterocyc...

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“…MANG, deglycosylation of mangiferin (xanthone C-glucoside) is catalyzed by at least two partially purified protein fractions, reduced nicotinamide adenine dinucleotide (NADH), diaphorase, dithiothreitol, Mn 2+ and uncharacterized low molecular cofactor. 9,10) In strain CG19-1, the enzymatic activity of puerarin deglycosylation is increased by adding oxidized form of nicotinamide adenine dinucleotide (NAD + ) and Mn 2+ to the cell-free extract. 11) In addition, two puerarin-induced proteins (DfgC, DfgD) that catalyze O-deglycosylation of daidzin but not C-deglycosylation are determined.…”

Section: Introductionmentioning

confidence: 99%

Expression and Characterization of the Human Intestinal Bacterial Enzyme Which Cleaves the C-Glycosidic Bond in 3″-Oxo-puerarin

Nakamura

Zhu

Komatsu

et al. 2019

Biological & Pharmaceutical Bulletin

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Puerarin (daidzein 8-C-glucoside) is an isoflavone C-glucoside contained in the roots of Pueraria lobata OHWI. We have previously isolated the human intestinal bacterium, strain PUE, which metabolizes puerarin to daidzein, though the enzyme which cleaves C-glycosidic bond has not been clarified. Here, we identified one of the intermediates of enzymatic puerarin C-deglycosylation reaction as 3″-oxo-puerarin (1): C-3 in the glucose moiety connecting to hydroxyl is oxidized to ketone group. 1 was easily isomerized to the mixture of 1, 2″-oxo-puerarin (2a) and cyclic acetal (2b) of 2a in non-enzymatic condition. We identified the putative puerarin-metabolizing operon of strain PUE composed of 8 genes (dgpA-H). Among them, DgpB-C complex was expressed in Escherichia coli, which cleaved the C-glycosidic bond in 1 but not puerarin. These results suggested that the puerarin C-deglycosylation reaction is a two-step enzymatic reaction, including the oxidation reaction at C-3″ in puerarin to give 1, and the subsequent C-deglycosylation of 1 to provide daidzein.

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Identification and functional expression of genes encoding flavonoid O‐ and C‐glycosidases in intestinal bacteria

Cited by 60 publications

References 44 publications

Bacterial species involved in the conversion of dietary flavonoids in the human gut

Bacterial species involved in the conversion of dietary flavonoids in the human gut

Chalcone Isomerase from Eubacterium ramulus Catalyzes the Ring Contraction of Flavanonols

Expression and Characterization of the Human Intestinal Bacterial Enzyme Which Cleaves the <i>C</i>-Glycosidic Bond in 3″-Oxo-puerarin

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