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Deavours BE, Liu CJ, Naoumkina MA, Tang Y, Farag MA, Sumner LW, Noel JP, Dixon RA. Functional analysis of members of the isoflavone and isoflavanone O-methyltransferase enzyme families from the model legume Medicago truncatula. PLANT MOLECULAR BIOLOGY 2006; 62:715-33. [PMID: 17001495 PMCID: PMC2862459 DOI: 10.1007/s11103-006-9050-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 07/08/2006] [Indexed: 05/12/2023]
Abstract
Previous studies have identified two distinct O-methyltransferases (OMTs) implicated in isoflavonoid biosynthesis in Medicago species, a 7-OMT methylating the A-ring 7-hydroxyl of the isoflavone daidzein and a 4'-OMT methylating the B-ring 4'-hydroxyl of 2,7,4'-trihydroxyisoflavanone. Genes related to these OMTs from the model legume Medicago truncatula cluster as separate branches of the type I plant small molecule OMT family. To better understand the possible functions of these related OMTs in secondary metabolism in M. truncatula, seven of the OMTs were expressed in E. coli, purified, and their in vitro substrate preferences determined. Many of the enzymes display promiscuous activities, and some exhibit dual regio-specificity for the 4' and 7-hydroxyl moieties of the isoflavonoid nucleus. Protein structure homology modeling was used to help rationalize these catalytic activities. Transcripts encoding the different OMT genes exhibited differential tissue-specific and infection- or elicitor-induced expression, but not always in parallel with changes in expression of confirmed genes of the isoflavonoid pathway. The results are discussed in relation to the potential in vivo functions of these OMTs based on our current understanding of the phytochemistry of M. truncatula, and the difficulties associated with gene annotation in plant secondary metabolism.
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Affiliation(s)
- Bettina E. Deavours
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Chang-Jun Liu
- Howard Hughes Medical Institute, Jack Skirball Chemical Biology and Proteomics Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92036, USA
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Marina A. Naoumkina
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Yuhong Tang
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Mohamed A. Farag
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Lloyd W. Sumner
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Joseph P. Noel
- Howard Hughes Medical Institute, Jack Skirball Chemical Biology and Proteomics Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92036, USA
| | - Richard A. Dixon
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
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Kim JH, Shin KH, Ko JH, Ahn JH. Glucosylation of flavonols by Escherichia coli expressing glucosyltransferase from rice (Oryza sativa). J Biosci Bioeng 2006; 102:135-7. [PMID: 17027877 DOI: 10.1263/jbb.102.135] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 05/17/2006] [Indexed: 11/17/2022]
Abstract
A glucosyltransferase cDNA, RF5, was cloned from Oryza sativa using an RT-PCR strategy and expressed in Escherichia coli. Several flavonoids were tested for their ability to serve as substrates for RF5. RF5 effectively glucosylated kaempferol and quercetin to produce their 3-O-glucosides. Thus, RF5 could be defined as a flavonol 3-O-glucosyltransferase. E. coli cells expressing RF5 effectively converted 100 microM of kaempferol and quercetin into their corresponding glucosides.
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Affiliation(s)
- Ji Hye Kim
- Division of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701, Korea
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Hyung Ko J, Gyu Kim B, Joong-Hoon A. Glycosylation of flavonoids with a glycosyltransferase from Bacillus cereus. FEMS Microbiol Lett 2006; 258:263-8. [PMID: 16640583 DOI: 10.1111/j.1574-6968.2006.00226.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Microbial glycosyltransferases can convert many small lipophilic compounds such as phenolics, terpenoids, cyanohydrins and alkaloids into glycons using uridine-diphosphate-activated sugars. The main chemical functions of glycosylation processes are stabilization, detoxification and solubilization of the substrates. The gene encoding the UDP-glycosyltransferase from Bacillus cereus, BcGT-1, was cloned by PCR and sequenced. BcGT-1 was expressed in Escherichia coli BL21 (DE3) with a his-tag and purified using a His-tag affinity column. BcGT-1 could use apigenin, genistein, kaempferol, luteolin, naringenin and quercetin as substrates and gave two reaction products. The enzyme preferentially glycosylated at the 3-hydroxyl group, but it could transfer a glucose group onto the 7-hydroxyl group when the 3-hydroxyl group was not available. The reaction products made by biotransformation of flavonoids with E. coli expressing BcGT-1 are similar to those produced with the purified recombinant enzyme. Thus, this work provides a method that might be useful for the biosynthesis of flavonoid glucosides and for the glycosylation of related compounds.
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Affiliation(s)
- Jae Hyung Ko
- Division of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul, Korea
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Kim BG, Kim H, Hur HG, Lim Y, Ahn JH. Regioselectivity of 7-O-methyltransferase of poplar to flavones. J Biotechnol 2006; 126:241-7. [PMID: 16713650 DOI: 10.1016/j.jbiotec.2006.04.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2006] [Revised: 03/27/2006] [Accepted: 04/07/2006] [Indexed: 11/29/2022]
Abstract
POMT-7, an O-methyltransferase from poplar (Populus deltoids) was used to modify a variety of flavonoid compounds. POMT-7 was able to transfer a methyl group to several flavonoids containing a C-7 hydroxyl group. However, POMT-7 showed a higher affinity toward flavonol and flavone such as apigenin, kaempferol, luteolin, and quercetin than flavanone and isoflavone. Based on comparison of HPLC retention times with authentic compounds and corresponding nuclear magnetic resonance spectroscopy data, the methylation position of the reaction products was determined to be at the hydroxyl group of C-7. Biotransformation kinetics indicated that the enzyme converted more than 80% of the apigenin, kaempferol, luteolin and quercetin substrates, which were added at concentration of 70 microM, into corresponding 7-methoxy compounds within 24 h.
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Affiliation(s)
- Bong-Gyu Kim
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Republic of Korea
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Kim BG, Lee HJ, Park Y, Lim Y, Ahn JH. Characterization of an O-methyltransferase from soybean. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2006; 44:236-41. [PMID: 16777424 DOI: 10.1016/j.plaphy.2006.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Indexed: 05/10/2023]
Abstract
O-methyltransferases (OMTs) catalyze the transfer of a methyl group from S-adenosine-L-methionine to a hydroxyl group of an acceptor molecule to form methyl ether derivatives and can modify the basic backbone of a secondary metabolite. A new O-methyltransferase, SOMT-9, was cloned from Glycine max and found to encode a protein whose molecular weight is 27-kDa. SOMT-9 was expressed as a GST-fusion protein in Escherichia coli and several compounds such as caffeic acid, esculetin, narigenin, kaempferol, quercetin, and luteolin were tested as putative substrates of SOMT-9. HPLC and NMR results showed that SOMT-9 transfers a methyl group to the 3'-OH group of substrates having ortho-hydroxyl groups. SOMT-9 showed the highest affinity for quercetin, suggesting that SOMT-9 uses a flavonoid as a substrate. Based on its molecular weight and substrate specificity, SOMT-9 belongs to a new class of OMT and is likely to be involved in the biosynthesis of isorhamnetin.
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Affiliation(s)
- B G Kim
- Bio/Molecular Informatics Center, Division of Bioscience and Biotechnology, KonKuk University, Seoul 143-701, Korea
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Synthesis of Ermanin, 5,7-Dihydroxy-3,4'-dimethoxyflavone from Kaempferol, 3,5,7,4'-Tetrahydroxyflavone with Two O-Methyltransferases Expressed in E. coli. B KOREAN CHEM SOC 2006. [DOI: 10.5012/bkcs.2006.27.3.357] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Kim BG, Shin KH, Lee Y, Hur HG, Lim Y, Ahn JH. Multiple Regiospecific Methylations of a Flavonoid by Plant O-Methyltransferases Expressed in E. coli. Biotechnol Lett 2005; 27:1861-4. [PMID: 16328980 DOI: 10.1007/s10529-005-3893-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Accepted: 09/23/2005] [Indexed: 10/25/2022]
Abstract
Quercetin was methylated with two O-methyltransferases (OMTs) expressed in E. coli. A construct (RSOMT) was designed to express two OMTs: ROMT-9, which methylates specifically at the 3'-hydroxyl group of quercetin and SOMT-2, which methylates at the 4'-hydroxyl group. Both OMT genes were driven by T7 promoters and had ribosome binding sites. Both ROMT-9 and SOMT-2 were successfully expressed in E. coli transformant harboring RSOMT. Reaction products of quercetin with E. coli transformant containing RSOMT showed two methylation products that corresponded to the 3'-methylated and the 3',4'-dimethylated quercetin, which were confirmed by NMR. More than 90% of quercetin was converted into the 3',4'-dimethylated quercetin after 24 h incubation with E. coli transformant harboring RSOMT.
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Affiliation(s)
- Bong Gyu Kim
- Bio/Molecular Informatics Center, Department of Molecular Biotechnology, Konkuk University, 143-701, Seoul, Korea
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