Licorice beta-amyrin 11-oxidase, a cytochrome P450 with a key role in the biosynthesis of the triterpene sweetener glycyrrhizin.
Glycyrrhizin, a major bioactive compound derived from the underground parts of Glycyrrhiza (licorice) plants, is a triterpene saponin that possesses a wide range of pharmacological properties and is used worldwide as a natural sweetener. Because of its economic value, the biosynthesis of glycyrrhizin has received considerable attention. Glycyrrhizin is most likely derived from the triterpene beta-amyrin, an initial product of the cyclization of 2,3-oxidosqualene. The subsequent steps in glycyrrhizin biosynthesis are believed to involve a series of oxidative reactions at the C-11 and C-30 positions, followed by glycosyl transfers to the C-3 hydroxyl group; however, no genes encoding relevant oxidases or glycosyltransferases have been identified. Here we report the successful identification of CYP88D6, a cytochrome P450 monooxygenase (P450) gene, as a glycyrrhizin-biosynthetic gene, by transcript profiling-based selection from a collection of licorice expressed sequence tags (ESTs). CYP88D6 was characterized by in vitro enzymatic activity assays and shown to catalyze the sequential two-step oxidation of beta-amyrin at C-11 to produce 11-oxo-beta-amyrin, a possible biosynthetic intermediate between beta-amyrin and glycyrrhizin. CYP88D6 coexpressed with beta-amyrin synthase in yeast also catalyzed in vivo oxidation of beta-amyrin to 11-oxo-beta-amyrin. CYP88D6 expression was detected in the roots and stolons by RT-PCR; however, no amplification was observed in the leaves or stems, which is consistent with the accumulation pattern of glycyrrhizin in planta. These results suggest a role for CYP88D6 as a beta-amyrin 11-oxidase in the glycyrrhizin pathway.
Seki
Hikaru
H
Kihara Institute for Biological Research, Yokohama City University, Maioka-cho 641-12, Totsuka-ku, Yokohama, Kanagawa 244-0813, Japan.
Ohyama
Kiyoshi
K
Sawai
Satoru
S
Mizutani
Masaharu
M
Ohnishi
Toshiyuki
T
Sudo
Hiroshi
H
Akashi
Tomoyoshi
T
Aoki
Toshio
T
Saito
Kazuki
K
Muranaka
Toshiya
T
D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006035:Glycyrrhiza / Q000201:enzymology / Q000235:genetics; D019695:Glycyrrhizic Acid / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013549:Sweetening Agents / Q000737:chemistry / Q000378:metabolism*
D013549:Sweetening Agents; D019695:Glycyrrhizic Acid; D003577:Cytochrome P-450 Enzyme System
Biol Pharm Bull. 2001 Aug;24(8):912-6
11510484
Antiviral Res. 1988 Dec 11;10(6):289-98
3250333
J Hepatol. 1994 Oct;21(4):601-9
7814808
Proc Natl Acad Sci U S A. 2001 Feb 13;98(4):1501-6
11171980
Aliment Pharmacol Ther. 1998 Mar;12(3):199-205
9570253
Phytother Res. 2008 Feb;22(2):141-8
17886224
Lloydia. 1978 Jul-Aug;41(4):348-54
353426
Antiviral Res. 1987 Mar;7(3):127-37
3475037
FEBS J. 2006 Mar;273(5):948-59
16478469
Yakugaku Zasshi. 2000 Oct;120(10):849-62
11082698
FEBS Lett. 2006 Feb 20;580(5):1411-6
16458889
Drug Metabol Drug Interact. 1995;12(3-4):189-206
8820852
Plant Physiol. 1999 Feb;119(2):507-10
9952446
Plant Cell Rep. 1990 May;8(12):718-21
24232925
Plant Physiol. 1998 Jan;116(1):357-67
9449848
Plant Physiol. 2004 Jun;135(2):756-72
15208422
Methods Enzymol. 1996;272:51-64
8791762
Chem Pharm Bull (Tokyo). 2007 Oct;55(10):1518-21
17917299
Proc Natl Acad Sci U S A. 1998 Jul 21;95(15):9019-24
9671797
Biol Pharm Bull. 2001 Dec;24(12):1395-9
11767109
Plant Cell. 1995 Aug;7(8):1307-17
7549486
Proc Natl Acad Sci U S A. 2001 Nov 20;98(24):13595-600
11707604
FEBS J. 2008 Apr;275(8):1852-9
18336574
Plant Physiol. 2003 Jan;131(1):335-44
12529541
Lancet. 2003 Jun 14;361(9374):2045-6
12814717
Proc Natl Acad Sci U S A. 2001 Feb 13;98(4):2065-70
11172076
Plant Cell Rep. 1988 Dec;7(7):508-11
24240403
Plant Cell. 2006 Nov;18(11):3275-88
17138693
Nature. 2006 Apr 13;440(7086):940-3
16612385
Nucleic Acids Res. 1994 Nov 11;22(22):4673-80
7984417
Arch Pharm Res. 2004 Jan;27(1):57-60
14969340
Int Immunopharmacol. 2004 Dec 15;4(13):1633-44
15454116
Biol Pharm Bull. 1999 Sep;22(9):947-50
10513618