The biosynthetic pathway to abscisic acid via ionylideneethane in the fungus Botrytis cinerea
The biosynthetic pathway to abscisic acid via ionylideneethane in the fungus Botrytis cinerea
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DOI：
10.1016/j.phytochem.2004.08.025
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发表时间：
2004-10-01
期刊：
影响因子：
3.8
通讯作者：
Ohigashi, H
中科院分区：
文献类型：
--
作者：
Inomata, M;Hirai, N;Ohigashi, H
研究了灰葡萄孢真菌中异戊烯二磷酸合成脱落酸 (ABA) 的生物合成途径。 O-18(2) 和(H2O)-O-18 的标记实验表明ABA 的C1、-1、-1' 和-4' 处的所有氧原子均来自分子氧，而不是来自水。这一发现不仅与已知的通过类胡萝卜素氧化裂解的类胡萝卜素途径不一致，而且与通过法尼基二磷酸环化的经典直接途径不一致。该真菌产生了新的C-15化合物，2E,4E-α-亚碘基乙烷和2Z,4E-α-亚碘基乙烷，以及2E,4E,6E-别法呢烯和2Z,4E,6E-别法呢烯，但除了痕量的八氢番茄红素外，显然不产生类胡萝卜素。 C-13标记的C-15化合物被真菌转化为ABA，2Z,4E-α-亚离子乙烷的掺入率高于2E,4E-α-亚离子乙烷。从这些结果得出结论，法呢基二磷酸在C-1处被还原，在C-4处去饱和，并在C-2处异构化形成2Z,4E,6E-阿洛法呢烯，然后环化为2Z,4E-α-亚碘基乙烷；然后亚离子乙烷被分子氧氧化成ABA。这种通过亚基乙烷的直接途径意味着真菌 ABA 的生物合成途径（不仅在异戊烯基二磷酸之前而且在异戊烯基二磷酸之后）与植物中 ABA 的生物合成途径不同，因为植物 ABA 是使用非甲羟戊酸和类胡萝卜素途径生物合成的。 (C) 2004 Elsevier Ltd. 保留所有权利。
The biosynthetic pathway to abscisic acid (ABA) from isopentenyl diphosphate in the fungus, Botrytis cinerea, was investigated. Labeling experiments with O-18(2) and (H2O)-O-18 indicated that all oxygen atoms at C1, -1, -1' and -4' of ABA were derived from molecular oxygen, and not from water. This finding was inconsistent not only with the known carotenoid pathway via oxidative cleavage of carotenoids, but also with the classical direct pathway via cyclization of farnesyl diphosphate. The fungus produced new C-15-compounds, 2E,4E-alpha-ionylideneethane and 2Z,4E-alpha-ionylideneethane, along with 2E,4E,6E-allofarnesene and 2Z,4E,6E-allofarnesene, but did not apparently produce carotenoids except for a trace of phytoene. The C-15-compounds labeled with C-13 were converted to ABA by the fungus, and the incorporation ratio of 2Z,4E-alpha-ionylideneethane was higher than that of 2E,4E-alpha-ionylideneethane. From these results, it was concluded that farnesyl diphosphate was reduced at C-1, desaturated at C-4, and isomerized at C-2 to form 2Z,4E,6E-allofarnesene before being cyclized to 2Z,4E-alpha-ionylideneethane; the ionylideneethane was then oxidized to ABA with molecular oxygen. This direct pathway via ionylideneethane means that the biosynthetic pathway to fungal ABA, not only before but also after isopentenyl diphosphate, differs from that to ABA in plants, since plant ABA is biosynthesized using the non-mevalonate and carotenoid pathways. (C) 2004 Elsevier Ltd. All rights reserved.