Peroxisomal Localization of Arabidopsis Isopentenyl Diphosphate Isomerases Suggests That Part of the Plant Isoprenoid Mevalonic Acid Pathway Is Compartmentalized to Peroxisomes
Peroxisomal Localization of Arabidopsis Isopentenyl Diphosphate Isomerases Suggests That Part of the Plant Isoprenoid Mevalonic Acid Pathway Is Compartmentalized to Peroxisomes
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DOI：
10.1104/pp.108.127951
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发表时间：
2008-11-01
期刊：
影响因子：
7.4
通讯作者：
Eyal, Yoram
中科院分区：
文献类型：
--
作者：
Sapir-Mir, Maya;Mett, Anahit;Eyal, Yoram
类异二烯是最大的天然产物家族，在植物的基本过程中发挥着许多重要作用，包括光合作用、生长发育、繁殖、植物防御和对环境条件的适应（Gershenzon和Kreis, 1999； Rodriguez-Concepcion和Boronat， 2002）。所有类异戊二烯都是通过五碳通用类异戊二烯前体二磷酸异戊烯基（IPP）及其烯丙基异构体二磷酸二甲基烯丙基（DMAPP； McGarvey和Croteau， 1995）的缩合合成的。在高等植物中，IPP和DMAPP的生物合成有两个独立的通路，位于不同的细胞内区室中（见图1中植物类异戊二烯通路区室化的当前模型）。在甲基戊酸（MVA）途径，也就是胞质途径中，IPP/DMAPP的生物合成始于乙酰辅酶a的缩合（Qureshi and Porter, 1981; Newman and Chappell, 1999），而在质体中，IPP/DMAPP由丙酮酸和甘油醛-3- p通过甲基红四醇磷酸（MEP；或非甲戊酸）途径形成（Lichtenthaler et al., 1997,1999; Eisenreich et al., 1998,2001; Rohmer, 1999）。最初的研究表明，IPP/DMAPP的mva途径衍生的池是法尼基二磷酸（FPP; C15）的前体，最终是倍半萜、三萜和甾醇，而IPP/DMAPP的mep途径衍生的可塑性池提供香叶基二磷酸（C10）、香叶基二磷酸（C20）的前体，最终是单萜、二萜和四萜。尽管MVA和MEP通路的亚细胞区隔使它们能够独立运作，但最近发现这两条通路之间存在代谢互导（Bick and Lange, 2003； Hemmerlin等人，2003；Laule等人，2003；Schuhr等人，2003；Dudareva等人，2005；Hampel等人，2005）。植物类异戊二烯生物合成途径的调节、通量的控制和中间体的通道是人们感兴趣的主要问题，但仍未得到很好的理解。MVA通路的通量似乎受到严格调节。主要来自哺乳动物系统，但也来自植物系统的数据表明，3-羟基-3-甲基戊二酰辅酶a还原酶（HMGR）是一种限速酶，在翻译后受到反馈抑制机制的调节（Chappell等人，1995；Gardner和Hampton， 1999）。对于植物来说，一个主要的谜团是MVA通路在两个分支之间的不同通道，一个分支通向倍半萜烯，另一个通向甾醇。一些证据支持这样一种观点，即FPP位于甾醇和倍半萜之间的分支点，主要用于每个细胞都需要的甾醇生物合成（Hartmann, 2003），而其用于倍半萜生物合成的可用性仅限于特定的生理条件（如病原体攻击）和/或特定的组织（如精油腺）。(1)在健康烟草（Nicotiana tabacum）植物和烟草来源的细胞培养中，倍半萜，包括植物恢复素辣椒醇，几乎无法检测到，但只有在暴露于病原体或诱导后才会产生显著水平（Chappell和Nable, 1987； Vogeli和Chappell， 1988）。(2)烟草中HMGR非调控形式（缺乏n端膜锚）的组成性过表达导致总甾醇水平增加3至10倍，但倍半萜水平没有增加（Chappell等，1995）。(3)柑橘价烯合成酶（Sharon-Asa et al., 2003）在转基因烟草中的组成性过表达并未导致…
Isoprenoids, the largest family of natural products, play numerous vital roles in basic plant processes, including photosynthesis, growth and development, reproduction, plant defense, and adaptation to environmental conditions (Gershenzon and Kreis, 1999; Rodriguez-Concepcion and Boronat, 2002). All isoprenoids are synthesized via the condensation of the fivecarbon universal isoprenoid precursors, isopentenyl diphosphate (IPP) and its allylic isomer dimethylallyl diphosphate (DMAPP; McGarvey and Croteau, 1995). In higher plants, two independent pathways located in separate intracellular compartments are involved in the biosynthesis of IPP and DMAPP (see current model for plant isoprenoid pathways compartmentalization in Fig. 1). In the mevalonic acid (MVA) pathway, which is referred to as the cytosolic pathway, biosynthesis of IPP/DMAPP starts from the condensation of acetyl-CoA (Qureshi and Porter, 1981; Newman and Chappell, 1999), whereas in plastids, IPP/DMAPP are formed from pyruvate and glyceraldehyde-3-P via the methylerythritol phosphate (MEP; or non-mevalonate) pathway (Lichtenthaler et al., 1997, 1999; Eisenreich et al., 1998, 2001; Rohmer, 1999). Initial research indicated that the MVA-pathway-derived pool of IPP/DMAPP serves as a precursor of farnesyl diphosphate (FPP; C15) and, ultimately, the sesquiterpenes, triterpenes, and sterols, whereas the plastidic MEP-pathwayderived pool of IPP/DMAPP provides the precursors of geranyl diphosphate (C10), geranylgeranyl diphosphate (C20), and, ultimately, the monoterpenes, diterpenes, and tetraterpenes. Although the subcellular compartmentalization of MVA and MEP pathways allows them to operate independently, metabolic cross talk between these two pathways was recently implied (Bick and Lange, 2003; Hemmerlin et al., 2003; Laule et al., 2003; Schuhr et al., 2003; Dudareva et al., 2005; Hampel et al., 2005).Regulation of plant isoprenoid biosynthetic pathways, the control of flux, and the channeling of intermediates are issues of major interest but still not well understood. Flux of the MVA pathway appears to be tightly regulated. Data obtained mainly from mammalian systems, but also from plant systems, suggest that 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) is a rate-limiting enzyme, which is posttranslationally regulated by feedback-inhibition mechanisms (Chappell et al., 1995; Gardner and Hampton, 1999). A major enigma, specific for plants, concerns the differential channeling of the MVA pathway flux between the two pathway branches, one leading to sesquiterpenes and the other to sterols. Several bodies of evidence support the notion that FPP, which is positioned at the branch point between sterol and sesquiterpenes, is available mainly for sterol biosynthesis (Hartmann, 2003), which is required in every cell, while its availability for sesquiterpene biosynthesis is limited to specific physiological conditions (ie pathogen attack) and/or to specific tissues (ie essential oil glands).(1) In healthy tobacco (Nicotiana tabacum) plants and tobacco-derived cell culture, sesquiterpenes, including the phytoalexin capsidiol, are almost undetectable, but are produced to significant levels only following exposure to pathogens or elicitation (Chappell and Nable, 1987; Vogeli and Chappell, 1988).(2) Constitutive overexpression in tobacco of a nonregulated form of HMGR (lacking the N-terminal membrane anchor) resulted in a 3-to 10-fold increase in total sterol levels but no increase in sesquiterpene levels (Chappell et al., 1995).(3) Constitutive overexpression of citrus valencene synthase (Sharon-Asa et al., 2003) in transgenic tobacco did not result in synthesis of …