Strictosidine activation in Apocynaceae: towards a "nuclear time bomb"?
Strictosidine activation in Apocynaceae: towards a "nuclear time bomb"?
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DOI：
10.1186/1471-2229-10-182
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发表时间：
2010-08-19
影响因子：
5.3
通讯作者：
Burlat V
中科院分区：
文献类型：
--
作者：
Guirimand G;Courdavault V;Lanoue A;Mahroug S;Guihur A;Blanc N;Giglioli-Guivarc'h N;St-Pierre B;Burlat V
单萜烯吲哚生物碱生物合成途径的前两个酶促步骤是由将色胺和番木香精缩成的限制性内酯合成酶和β-D-葡萄糖苷酶催化合成的。生成的不稳定苷元迅速转化为高活性的二醛，从中衍生出2,000多个MIA。许多研究都是为了阐明长春花中长春花碱和长春新碱或萝芙蓉中的艾季马林等有药用价值的MIA的生物合成和调控。然而，有关MIA的生理功能的报道很少。在本研究中，我们证明了植物体内存在一个严格的糖苷池，并且严格的糖苷脱糖产物(S)专一地负责体外蛋白质的交联和沉淀，这表明在植物防御中，严格的糖苷的激活具有潜在的作用。这种激活过程的空间可行性在PLANTA中进行了评估。一方面，原位杂交研究表明，CrSTR和CrSGD在月季花气生器官的表皮第一屏障中共表达。然而，结合GFP成像、双分子荧光互补和电迁移率移位酶谱实验表明，玫瑰花冠和蛇纹夜蛾的STR都定位于液泡中，而这两种植物的SGD则以高度稳定的超分子聚集体的形式积累在细胞核内。缺失和融合研究使我们能够识别和展示CrSTR和CrSGD靶向序列的功能。绘制了一个空间模型来解释正常生理条件下STR和SGD的亚细胞隔离在控制MIA代谢流量中的作用。该模型还阐明了在潜在的草食动物取食过程中，在酶-底物重聚时，严格苷液泡池大量激活的可能机制，构成了所谓的“核定时炸弹”，指的是通常用于描述十字花科中黑芥子酶-硫代葡萄糖苷防御系统的“芥子油炸弹”。
The first two enzymatic steps of monoterpene indole alkaloid (MIA) biosynthetic pathway are catalysed by strictosidine synthase (STR) that condensates tryptamine and secologanin to form strictosidine and by strictosidine β-D-glucosidase (SGD) that subsequently hydrolyses the glucose moiety of strictosidine. The resulting unstable aglycon is rapidly converted into a highly reactive dialdehyde, from which more than 2,000 MIAs are derived. Many studies were conducted to elucidate the biosynthesis and regulation of pharmacologically valuable MIAs such as vinblastine and vincristine in Catharanthus roseus or ajmaline in Rauvolfia serpentina. However, very few reports focused on the MIA physiological functions. In this study we showed that a strictosidine pool existed in planta and that the strictosidine deglucosylation product(s) was (were) specifically responsible for in vitro protein cross-linking and precipitation suggesting a potential role for strictosidine activation in plant defence. The spatial feasibility of such an activation process was evaluated in planta. On the one hand, in situ hybridisation studies showed that CrSTR and CrSGD were coexpressed in the epidermal first barrier of C. roseus aerial organs. However, a combination of GFP-imaging, bimolecular fluorescence complementation and electromobility shift-zymogram experiments revealed that STR from both C. roseus and R. serpentina were localised to the vacuole whereas SGD from both species were shown to accumulate as highly stable supramolecular aggregates within the nucleus. Deletion and fusion studies allowed us to identify and to demonstrate the functionality of CrSTR and CrSGD targeting sequences. A spatial model was drawn to explain the role of the subcellular sequestration of STR and SGD to control the MIA metabolic flux under normal physiological conditions. The model also illustrates the possible mechanism of massive activation of the strictosidine vacuolar pool upon enzyme-substrate reunion occurring during potential herbivore feeding constituting a so-called "nuclear time bomb" in reference to the "mustard oil bomb" commonly used to describe the myrosinase-glucosinolate defence system in Brassicaceae.
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影响因子：
5.1
作者：
GUSMAYER, S;BRUNNER, H;RUDIGER, W
通讯作者：
RUDIGER, W
影响因子：
7.2
作者：
Burlat, V;Oudin, A;St-Pierre, B
通讯作者：
St-Pierre, B
影响因子：
7.7
作者：
Kissen, Ralph;Rossiter, John T.;Bones, Atle M.
通讯作者：
Bones, Atle M.
影响因子：
4.8
作者：
Kolaczkowski, M;vanderRest, M;Goffeau, A
通讯作者：
Goffeau, A
DOI：
10.1007/978-3-642-04670-4_8
发表时间：
2010-01-01
期刊：
PLANT DEVELOPMENTAL BIOLOGY: BIOTECHNOLOGICAL PERSPECTIVES VOL 2
影响因子：
--
作者：
Guirimand, G.;Courdavault, V.;Burlat, V.
通讯作者：
Burlat, V.