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LOCALIZATION OF MEVALONATE PATHWAY AND NON-MEVALNATE PATHWAY

甲羟酸途径和非甲羟酸途径的定位

基本信息

批准号：
12660094
负责人：
NABETA Kensuke
金额：
$ 1.98万
依托单位：
OBIHIRO UNIVERSITY OF AGRICULTURE AND VETERINARY MEDICINE
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

The objectives of this research was to elucidate mechanism of the preferential labeling of the famesyl diphosphate (FPP)-derived portion in the formation of chloroplastidic terpenoids from MVA in cells of Bryophyta, and to confirm that this non-equivalent labeling has dose relation with localization of mevalonate (MVA) pathways hi cytosd and non-MVA pathway in plastids.Ubiquitous presence of non-equivalent labeling was observed in cultured cells of hornwort Anthoceros punctatus and liverwort, Ptychanthus striatus in the formation of the phytyl side-chain of chlorophyll a of the liverwort from MVA. The simultaneous involvement of MVA and deoxyxylulose (DXP) pathways for the phytyl side-chain biosynthesis was proven by incorporation study using ^2H and ^<13>C-labeled MVA and glucose. Uptake of isoprenyl diphosphates into liverwort chloroplasts was investigated by incorporation of radioactive precursors. The results obtained from these studies were summarized as follows.The incorporation of isoprenyl diphosphates using the intact chloroplasts from H. planus and P. striaaatus revealed that the chloroplast envelope of liverworts is highly permeable to FPP, while much less to IPP. In addition, as the chain length of the isoprenyl diphosphate increases, the radioactivity incorporated to the GGOH was also increased. Thus the non-equivalent labeling of the phytyl side-chain in liverworts has been possibly caused by selective incorporation of FPP into the chloroplasts, which is biosynthesized from MVA in cytosol, and its further condensation with endogenous IPP to form GGPP.Thus this study provides evidence for a rational explanation of possible mechanism for the preferential labeling in the FPP-derived portion of the phytyl side-chain of chlorophyll a in cultured cells of liverworts.

本研究的目的是阐明在苔藓细胞中MVA形成叶绿体萜类化合物过程中FPP衍生部分的优先标记机制，并证实这种非等价标记与MVA途径在胞质中的定位和非MVA途径在质体中的定位有关。用^2H和^&lt；13&gt；C标记的MVA和葡萄糖的掺入研究证实了MVA和脱氧果糖(DXP)途径同时参与植基侧链的生物合成。通过掺入放射性前体，研究了异戊二烯基二磷酸盐在地钱叶绿体中的吸收。这些研究的结果总结如下：利用完整的扁平苔叶绿体和条斑苔叶绿体掺入异戊二烯基二磷酸盐表明，苔类植物的叶绿体被膜对FPP具有很高的通透性，而对IPP的透性要小得多。此外，随着异戊二烯基二磷酸链长的增加，GGOH的放射性也随之增加。因此，苔类植物植基侧链的非等价性标记可能是由于FPP选择性地掺入叶绿体中，并进一步与内源IPP缩合形成GGP所致。因此，本研究为合理解释培养细胞中叶绿素a植基侧链的FPP优先标记的可能机制提供了证据。