摘要
萜类物质是广泛分布于生物界的一类天然产物,也是重要生命物质。萜类物质通过甲羟戊酸(MVA)途径和2-C-甲基-D-赤藻糖醇-4-磷酸(MEP)途径合成,古细菌、真菌和动物及人的萜类物质主要通过MVA途径合成,而多数真细菌(即通常而言的细菌)则利用MEP途径。植物同时拥有两种途径但分别定位于细胞质和质体。1-脱氧木酮糖-5-磷酸合成酶(DXS)是MEP途径的第一个酶,也是该途径的关键调控位点。现从DXS在MEP途径中的作用、DXS结构、亚细胞定位和酶活性、编码基因及突变体等方面对DXS进行全面阐述。拟南芥DXS基因插入突变体cla1-1发生白化,DXS基因表达与类胡萝卜素等萜类物质积累密切相关,在转基因生物体中过度表达DXS可促进萜类物质合成。植物DXS具有典型的质体转运肽序列,决定了DXS的质体定位。完备的DXS活性分析体系为DXS抑制剂开发筛选等研究奠定良好基础。DXS由一至多个基因编码,随生物种类而异,根据同源性,植物DXS基因可分成两类。DXS基因家族不同成员具有不同的表达模式,但通常有一个成员在多种组织中广泛表达。
Terpenoids, also known as isoprenoids, are a class of natural products widely present in various organisms and play key roles in life. Terpenoids are biosynthesized from mevalonate （MVA） or 2-C-methyl-D- erythritol 4-phosphate （MEP） pathway, as found in archaebacteria, fungi, animals and human for the former path- way and in most eubacteria, commonly referred as bacteria, for the latter one. Both pathways exist in plants but locate in cytosol and plastids, respectively. 1-deoxy-D-xylulose 5-phosphate synthase （DXS） is the first and key regulatory enzyme for MEP pathway. The importance of DXS in MEP pathway as well as structure, sub-cellular localization, enzyme activity analysis of DXS protein and DXS genes and mutants were reviewed. Arabidopsis T- DNA mutant clal-1 with disrupted DXS displays albino phenotype. Accumulation of terpenoids including caro- tenoids was well correlated with DXS mRNA abundance, and the accumulation can be promoted by overexpressing DXS in transgenic organisms. Typical plastid transit peptide sequence, responsible for plastid localization of the protein, was observed in plant DXS. Various techniques were established for enzyme activity analysis of DXS, which contribute to development and screening of DXS inhibitors. DXS was encoded by a single gene or a small gene family, variable among species. Plant DXS can be sorted into two classes based on homology analysis of protein sequences. Differential expression patterns were observed for DXS members, and generally one of them were widely expressed in various tissues.
出处
《细胞生物学杂志》
CSCD
2007年第5期706-712,共7页
Chinese Journal of Cell Biology
基金
国家自然科学基金(No.30671449)
浙江省科技厅农业重点项目(No.2005C22059)~~
