紫杉醇生物合成的研究

抗癌新药紫杉醇是具有萜类环状结构的天然次生代谢产物。研究紫杉醇的生物合成对于人为定向地提高合成效率以及克隆重组合成中的关键酶基因,进而提高紫杉醇的合成量,都是十分有意义的基础工作。本文以植物和微生物的次生代谢及其主要代谢途径为知识背景,介绍了紫杉烷类物质的基本结构及其结构骨架的分类情况,综述了近年来围绕紫杉醇二萜骨架和侧链基团的生物合成途径的研究进展,对合成中的影响因素进行了初步的讨论。     

紫杉醇生物合成途径及调控研究进展

本文综述了紫杉醇的生物合成途径、代谢调控及基因工程方面的研究进展,总结了代谢调控与基因工程方法提高红豆杉属植物细胞培养紫杉醇合成量的研究状况,并在探讨生物合成途径理论的基础上,对紫杉醇生物合成的限速步骤进行了阐述,指出解决侧链合成的根速步骤问题会显著提高紫杉醇的生物合成量。     

紫杉醇生物合成途径中相关酶的研究进展

抗癌新药紫杉醇是具有萜类环状结构的一种重要次生代谢产物 ,研究紫杉醇的生物合成对于通过基因工程手段提高紫杉醇的产量 ,解决目前资源紧缺造成的巨大供求矛盾具有重要意义 ,这就需要对紫杉醇生物合成途径中催化各步反应 (尤其是关键步骤 )的酶以及编码这些酶的基因有个全面的了解。对近年来紫杉醇生物合成途径中相关酶的研究进行了综述 ,大部分酶及相关基因已被分离、克隆 ,但还有一些酶及相关基因没有发现 ,有待继续深入研究。     

紫杉醇生物合成酶的研究进展

抗癌药紫杉醇是具有萜类环状结构的天然次生代谢产物.研究紫杉醇生物合成酶,特别是其合成关键酶,将为利用基因工程手段大量生产紫杉醇打下基础.对紫杉醇生物合成过程中参与酶的研究进展作一综述.     

紫杉醇生物合成相关酶类的研究进展

紫杉醇是红豆杉属植物次生代谢产物之一,是近20年来抗癌药物研究领域的重要发现。弄清楚紫杉醇合成途径和相关酶的反应可以从根本上大大提高紫杉醇的产量。综述近几年来紫杉醇生物合成途径中相关酶的研究工作,包括已经得到相应cDNA克隆的紫杉二烯合成酶,细胞色素P450氧化酶和3个紫杉烷的乙酰转移酶,由于GGPP是紫杉醇合成的必需前体,HMGR和GGPP合成酶的相关情况也有简述。     

诱导子对红豆杉培养细胞紫杉醇产量的影响

利用红豆杉细胞培养技术生产紫杉醇是目前紫杉醇生产的研究热点之一,并已取得了较大进展,其中如何提高紫杉醇的产量是研究的关键。目前通过促进紫杉醇代谢来提高产量最常用、最重要的方法之一是添加诱导子。这是来源于病原微生物的一类化学物质,具有诱导植物细胞中防卫基因表达诱发植物过敏反应和促进植物细胞中特定次生代谢产物的合成等多种功能。就近年来在红豆杉细胞培养生产紫杉醇方面的研究进展进行简要论述,着重介绍了添加诱导子在促进紫杉醇生物合成中的应用。     

诱导子在红豆杉细胞培养生产紫杉醇中的应用研究进展

诱导子作为一种调控植物次生代谢产物生物合成的重要手段,用于红豆杉(Taxus)细胞培养生产紫杉醇的研究效果显著。本文分别就生物诱导子和非生物诱导子促进紫杉醇生物合成及其可能的作用机制进行了综述。     

bZIP转录因子调控植物次生代谢产物生物合成的研究进展

植物次生代谢产物是通过次生代谢产生的一类小分子有机化合物,是植物适应环境的表现,次生代谢产物也是重要药物和化工原料的来源。bZIP转录因子是普遍存在于真核生物中的一类多基因家族,可有效调控植物次生代谢产物的生物合成。本文概述了植物bZIP转录因子的结构和类型,重点阐述了bZIP转录因子调控萜类、黄酮类和生物碱等植物次生代谢产物生物合成的研究进展,并对研究前景进行了展望。深入探讨bZIP转录因子的调控机制,有助于利用基因工程技术优化植物次生代谢途径,提高次生代谢产物的含量,在新药创制、工农业生产等方面具有广泛的应用前景。     

诱导子在红豆杉细胞培养生产紫杉醇中的应用研究进展

诱导子作为一种调控植物次生代谢产物生物合成的重要手段,用于红豆杉(Taxus)细胞培养生产紫杉醇的研究效果显著。本文分别就生物诱导子和非生物诱导子促进紫杉醇生物合成及其可能的作用机制进行了综述。     

基于定量PCR技术探讨紫杉醇生物合成的限速步骤

次生代谢产物牛物合成受到发育和诱导的调控,本实验研究了组织分化和诱导处理对紫杉醇生物合成的影响,并采用定量PCR技术分析了紫杉醇生物合成不同阶段关键酶基因的动态表达特征。结果表明。紫杉醇主要分布在中国红豆杉（Taxus chinensis）树皮和根皮组织中,针叶内含量很少,催化紫杉醇功能官能团连接的关键酶摹因也主要定位在树皮和根皮组织巾;茉莉酸甲酯（MJ）和真菌诱导子F5分别提高了中国红豆杉悬浮培养细胞HG-1紫杉醇得率8倍和10倍,同时有效诱导紫杉醇生物合成基因的表达。发现催化紫杉醇侧链连接的基因与紫杉醇生物合成早正相关。结果表明。紫杉醇生物合成的限速步骤是催化功能官能团连接的步骤。     

紫杉醇生物合成途径中羟化酶的研究进展

紫杉醇是一种从红豆杉植物中提取的具有显著抗癌效果的萜类化合物,但在红豆杉中含量很低,难以满足日益增长的临床需求。近年来,利用合成生物学技术建立新的紫杉醇来源途径已成为研究热点。目前,紫杉醇合成相关酶基因大部分已被克隆和鉴定,但其中羟化酶基因的发现与应用仍是目前研究的热点和难点。本文对紫杉醇生物合成途径研究进展进行了综述,对其中羟化酶的克隆及功能研究体系进行了重点深入分析,最后探讨了本领域未来的研究方向并对其前景进行展望,以期为紫杉醇合成途径中未知羟化步骤的羟化酶基因克隆,以及利用合成生物学技术实现紫杉醇的大量生产提供依据。     

Cell Apoptosis Induced by Oligosaccharide in Suspension Cultures of Taxus chinenesis

Taxol production of Taxus chinensis（Pilger） Rehd. var.mairei (Lemeeet Lévl.) Cheng et L. K. Fu induced by oligosaccharide from Fusarium oxysporum f.vasinfectum (Atkinson) Snyder et Hansen was studied in suspension cultures, and it was found that oligosaccharide triggered cell apoptosis. Under transmission electron microscope the following morphological changes were observed: cell shrinkage, condensation of cytoplasm, nuclear fragmentation, and the increase of high electron density bodies in vacuole in great quantity. In oligosaccharide treated cells, agarose gel electrophoresis revealed that DNA was digested into oligonucleosomal fragments that were times of 200 bp appearing as DNA ladders. Control cells were in normal physiological state, they were intact, abundant in organelle and with integral nucleus DNA, and the rate of taxol biosynthesis in these cells was very low. After the oligosaccharide to the culture system, the defense system of cells was elicited and the secondary metabolism was strengthened, i.e. phenolics were accumulated in the medium, the activity of polyphenol oxidase (PPO) was increased quickly and secondary wall of cells was thickened. The activity of L phenylalanine ammonia lyase (PAL), the critical enzyme of the phenylpropanoid pathway, was increased promptly 1 h after elicitation. The rate of taxol production was improved sharply and the maximal taxol concentration at 72 h was six times that of control. Appearance of cell apoptosis was accompanied with the highest concentration of taxol in suspension cultures.     

Transcript profiling of jasmonate‐elicited Taxus cells reveals a β‐phenylalanine‐CoA ligase

Plant cell cultures constitute eco‐friendly biotechnological platforms for the production of plant secondary metabolites with pharmacological activities, as well as a suitable system for extending our knowledge of secondary metabolism. Despite the high added value of taxol and the importance of taxanes as anticancer compounds, several aspects of their biosynthesis remain unknown. In this work, a genomewide expression analysis of jasmonate‐elicited Taxus baccata cell cultures by complementary DNA‐amplified fragment length polymorphism (cDNA‐AFLP) indicated a correlation between an extensive elicitor‐induced genetic reprogramming and increased taxane production in the targeted cultures. Subsequent in silico analysis allowed us to identify 15 genes with a jasmonate‐induced differential expression as putative candidates for genes encoding enzymes involved in five unknown steps of taxane biosynthesis. Among them, the TB768 gene showed a strong homology, including a very similar predicted 3D structure, with other genes previously reported to encode acyl‐CoA ligases, thus suggesting a role in the formation of the taxol lateral chain. Functional analysis confirmed that the TB768 gene encodes an acyl‐CoA ligase that localizes to the cytoplasm and is able to convert β‐phenylalanine, as well as coumaric acid, into their respective derivative CoA esters. β‐phenylalanyl‐CoA is attached to baccatin III in one of the last steps of the taxol biosynthetic pathway. The identification of this gene will contribute to the establishment of sustainable taxol production systems through metabolic engineering or synthetic biology approaches.     

紫杉醇生物合成的研究进展

本文对近年来研究紫杉醇的生物合成及生物合成途径中关键酶的进展进行了评述。目前紫杉醇的生物合成途径已经基本明了,其生物合成途径中环化酶的基因已经克隆成功。在分子及基因水平上大量生产紫杉醇的曙光已经出现。     

Genome and secretome analysis of jute endophyte Grammothele lineata strain SDL-CO-2015-1: Insights into its lignocellulolytic structure and secondary metabolite profile

Grammothele lineata strain SDL-CO-2015-1, jute (Corchorus olitorius) endophyte has been reported to produce anti-cancer drug paclitaxel in culture condition. Here we investigated the genome using different bioinformatic tools to find its association with the production of commercially important compounds including taxol. Carbohydrate-active enzymes, proteases, and secretory proteins were annotated revealing a complex endophytic relationship with its plant host. The presences of a diverse range of CAZymes including numerous lignocellulolytic enzymes support its potentiality in biomass degradation. Genome annotation led to the identification of 28 clusters for secondary metabolite biosynthesis. Several biosynthesis gene clusters were identified for terpene biosynthesis from antiSMASH analysis but none could be specifically pinned to taxol synthesis. This study will direct us to understand the genomic organization of endophytic basidiomycetes with a potential for producing numerous commercially important enzymes and secondary metabolites taking G. lineata as a model.