Transgene

转基因
  • 文章类型: Journal Article
    植物通过光合作用将太阳能和二氧化碳转化为有机化合物。蔗糖是光合作用过程中产生的主要碳酸盐。蔗糖磷酸合成酶(SPS)是控制植物蔗糖生物合成的关键酶。高等植物中至少有三个SPS基因家族,名为A,B,C.然而,在禾本科单子叶植物中,至少有5个SPS基因家族,名为A,B,C,DIII,和DIV。不同植物中的每个SPS基因家族都表现出不同的表达模式。因此SPS基因的不同家族参与了不同的生物学功能,包括蔗糖积累,植物生长和生产,和非生物胁迫耐受性。植物中的SPS活性受外源因子通过基因表达和可逆蛋白磷酸化调控。通过SPS基因转化来改善作物性状是一条切实可行的途径。这项工作分析了克隆,系统发育,植物SPS基因的调控机制,回顾了其生物学功能及其在作物改良中的作用,并讨论了挑战和未来前景。本文可为植物SPS基因的进一步研究和作物改良提供参考。
    Plants convert solar energy and carbon dioxide into organic compounds through photosynthesis. Sucrose is the primary carbonate produced during photosynthesis. Sucrose phosphate synthase (SPS) is the key enzyme controlling sucrose biosynthesis in plants. There are at least three SPS gene families in higher plants, named A, B, and C. However, in monocotyledonous plants from Poaceae, there are at least five SPS gene families, named A, B, C, DIII, and DIV. Each family of SPS genes in different plants shows a divergent expression pattern. So different families of SPS genes participate in diverse biological functions, including sucrose accumulation, plant growth and production, and abiotic stress tolerance. SPS activity in plants is regulated by exogenous factors through gene expression and reversible protein phosphorylation. It is a practicable way to improve crop traits through SPS gene transformation. This work analyzes the cloning, phylogeny, and regulatory mechanism of the SPS gene in plants, reviews its biological function as well as its role in crop improvement, and discusses the challenges and future perspectives. This paper can serve as a reference for further study on plant SPS genes and eventually for crop improvement.
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  • 文章类型: Journal Article
    当几丁质酶感染宿主昆虫时,它在昆虫病原真菌(EPF)的毒力中起着至关重要的作用。我们使用基因重组技术表达了三株Lecanicilliumlecanii的几丁质酶:Vl6063,V3450和Vp28。将ChitVl6063、ChitV3450和ChitVp28的ORF插入到含有强启动子和终止子的真菌表达载体pBARGPE-1中,分别,构建几丁质酶过表达质粒,然后用芽孢子转化法转化野生型菌株。通过ChitVl6063,ChitV3450和ChitVp28的过量生产,三个重组菌株对弓形虫的毒力得到了改善,显着降低了3.43%,1.72%,和1.23%的致命剂量,分别,根据昆虫生物测定法。同样,重组体(ChitVl6063,ChitV3450和ChitVp28)的致死时间也减少了29.51%,30.46%和33.90%,分别,与野生型菌株相比。提高几丁质酶的表达被认为是提高EPF值的有效方法。使用重组技术可以提高疗效,这为未来的杀虫应用提供了展望。
    Chitinase plays a vital role in the virulence of entomopathogenic fungi (EPF) when it infects host insects. We used gene recombination technology to express chitinase of three strains of Lecanicillium lecanii: Vl6063, V3450, and Vp28. The ORF of ChitVl6063, ChitV3450 and ChitVp28 were inserted into the fungal expression vector pBARGPE-1, which contained strong promoter and terminator, respectively, to construct a chitinase overpressing plasmid, then transformed the wild-type strain with blastospore transformation method. The virulence of the three recombinant strains against Toxoptera aurantii was improved by overproduction of ChitVl6063, ChitV3450, and ChitVp28, as demonstrated by significantly lower 3.43 %, 1.72 %, and 1.23 % fatal doses, respectively, according to an insect bioassay. Similarly, lethal times of recombinants (ChitVl6063, ChitV3450 and ChitVp28) were also decreased up to 29.51 %, 30.46 % and 33.90 %, respectively, compared to the wild-type strains. Improving the expression of chitinase is considered as an effective method for the enhancement of the EPF value. The efficacy could be enhanced using recombinant technology, which provides a prospecting view for future insecticidal applications.
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  • 文章类型: Journal Article
    WRKY基因家族广泛分布于植物中,在应激反应中发挥关键作用。然而,棉花中WRKY基因的结构组织和进化动力学尚未完全阐明。在这项研究中,在植物园棉中总共鉴定出112、119、217和222个WRKY基因,灵蒙地棉,陆地棉,和巴巴多斯棉属,分别。这670个WRKY基因被分为七个不同的亚组,并且在染色体上分布不均。保守图案的检查,域,顺式作用元素,和基因结构共同强调了棉花中WRKY基因家族的进化保守性和分歧性。同质性和共线性的分析进一步证实了扩张的实例,重复,和棉花进化过程中WRKY基因之间的丢失事件。此外,GhWRKY31转基因拟南芥在干旱和盐胁迫下表现出更高的发芽率和更长的根长。在棉花中沉默GhWRKY31导致ABA水平降低,脯氨酸,POD,和SOD,随着应激反应基因表达下调。酵母单杂交和分子对接试验证实了GhWRKY31与GhABF1、GhDREB2和GhRD29的W盒的结合能力。这些发现共同提供了对棉花WRKYs进化模式的系统和全面的见解,提出了一个合适的调控框架,用于开发具有增强的抗旱性和盐分胁迫能力的棉花品种。
    The WRKY gene family is ubiquitously distributed in plants, serving crucial functions in stress responses. Nevertheless, the structural organization and evolutionary dynamics of WRKY genes in cotton have not been fully elucidated. In this study, a total of 112, 119, 217, and 222 WRKY genes were identified in Gossypium arboreum, Gossypium raimondii, Gossypium hirsutum, and Gossypium barbadense, respectively. These 670 WRKY genes were categorized into seven distinct subgroups and unequally distributed across chromosomes. Examination of conserved motifs, domains, cis-acting elements, and gene architecture collectively highlighted the evolutionary conservation and divergence within the WRKY gene family in cotton. Analysis of synteny and collinearity further confirmed instances of expansion, duplication, and loss events among WRKY genes during cotton evolution. Furthermore, GhWRKY31 transgenic Arabidopsis exhibited heightened germination rates and longer root lengths under drought and salt stress. Silencing GhWRKY31 in cotton led to reduced levels of ABA, proline, POD, and SOD, along with downregulated expression of stress-responsive genes. Yeast one-hybrid and molecular docking assays confirmed the binding capacity of GhWRKY31 to the W box of GhABF1, GhDREB2, and GhRD29. The findings collectively offer a systematic and comprehensive insight into the evolutionary patterns of cotton WRKYs, proposing a suitable regulatory framework for developing cotton cultivars with enhanced resilience to drought and salinity stress.
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  • 文章类型: Journal Article
    与雄性相比,雌性柳树表现出更高的耐旱性,并且从外源乙酸(AA)改善的耐旱性中受益更多。然而,驱动这些性别特异性反应的潜在机制仍不清楚.为了全面研究柳树对干旱和外源AA的性二态反应机制,在这里,我们进行了生理表演,蛋白质组学,Lys-乙酰蛋白质组,以及暴露于干旱和AA干旱处理的雌性和雄性桃柳的转基因分析,关注蛋白质丰度和赖氨酸乙酰化(LysAc)的变化。耐旱雌性受干旱诱导的光合和氧化损伤较少,没有激活AA和乙酰辅酶A的生物合成,TCA循环,脂肪酸代谢,茉莉酸和干旱敏感男性一样强烈。外源性AA导致内源性AA的过度积累,并抑制了雄性中乙酰辅酶A的生物合成和利用。然而,外源AA大大提高了乙酰辅酶A的生物合成和利用,进一步增强了雌性的干旱性能,可能确定AA对女性的耐旱性比对男性的耐旱性有更大的改善。有趣的是,过表达乙酰辅酶A合成酶(ACS)可以重新编程脂肪酸,增加LysAc水平,提高耐旱性,强调ACS衍生的乙酰辅酶A参与干旱反应。此外,干旱和外源AA诱导的与组蛋白相关的性二态LysAc,转录因子,和柳树中的代谢酶。尤其是,外源AA可以通过降低LysAc水平和增加光合蛋白的丰度来大大提高品红的光合能力。而糖酵解中的高乙酰化,TCA循环,和脂肪酸生物合成可能作为负反馈,以适应干旱胁迫的雄性和应用AA的雌性的乙酰辅酶A生物合成和利用。因此,乙酰辅酶A的生物合成和利用决定了桃金娘对干旱和外源AA的性二态反应。
    Female willows exhibit greater drought tolerance and benefit more from exogenous acetic acid (AA)-improved drought tolerance than males. However, the potential mechanisms driving these sex-specific responses remain unclear. To comprehensively investigate the sexually dimorphic responsive mechanisms of willows to drought and exogenous AA, here, we performed physiological, proteomic, Lys-acetylproteomic, and transgenic analyses in female and male Salix myrtillacea exposed to drought and AA-applicated drought treatments, focusing on protein abundance and lysine acetylation (LysAc) changes. Drought-tolerant females suffered less drought-induced photosynthetic and oxidative damage, did not activate AA and acetyl-CoA biosynthesis, TCA cycle, fatty acid metabolism, and jasmonic acid signaling as strongly as drought-sensitive males. Exogenous AA caused overaccumulation of endogenous AA and inhibition of acetyl-CoA biosynthesis and utilization in males. However, exogenous AA greatly enhanced acetyl-CoA biosynthesis and utilization and further enhanced drought performance of females, possibly determining that AA improved drought tolerance more in females than in males. Interestingly, overexpression of acetyl-CoA synthetase (ACS) could reprogram fatty acids, increase LysAc levels, and improve drought tolerance, highlighting the involvement of ACS-derived acetyl-CoA in drought responses. In addition, drought and exogenous AA induced sexually dimorphic LysAc associated with histones, transcription factors, and metabolic enzymes in willows. Especially, exogenous AA may greatly improve the photosynthetic capacity of S. myrtillacea males by decreasing LysAc levels and increasing the abundances of photosynthetic proteins. While hyperacetylation in glycolysis, TCA cycle, and fatty acid biosynthesis potentially possibly serve as negative feedback to acclimate acetyl-CoA biosynthesis and utilization in drought-stressed males and AA-applicated females. Thus, acetyl-CoA biosynthesis and utilization determine the sexually dimorphic responses of S. myrtillacea to drought and exogenous AA.
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  • 文章类型: Journal Article
    豆素A是一种种子贮藏蛋白,为种子萌发提供营养。本研究的目的是描述杜仲中EuLEGA基因的结构和表达模式(E.ulmoides)并推断其功能作用。EuLEGA基因的EuLEGACDS的1287bp编码序列,编码含有428个氨基酸残基的蛋白质,被克隆。该结构预测该蛋白质属于RmlC(脱氧胸苷二磷酸,dTDP)-4-脱水甘露糖3,5-差向异构酶)样cupin保守结构域家族,其中包含两个RmlC,构建了EuLEGA基因的过表达(OE)载体,并将其遗传转化到烟草和E.ulmoides中;构建了EuLEGA基因的RNA干扰(RNAi)载体,并将其遗传转化到E.结果表明,EuLEGA基因能显著提高转基因烟草叶片和转基因杜松子菜再生芽中豆腐素A的含量,并且该基因在E.ulmoides中的OE可以促进鼠李糖含量的增加。RNAi导致E.ulmoides再生芽中豆球蛋白A含量显着降低。这是转基因烟草种子中豆球蛋白A的显着增加,这些结果表明,EuLEGA基因的表达与豆类A的积累密切相关。亚细胞定位研究表明,EuLEGA定位于液泡膜的细胞质中。对EuLEGA基因表达数据的分析显示,EuLEGA基因在萨马拉中的表达水平显着高于在叶和茎中的表达水平。此外,该研究还表明GA3可以上调EuLEGA基因的表达水平,而ABA和MeJA可以下调其表达水平。
    Legumin A is a seed storage protein that provides nutrients for seed germination. The purpose of this study was to describe the structure and expression pattern of the EuLEGA gene in Eucommia ulmoides Oliver (E. ulmoides) and to infer its functional role. The 1287 bp coding sequence of the EuLEGA CDS of the EuLEGA gene, encoding a protein containing 428 amino acid residues, was cloned. The structure predicted that the protein belonged to the RmlC (deoxythymidine diphosphates, dTDP)-4-dehydrorhamnose 3,5-epimerase)-like cupin conserved domain family, which contains both RmlC, a key enzyme for the synthesis of rhamnose and legumin A. The overexpression (OE) vector of the EuLEGA gene was constructed and genetically transformed into tobacco and E. ulmoides; the RNA interference (RNAi) vector of the EuLEGA gene was constructed and genetically transformed into E. ulmoides; and the contents of legumin A and rhamnose were detected. The results showed that the EuLEGA gene could significantly increase the content of legumin A in transgenic tobacco leaves and transgenic E. ulmoides regenerative buds, and the OE of this gene in E. ulmoides could promote an increase in rhamnose content. RNAi caused a significant decrease in the legumin A content in the regenerated buds of E. ulmoides. These was a significant increase in legumin A in the transgenic tobacco seeds, and these results indicate that the expression of the EuLEGA gene is closely related to the accumulation of legumin A. Subcellular localization studies revealed that EuLEGA is localized to the cytoplasm with the vacuolar membrane. Analysis of the EuLEGA gene expression data revealed that the expression level of the EuLEGA gene in the samaras was significantly greater than that in the leaves and stems. In addition, the study also demonstrated that GA3 can upregulate the expression levels of the EuLEGA gene, while ABA and MeJA can downregulate its expression levels.
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  • 文章类型: Journal Article
    小鼠腺病毒(MAdV)在研究宿主-腺病毒相互作用中起着重要作用。然而,MAdV仍然缺乏易于使用的反向遗传学系统。通过Gibson组装将野生型MAdV-1的基因组DNA与含有质粒骨架的PCR产物连接,构建感染性质粒pKRMAV1。通过限制性消化从pKRMAV1上切下片段,并用于产生中间质粒pKMAV1-ER,其中包含E3,纤维,E4和MAdV-1的E1区。将CMV启动子控制的GFP表达盒插入pKMAV1-ER中pIX基因的下游,然后转移至pKRMAV1以产生腺病毒质粒pKMAV1-IXCG。在pKMAV1-IXCG的双BstZ17I位点之间通过限制性组装可以方便地进行转基因的置换,产生了一系列腺病毒质粒。在将线性化的腺病毒质粒转染至小鼠NIH/3T3细胞后拯救重组病毒。携带GFP或萤火虫荧光素酶基因的MAdV-1病毒在基因转导中表征,菌斑形成,并通过观察报告基因的表达在体外或体内复制。结果表明,具有复制能力的载体很好地呈现了野生型MAdV-1的相关特性。通过构建带有越来越大的外源片段的病毒,发现MAdV-1可以耐受高达3.3kb的插入。总的来说,建立了具有复制能力的MAdV-1载体系统,这简化了改变转基因或修饰E1,纤维的程序,E3或E4基因。
    Mouse adenoviruses (MAdV) play important roles in studying host-adenovirus interaction. However, easy-to-use reverse genetics systems are still lacking for MAdV. An infectious plasmid pKRMAV1 was constructed by ligating genomic DNA of wild-type MAdV-1 with a PCR product containing a plasmid backbone through Gibson assembly. A fragment was excised from pKRMAV1 by restriction digestion and used to generate intermediate plasmid pKMAV1-ER, which contained E3, fiber, E4, and E1 regions of MAdV-1. CMV promoter-controlled GFP expression cassette was inserted downstream of the pIX gene in pKMAV1-ER and then transferred to pKRMAV1 to generate adenoviral plasmid pKMAV1-IXCG. Replacement of transgene could be conveniently carried out between dual BstZ17I sites in pKMAV1-IXCG by restriction-assembly, and a series of adenoviral plasmids were generated. Recombinant viruses were rescued after transfecting linearized adenoviral plasmids to mouse NIH/3T3 cells. MAdV-1 viruses carrying GFP or firefly luciferase genes were characterized in gene transduction, plaque-forming, and replication in vitro or in vivo by observing the expression of reporter genes. The results indicated that replication-competent vectors presented relevant properties of wild-type MAdV-1 very well. By constructing viruses bearing exogenous fragments with increasing size, it was found that MAdV-1 could tolerate an insertion up to 3.3 kb. Collectively, a replication-competent MAdV-1 vector system was established, which simplified procedures for the change of transgene or modification of E1, fiber, E3, or E4 genes.
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  • 文章类型: Journal Article
    Most viruses and transposons serve as effective carriers for the introduction of foreign DNA up to 11 kb into vertebrate genomes. However, their activity markedly diminishes with payloads exceeding 11 kb. Expanding the payload capacity of transposons could facilitate more sophisticated cargo designs, improving the regulation of expression and minimizing mutagenic risks associated with molecular therapeutics, metabolic engineering, and transgenic animal production. In this study, we improved the Tol2 transposon by increasing protein expression levels using a translational enhancer ( QBI SP163, ST) and enhanced the nuclear targeting ability using the nuclear localization protein H2B (SHT). The modified Tol2 and ST transposon efficiently integrated large DNA cargos into human cell cultures (H1299), comparable to the well-established super PiggyBac system. Furthermore, mRNA from ST and SHT showed a significant increase in transgene delivery efficiency of large DNA payloads (8 kb, 14 kb, and 24 kb) into zebrafish ( Danio rerio). This study presents a modified Tol2 transposon as an enhanced nonviral vector for the delivery of large DNA payloads in transgenic applications.
    大多数病毒和转座子可将长达11 kb的外源DNA有效引入脊椎动物基因组,但递送超过11 kb的DNA片段时,其活性明显减弱。扩大转座子的有效载荷能力将能够容纳更大的DNA片段、增强调节基因表达的能力,并最大限度地减少分子治疗、代谢工程和转基因动物相关的突变风险。在该研究中,我们通过翻译增强子QBI SP163和核定位蛋白H2B提高蛋白表达水平和细胞核靶向能力,产生了改善的Tol2转座子,ST和SHT。Tol2和ST转座子能有效地将大片段DNA整合到H1299细胞中,其效果可与改善的super PiggyBac转座子系统相媲美。我们发现ST和SHT mRNA能显著提高斑马鱼中大DNA片段(~8 kb, ~14 kb, ~24 kb)的转基因效率。该研究介绍了优化的Tol2转座子可作为一种改进的非病毒载体,应用于递送大DNA片段的转基因实验。.
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  • 文章类型: Journal Article
    紧凑型CRISPR系统的开发促进了递送,但同时降低了基因编辑效率。从而限制了CRISPR系统的进一步利用。提高CRISPR系统的效率是一项艰巨的任务,对生物技术的发展具有重要意义。在我们的工作中,我们报道了一种可以在细胞内环境中稳定存在的合成双抗体系统,特异性抑制NF-κB和β-catenin的功能。这不仅通过抑制细胞内的先天免疫应答以增强基因编辑效率来提高CRISPR系统的转基因表达,而且还表现出显著的肿瘤抑制作用。基于CRISPR-CasΦ的特异性输出表达调控,我们构建了一个基于CRISPR的基因表达平台,其中包括用于检测细胞内β-catenin和NF-κB的传感器模块,以及SDA模块,以提高整体效率。体外实验表明,基于CRISPR的基因表达平台表现出优异的CDK5表达抑制效率和对肿瘤细胞的特异性细胞毒性。体外实验,我们发现基于CRISPR的基因表达平台可以通过T细胞介导的细胞毒性选择性杀死膀胱癌细胞.我们的设计具有转基因治疗的重要辅助潜力,并可能提供治疗其他需要转基因治疗的疾病的能力。
    The development of compact CRISPR systems has facilitated delivery but has concurrently reduced gene editing efficiency, thereby limiting the further utilization of CRISPR systems. Enhancing the efficiency of CRISPR systems poses a challenging task and holds significant implications for the advancement of biotechnology. In our work, we report a synthetic dual-antibody system that can stably exist in the intracellular environment, specifically inhibiting the functions of NF-κB and β-catenin. This not only elevates the transgenic expression of the CRISPR system by suppressing the innate immune response within cells to enhance the gene editing efficiency but also demonstrates a notable tumor inhibitory effect. Based on the specific output expression regulation of CRISPR-CasΦ, we constructed a CRISPR-based gene expression platform, which includes sensor modules for detecting intracellular β-catenin and NF-κB, as well as an SDA module to enhance overall efficiency. In vitro experiments revealed that the CRISPR-based gene expression platform exhibited superior CDK5 expression inhibition efficiency and specific cytotoxicity towards tumor cells. In vitro experiments, we found that CRISPR-based gene expression platforms can selectively kill bladder cancer cells through T cell-mediated cytotoxicity. Our design holds significant assistant potential of transgene therapy and may offer the capability to treat other diseases requiring transgene therapy.
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  • 文章类型: Journal Article
    CD47是SIRPα的配体,巨噬细胞表达的抑制性受体,树突状细胞,和自然杀伤(NK)细胞,and,因此,CD47的转基因过表达被认为是抑制移植排斥的有效方法。然而,在探索这种方法时,忽略了CD47信号传导的不利影响。这里,我们通过用膜锚(CD47-IgV)替换跨膜和细胞内结构域来构建突变体CD47。在人类和小鼠细胞中,CD47-IgV在细胞表面上有效表达并在体外和体内防止吞噬作用,但不诱导细胞死亡或抑制血管生成。此外,表达转基因CD47-IgV的造血干细胞在移植或分化中没有可检测到的改变.这项研究提供了实现转基因CD47表达的潜在有效手段,这可能有助于生产用于异种移植的基因编辑猪和用于再生医学的低免疫原性多能干细胞。
    CD47 is a ligand of SIRPα, an inhibitory receptor expressed by macrophages, dendritic cells, and natural killer (NK) cells, and, therefore, transgenic overexpression of CD47 is considered an effective approach to inhibiting transplant rejection. However, the detrimental effect of CD47 signaling is overlooked when exploring this approach. Here, we construct a mutant CD47 by replacing the transmembrane and intracellular domains with a membrane anchor (CD47-IgV). In both human and mouse cells, CD47-IgV is efficiently expressed on the cell surface and protects against phagocytosis in vitro and in vivo but does not induce cell death or inhibit angiogenesis. Furthermore, hematopoietic stem cells expressing transgenic CD47-IgV show no detectable alterations in engraftment or differentiation. This study provides a potentially effective means of achieving transgenic CD47 expression that may help to produce gene-edited pigs for xenotransplantation and hypoimmunogenic pluripotent stem cells for regenerative medicine.
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  • 文章类型: Journal Article
    水稻三酮双加氧酶(TDO;也称为HIS1)的转基因表达可以为易感的双子叶作物如大豆提供免受三酮除草剂的保护。三酮是植物羟苯基丙酮酸双加氧酶(HPPD)的植物毒性抑制剂。TDO基因编码铁/2-酮戊二酸依赖性氧化还原酶。我们使用SeMet-SAD定相至3.16µ分辨率获得了TDO的X射线晶体结构。该结构表明TDO具有类似拟南芥2-酮戊二酸铁依赖性加氧酶花色素合酶(ANS)的折叠。不像ANS,这种TDO结构缺乏结合金属或辅因子,我们认为这是因为活性位点上的无序柔性环在空间上受到限制,无法在晶格中正确折叠。质谱的组合,核磁共振,酶活性研究表明,水稻TDO通过一系列步骤氧化甲基磺草酮;首先产生5-羟基甲基磺草酮,然后产生氧基甲基磺草酮。有证据表明,5-羟基甲基磺草酮是一种比甲基磺草酮弱得多的HPPD抑制剂,和氧-甲基磺草酮几乎没有抑制活性。在经过测试的紧密同源物中,只有玉米和水稻TDO具有酶活性和保护植物免受甲基磺草酮的能力。相关序列和结构已经鉴定了TDO活性所必需的四个氨基酸。引入这四种氨基酸赋予高粱中的甲基磺草酮非活性TDO样蛋白活性,这可能会扩大新作物品种对三酮除草剂的抗性。
    The transgenic expression of rice triketone dioxygenase (TDO; also known as HIS1) can provide protection from triketone herbicides to susceptible dicot crops such as soybean. Triketones are phytotoxic inhibitors of plant hydroxyphenylpyruvate dioxygenases (HPPD). The TDO gene codes for an iron/2-oxoglutarate-dependent oxidoreductase. We obtained an X-ray crystal structure of TDO using SeMet-SAD phasing to 3.16 Å resolution. The structure reveals that TDO possesses a fold like that of Arabidopsis thaliana 2-oxoglutarate‑iron-dependent oxygenase anthocyanidin synthase (ANS). Unlike ANS, this TDO structure lacks bound metals or cofactors, and we propose this is because the disordered flexible loop over the active site is sterically constrained from folding properly in the crystal lattice. A combination of mass spectrometry, nuclear magnetic resonance, and enzyme activity studies indicate that rice TDO oxidizes mesotrione in a series of steps; first producing 5-hydroxy-mesotrione and then oxy-mesotrione. Evidence suggests that 5-hydroxy-mesotrione is a much weaker inhibitor of HPPD than mesotrione, and oxy-mesotrione has virtually no inhibitory activity. Of the close homologues which have been tested, only corn and rice TDO have enzymatic activity and the ability to protect plants from mesotrione. Correlating sequence and structure has identified four amino acids necessary for TDO activity. Introducing these four amino acids imparts activity to a mesotrione-inactive TDO-like protein from sorghum, which may expand triketone herbicide resistance in new crop species.
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