应用通用转录器工程获得优良农艺性状的转基因水稻

为得到农艺性状或抗逆性优良的转基因水稻材料,克隆了粳稻品种中花11(ZH11)的通用转录因子TATA框结合蛋白TBP(TATA binding protein)基因,通过随机诱变PCR的方法,获得104个突变子;利用农杆菌介导的方法将这些突变的TBP基因分别转化到中花11中,获得了水稻TBP基因不同突变的转基因水稻。将其移入大田,收获种子并在T1、T2代进行农艺性状的考察,对产量性状改善的转基因材料进行百草枯、甘露醇、氯化钠的胁迫处理,观察并记录表型变化。最终获得了1个具有较高产量同时具有一定非生物逆境抗性的突变体材料。     

龙眼胚性愈伤组织线粒体ATP合酶β亚基基因克隆及其在龙眼体胚发生过程中的表达分析

【目的】克隆龙眼(Dimocarpus longan Lour.)胚性愈伤组织线粒体ATP合酶β亚基基因(mitochondrial F1-ATPase beta subunit gene),并分析该基因在龙眼体胚发生过程中的表达情况。【方法】采用RT-PCR结合RACE法,通过T/A克隆测序,获得龙眼胚性愈伤组织线粒体ATP合酶β亚基基因全长序列;随后通过实时荧光定量PCR(qRT-PCR)法研究该基因在龙眼体胚发生过程中的表达规律。【结果】成功克隆龙眼胚性愈伤组织线粒体ATP合酶β亚基基因完整cDNA序列(GenBank登录号:FJ222749),该序列全长2099bp,由1677bp核苷酸组成的ORF,编码558个氨基酸。该基因与其它植物的线粒体ATP合酶β亚基基因在核苷酸序列和推导的氨基酸序列方面相似性较高。对来源于动、植物的28条线粒体ATP合酶β亚基基因编码区序列所构建的进化树分析表明,由线粒体ATP合酶β亚基基因编码区序列所建立的系统关系树与真实的动、植物进化基本一致,龙眼处在双子叶植物中,由于该基因在龙眼同科属的植物中为首次克隆,所以有自己单独的分支。qRT-PCR结果分析表明,随着龙眼体胚的发育,线粒体ATP合酶β亚基基因转录水平逐渐升高,到球形胚阶段达到最高,而后又急剧下降,到鱼雷形胚阶段降到最低,子叶形胚阶段略有升高。【结论】龙眼线粒体ATP合酶β亚基基因与其它植物相应序列具有较高同源性,在龙眼体胚发育过程中,以球形胚阶段的表达最高。     

GPCR engineering yields high-resolution structural insights into beta2-adrenergic receptor function

The beta2-adrenergic receptor (beta2AR) is a well-studied prototype for heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) that respond to diffusible hormones and neurotransmitters. To overcome the structural flexibility of the beta2AR and to facilitate its crystallization, we engineered a beta2AR fusion protein in which T4 lysozyme (T4L) replaces most of the third intracellular loop of the GPCR ("beta2AR-T4L") and showed that this protein retains near-native pharmacologic properties. Analysis of adrenergic receptor ligand-binding mutants within the context of the reported high-resolution structure of beta2AR-T4L provides insights into inverse-agonist binding and the structural changes required to accommodate catecholamine agonists. Amino acids known to regulate receptor function are linked through packing interactions and a network of hydrogen bonds, suggesting a conformational pathway from the ligand-binding pocket to regions that interact with G proteins.     

植物WRKY转录因子研究进展

转录因子在植物的生长发育及其对外界环境的反应中起着重要的调控作用。典型的转录因子含有DNA结合域,转录调控域,寡聚化位点和核定位信号,转录因子通过这些结构域与相应的顺式元件相互作用调控基因的表达。WRKY转录因子是植物中特有的N-端含有WRKYGQK高度保守氨基酸序列的一种转录调控因子,它能够与(T)(T)TGAC(C/T)序列(W-box)发生特异性结合,从而调节启动子中含W-box元件的调节基因和/或功能基因的表达,参与植物的各种生理生化反应。文章主要论述近年来植物WRKY转录因子的相关研究进展。     

A pituitary N-acetylgalactosamine transferase that specifically recognizes glycoprotein hormones

The glycoprotein hormones lutropin (LH) and follitropin (FSH), which have common alpha-subunits but hormone-specific beta-subunits, are both synthesized in the gonadotroph. However, they bear Asn-linked oligosaccharides that differ in structure. Those on LH terminate with the sequence SO4-4GalNAc beta 1----4GlcNAc beta 1----2Man alpha, whereas those on FSH terminate with the sequence sialic acid alpha-Gal beta 1----4GlcNAc beta 1----2Man alpha. A GalNAc-transferase was identified in bovine pituitary membranes that recognizes features of the alpha-subunit peptide and adds GalNAc to its oligosaccharides with an apparent Michaelis constant of 25 micromolar. The different patterns of glycosylation for LH and FSH indicate that access to the protein recognition marker on the alpha-subunit is modulated by the associated beta-subunit. The tightly regulated synthesis of sulfated and sialylated oligosaccharides on the pituitary glycoprotein hormones suggests these oligosaccharides have an important biological role.     

RNA elimination machinery targeting meiotic mRNAs promotes facultative heterochromatin formation

Facultative heterochromatin that changes during cellular differentiation coordinates regulated gene expression, but its assembly is poorly understood. Here, we describe facultative heterochromatin islands in fission yeast and show that their formation at meiotic genes requires factors that eliminate meiotic messenger RNAs (mRNAs) during vegetative growth. Blocking production of meiotic mRNA or loss of RNA elimination factors, including Mmi1 and Red1 proteins, abolishes heterochromatin islands. RNA elimination machinery is enriched at meiotic loci and interacts with Clr4/SUV39h, a methyltransferase involved in heterochromatin assembly. Heterochromatin islands disassemble in response to nutritional signals that induce sexual differentiation. This process involves the antisilencing factor Epe1, the loss of which causes dramatic increase in heterochromatic loci. Our analyses uncover unexpected regulatory roles for mRNA-processing factors that assemble dynamic heterochromatin to modulate gene expression.     

一个葡萄抗逆相关转录因子VvPF1基因的in silico克隆及生物信息学分析

AP2/EREBP是植物所特有的一类转录因子,广泛参与植物生长、发育以及多种生理生化反应的信号传导.本文利用in silico克隆方法获得葡萄VvPF1 基因,并利用生物信息学方法对该基因编码产物从氨基酸组成、理化性质、进化关系、二级及三级结构、功能等方面进行预测和分析.结果表明:VvPF1 是一个含有明显AP2结构域,具有潜在核定位能力的ERF类转录因子.此外,VvPF1与CaPF1, JERF1等抗逆相关的转录因子具有较高的同源性,因此推测,VvPF1很可能参与葡萄对生物和非生物胁迫的信号传导.     

基于转录组的漆树MYB转录因子的筛选及分析

MYB转录因子家族是植物最大的转录因子家族之一,在植物生长发育、形态建成、次生代谢等的调控中起着重要作用。本研究在漆树转录组测序的基础上,应用生物信息学方法,筛选到48个漆树MYB转录因子,依据MYB保守域的特点将其分为3类:1条R₃-MYB 序列,21条R₂R₃-MYB序列和26条R₁-MYB序列。结果表明,蛋白序列分析显示,48条漆树MYB转录因子大部分属疏水性蛋白,且无规则卷曲和α螺旋在二级结构中占有较大比例。GO分析发现漆树R₂R₃-MYB蛋白共注释到生物学过程、细胞组分和分子功能3大类功能的27个亚类。系统进化分析将48个漆树MYB转录因子分为了8个亚组。表达谱数据分析表明,漆树MYB基因的表达具有组织特异性,11个在叶片中高水平表达,21个在茎中的表达量较高。研究结果为今后进一步解析漆树MYB转录因子的结构和生物学功能奠定基础,有助于进一步研究漆树MYB转录因子在次生代谢产物中的调控功能。