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为了研究tRNATrp的氨基酸接受茎中除两对半碱基以外的特异性元件,设计并完成了4种水稻线粒体tRNATrp向枯草杆菌tRNATrp的突变体(MPB0,G1A和U5G/A68C;MPB1,C2G/G71C:MPB2,C4G/G69C;MPB3,C2G/G71C和C4G/G69C),体外转录并用枯草杆菌和人这两种不同种属来源的色氨酰tRNA合成酶(TrpRS)测定了这些tRNATrp分子的氨酰化活力(Kcat/KM.结果表明,这些突变体具有被枯草杆菌TrpRS氨酰化的能力,与野生型水稻线粒体tRNATrp>相比,MPB0被枯草杆菌TrpRS氨酰化的活力提高了5倍,MPB1和MPB2被枯草杆菌TrpRS氨酰化的活力分别提高了40和53倍,MPB3则提高了140倍,为野生型枯草杆菌tRNATrp>的34%,而人色氨酰tRNA合成酶氨酰化这4个突变体的活力都很微弱.揭示了水稻线粒体tRNATrp>氨基酸接受茎上的2个碱基对C2/G71和C4/G69的突变,对枯草杆菌TrpRS的识别起重要作用,由此推测,接受茎上的2个碱基对C2/G71和C4/G69也是线粒体tRNATrp>重要的特异性元件. 相似文献
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为了研究tRNA^Trp的氨基酸接受茎中除两对半碱基以外的特异性元件,设计并完成了4种水稻线粒体tRNA^Trp向枯草杆菌tRNA^Trp的突变体（MPB0,G1A和U5G／A68C;MPB1,C2G／G71C;MPB2,C4G／G69C;MPB3,C2G／G71C和C4G／G69C）,体外转录并用枯草杆菌和人这两种不同种属来源的色氨酰tRNA合成酶（TrpRS）N定了这些tRNA^Trp分子的氨酰化活力（Kcat／KM）．结果表明,这些突变体具有被枯草杆菌TrpRS氨酰化的能力,与野生型水稻线粒体tRNA^Trp相比,MPB0被枯草杆菌TrpRS氨酰化的活力提高了5倍,MPB1和MPB2被枯草杆菌TrpRS氨酰化的活力分别提高了40和53倍,MPB3则提高了140倍,为野生型枯草杆菌tRNA^Trp的34％,而人色氨酰tRNA合成酶氨酰化这4个突变体的活力都很微弱．揭示了水稻线粒体tRNA^Trp氨基酸接受茎上的2个碱基对C2／G71和C4／G69的突变,对枯草杆菌TrpRS的识别起重要作用,由此推测,接受茎上的2个碱基对C2／G71和C4／G69也是线粒体tRNA^Trp重要的特异性元件． 相似文献
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为了研究tRNATrp的氨基酸接受茎中除两对半碱基以外的特异性元件,设计并完成了4种水稻线粒体tRNATrp向枯草杆菌tRNATrp的突变体 (MPB0, G1A和U5G/A68C;MPB1,C2G/G71C;MPB2,C4G/G69C;MPB3,C2G/G71C和C4G/G69C),体外转录并用枯草杆菌和人这两种不同种属来源的色氨酰 tRNA 合成酶(TrpRS)测定了这些 tRNATrp 分子的氨酰化活力(Kcat/KM)．结果表明,这些突变体具有被枯草杆菌TrpRS氨酰化的能力,与野生型水稻线粒体tRNATrp相比,MPB0被枯草杆菌TrpRS氨酰化的活力提高了5倍,MPB1和MPB2被枯草杆菌TrpRS氨酰化的活力分别提高了40和53倍,MPB3则提高了140倍,为野生型枯草杆菌tRNATrp的34%,而人色氨酰 tRNA合成酶氨酰化这4个突变体的活力都很微弱．揭示了水稻线粒体tRNATrp氨基酸接受茎上的2个碱基对C2/G71和C4/G69的突变,对枯草杆菌TrpRS的识别起重要作用,由此推测,接受茎上的2个碱基对C2/G71和C4/G69也是线粒体tRNATrp重要的特异性元件． 相似文献
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线粒体tRNA基因可能是原发性高血压发病相关的突变热点区域。文章报道了两个具有母系遗传特征的中国汉族原发性高血压家系的临床和分子遗传学特征。家系先证者和其他成员的临床数据表明,家系中母系成员高血压发病的严重程度存在差异,发病年龄也从36~79岁不等。对两个家系先证者使用24对有部分重叠的引物进行线粒体DNA全序列扩增分析,结果发现这两个先证者均携带同质性的tRNAMet/tRNAGlnA4401G和tRNACysG5821A突变,多态性变异位点都属于东亚单体型C。A4401G突变可能通过影响tRNAMet和tRNAGln前体的加工引起线粒体tRNA代谢水平的改变,而tRNACysG5821A突变位于tRNACys氨基酸受体臂,该突变使tRNACys氨基酸受体臂上原有的G6-C67配对消失,可能影响tRNACys空间结构和功能的稳定性,致使线粒体功能障碍。因此,tRNAMet/tRNAGlnA4401G和tRNACysG5821A突变可能是这两个原发性高血压家系的分子致病基础。 相似文献
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我们测定了鲤鱼线粒体半胱氮酸tRNA 基因和轻链(L 链)复制起始区的核苷酸序列,绘制了半胱氨酸tRNA 三叶草形的二级结构以及L 链复制区的茎环结构。通过五种脊椎动物tRNA~(cya)基因的核苷酸序列分析发现,鲤鱼线粒体tRNA~(cya)基因有许多不同于细胞质tRNA~(cya)基因的不寻常的结构特点。鲤鱼线粒体L 链复制起始区含有36个碱基,复制起始区茎环结构中的茎含有11对碱基,而环则是由14个碱基组成。同其它10种脊椎动物L-链复制起始区的核苷酸序列比较发现,鲤鱼茎环结构中的茎序列是非常保守的,而环的序列及环的长度则变化较大。茎环结构可能在轻链复制中起着重要的作用。 相似文献
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将化学法合成的人线粒体tRNALeu(UUR)及其突变体(tRNALeu(M))基因分别连接到载体pGEM-9zf (-)中, 并转化到大肠杆菌JM109中得到两个转化体分别为Leu-W和Leu-M. 在IPTG的诱导下, tRNALeu(UUR)和tRNALeu(M)的表达量可达总小分子RNA的19.10%和17.76%. 经DEAE-sepherose CL4B柱层析可使它们的纯度提高3倍. 最后用15%的变性聚丙烯酰胺凝胶电泳纯化, 并用大肠杆菌亮氨酰tRNA合成酶(LeuRS)分别测定了它们的氨酰化反应动力学常数. 结果显示, mtRNALeu(M)的Kcat / Km值约为mtRNALeu(UUR) 的1/5, 提示该突变可使mtRNALeu(UUR)的氨基酸接受能力明显下降. 相似文献
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本文以10种限制性内切酶分析雉科中环颈雉,红腹锦鸡和白腹锦鸡线粒体DNA（mtDNA）。雉属与锦鸡属之间的遗传距离P为0.076（0.067-0.085）,红腹锦鸡与白腹锦鸡的P为0.012。推算雉属和锦鸡属的分化大约发生在3.8×10[6]年以前,红腹锦鸡与白腹锦鸡的分化大约在6×10[5]年以前。这些结果表明：1.在雉科系统发生中,雉属与锦鸡属是近缘的属;2.红腹锦鸡和白腹锦鸡的分化较晚,关系密切,可能只是两个亚种。 相似文献
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开放式空气二氧化碳浓度增高(FACE)条件下水稻的根系活力和氮同化能力 总被引：7，自引：1，他引：7
利用FACE(Free Air Carbon-dioxide Enrichment)平台技术,用伤流量法研究了低氮(LN 150 kg·hm-2)和常氮(NN 250 kg·hm-2)水平下,大气CO2浓度升高对水稻分蘖、抽穗期和穗后35 d根系活力和根系N同化能力(氨基酸合成能力)的影响.结果表明,就整株水稻来看, CO2浓度升高和N处理对根系活力无显著影响;但由于FACE条件下水稻分蘖数增加14.5%(LN)和20.7%(NN),使每茎根系活力(伤流强度)降低1.4%～21.7%.在分蘖和抽穗期,虽然FACE处理促进了根系吸收的无机N向氨基酸转化,根系伤流液中氨基酸氮/无机氮提高11.1%～143.1%,但氨基酸浓度和合成总量和对照相比无明显差异.在穗后35 d,FACE处理减弱了水稻根系的N同化能力,表现为根系伤流液中氨基酸/无机氮降低38.1%(LN)和29.2%(NN);同时氨基酸浓度降低34.0%(LN)和44.7%(NN),氨基酸合成总量降低50.8%(LN)和40.0%(NN).提高施氮水平促进了抽穗期水稻根系对无机氮的吸收,伤流液中无机氮含量增加51.1%(对照)和155.2%(FACE),但并未增加氨基酸合成量,由此导致抽穗期氨基酸氮/无机氮显著降低19.5%(对照)和36.8%(FACE);同时,氮处理在这个时期与FACE处理表现出明显的交互作用. 相似文献
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构建了３种来源于水稻、人和啤酒酵母的线粒体ｔＲＮＡ＾Ｔｒｐ基因。实验表明这些线粒体ｔＲＮＡ＾Ｔｒｐ的体外转录产物具有被枯草杆菌色氨酰－ｔＲＮＡ合成酶（ＴｒｐＲＳ）氨酰化的能力,但是不能被鼠肝来源的氨酰ｔＲＮＡ合成酶粗酶所催化。动力学资源常数测定表明枯草杆菌ＴｒｐＲＳ对线粒体ｔＲＮＡ＾Ｔｒｐ的亲和力为野生型ｔＲＮＡ＾Ｔｒｐ的一半,而在催化效率上,水稻和啤酒酵母线粒体ｔＲＮＡ＾Ｔｒｐ的色氨酰化能力比野 相似文献
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识别位碱基Ｇ７３,为ｔＲＮＡ＾Ｔｒｐ的主要个性元件之一,ｔＤＮＡ＾Ｔｒｐ－ＮＣＣｒＡ的氨酰化活力测定及圆二色谱均表明在相同的ｐＨ条件下,识别位碱基的改变将影响到ｔＲＮＡ３′端的构象,而具有同一识别位碱基的ｔＤＮＡ＾Ｔｒｐ在不同ｐＨ条件下,亦显示出不同的构象及氨酰化活力,ｔＤＮＡ＾Ｔｒｐ的研究表明,是ｔＲＮＡ的构象而不是碱基本身决定了ｔＲＮＡ与其相应合成酶之间的精确识别。 相似文献
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Uwe Mueller Yves A. Muller Regine Herbst-Irmer Mathias Sprinzl Udo Heinemann 《Acta Crystallographica. Section D, Structural Biology》1999,55(8):1405-1413
An RNA helix with seven base pairs which was derived from the acceptor stem of Escherichia coli tRNAAla, rGGGGCUA·rUAGCUCC (ALAwt), as well as a variant, rGGGGCUA·rUAGCCCC (ALAC70), in which the single G·U wobble base pair of ALAwt was replaced by G·C, crystallize in space group C2. Both non-isomorphic crystal forms display a complex packing pattern, which can be described alternatively as disorder or pseudo-merohedral twinning. The structure of ALAwt was determined by SIRAS phasing using an isomorphous iodine derivative, rGGGGCi5UA·rUAGCUCC (ALAI). All three RNA structures were subsequently subjected to twin refinement in space group P1, using anisotropic thermal displacement parameters at resolutions of 1.16, 1.23 and 1.4 Å for ALAwt, ALAI and ALAC70, respectively. Alternatively, the structure of ALAwt was refined in space group C2 assuming twofold disorder of the molecular orientation. The refined structures are of reasonable quality according to all available indicators. There are no systematic differences between the molecular models resulting from twin refinement and disorder refinement. 相似文献
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Charlotte Frster Markus Perbandt Arnd B. E. Brauer Svenja Brode Jens P. Fürste Christian Betzel Volker A. Erdmann 《Acta Crystallographica. Section F, Structural Biology Communications》2007,63(1):46-48
The tRNAGly and glycyl‐tRNA synthetase (GlyRS) system is an evolutionary special case within the class II aminoacyl‐tRNA synthetases because two divergent types of GlyRS exist: an archaebacterial/human type and an eubacterial type. The tRNA identity elements which determine the correct aminoacylation process are located in the aminoacyl domain of tRNAGly. To obtain further insight concerning structural investigation of the identity elements, the Escherichia coli seven‐base‐pair tRNAGly acceptor‐stem helix was crystallized. Data were collected to 2.0 Å resolution using synchrotron radiation. Crystals belong to space group P3121 or P3221, with unit‐cell parameters a = b = 35.35, c = 130.82 Å, α = β = 90, γ = 120° and two molecules in the asymmetric unit. 相似文献
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Qiufen He Xiao He Yun Xiao Qiong Zhao Zhenzhen Ye Limei Cui Ye Chen Min-Xin Guan 《The Journal of biological chemistry》2021,297(2)
Mammalian mitochondrial tRNA (mt-tRNA) plays a central role in the synthesis of the 13 subunits of the oxidative phosphorylation complex system (OXPHOS). However, many aspects of the context-dependent expression of mt-tRNAs in mammals remain unknown. To investigate the tissue-specific effects of mt-tRNAs, we performed a comprehensive analysis of mitochondrial tRNA expression across five mice tissues (brain, heart, liver, skeletal muscle, and kidney) using Northern blot analysis. Striking differences in the tissue-specific expression of 22 mt-tRNAs were observed, in some cases differing by as much as tenfold from lowest to highest expression levels among these five tissues. Overall, the heart exhibited the highest levels of mt-tRNAs, while the liver displayed markedly lower levels. Variations in the levels of mt-tRNAs showed significant correlations with total mitochondrial DNA (mtDNA) contents in these tissues. However, there were no significant differences observed in the 2-thiouridylation levels of tRNALys, tRNAGlu, and tRNAGln among these tissues. A wide range of aminoacylation levels for 15 mt-tRNAs occurred among these five tissues, with skeletal muscle and kidneys most notably displaying the highest and lowest tRNA aminoacylation levels, respectively. Among these tissues, there was a negative correlation between variations in mt-tRNA aminoacylation levels and corresponding variations in mitochondrial tRNA synthetases (mt-aaRS) expression levels. Furthermore, the variable levels of OXPHOS subunits, as encoded by mtDNA or nuclear genes, may reflect differences in relative functional emphasis for mitochondria in each tissue. Our findings provide new insight into the mechanism of mt-tRNA tissue-specific effects on oxidative phosphorylation. 相似文献
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Charlotte Frster Norbert Krauss Arnd B. E. Brauer Karol Szkaradkiewicz Svenja Brode Klaus Hennig Jens P. Fürste Markus Perbandt Christian Betzel Volker A. Erdmann 《Acta Crystallographica. Section F, Structural Biology Communications》2006,62(6):559-561
In order to understand elongator tRNASer and suppressor tRNASec identity elements, the respective acceptor‐stem helices have been synthesized and crystallized in order to analyse and compare their structures in detail at high resolution. The synthesis, crystallization and preliminary X‐ray diffraction results for a seven‐base‐pair tRNASer acceptor‐stem helix are presented here. Diffraction data were collected to 1.8 Å, applying synchrotron radiation and cryogenic cooling. The crystals belong to the monoclinic space group C2, with unit‐cell parameters a = 36.14, b = 38.96, c = 30.81 Å, β = 110.69°. 相似文献
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The availability of the draft genome sequence of Oryza sativa L. ssp. indica has made it possible to study the rice tRNA genes. A total of 596 tRNA genes, including 3 selenocysteine tRNA genes and one suppressor tRNA gene are identified in 127551 rice contigs. There are 45 species of tRNA genes and the revised wobble hypothesis proposed by Guthrie and Abelson is perfectly obeyed. The relationship between codon usage and the number of corresponding tRNA genes is discussed. Redundancy may exist in the present list of tRNA genes and novel ones may be found in the future. A set of 33 tRNA genes is discovered in the complete chloroplast genome of Oryza sativa L. ssp. indica. These tRNA genes are identical to those in ssp. japonica identified by us independently from the origional annotation. 相似文献