人线粒体tRNALeu(UUR)基因A3243G点突变对其亮氨酰化活性的影响

化学法合成人线粒体野生型与A3243G点突变型tRNALeu(UUR)基因,体外转录生成相应的tRNALeu(UUR),表达并纯化人线粒体亮氨酰tRNA合成酶(mtLeuRS),用mtLeuRS催化野生型与突变型tRNALeu(UUR)与亮氨酸结合,分别检测两种类型tRNALeu(UUR)的氨酰化动力学常数。结果表明,野生型tRNALeu(UUR)的Km/Kcat仅为突变型tRNALeu(UUR)的63.9%,A3243G点突变使tRNALeu(UUR)接受亮氨酸的能力明显下降,提示此为A3243G点突变致病机制之一。 Abstract:The wild-type and mutant-type human mitochondrial tRNALeu(UUR) genes were synthesized and transcribed in vitro with T7 RNA polymerase.The kinetic parameters of human mitochondrial leucyl-tRNA synthetase(mtLeuRS) were determined with wild-type and mutant-type human mitochondrial tRNALeu(UUR) respectively.The results show that the value of Km/Kcat of mtLeuRS for the mutant-type tRNALeu(UUR) is 63.9% as compared with the wild-type.Human mitochondrial tRNALeu(UUR) gene A3243G point mutant can remarkably reduce it′s aminoacylation activity,suggesting it would be one of the mechanisms that the mutation could produce such clinical phenotypes.     

人线粒体tRNALeu(UUR)及其突变体的基因克隆、表达和纯化

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.     

汉坦病毒H8205株G1P基因片段重组杆状病毒表达载体的构建及表达

将汉坦病毒H8205株G1P基因的保守序列(约1000bp)作为目的基因插入到BactoBac杆状病毒表达系统的pFastBacHTb供体质粒中,利用Tn7转座子同BacmidDNA同源重组,获得了含目的基因片段的重组杆状病毒DNA,并利用其转染Sf9昆虫细胞,72h后收集细胞悬液,再用该悬液侵染Sf9昆虫细胞,48h后收获病毒.采用IFA分析收获的产物,观察到了特异性的荧光,并且采用SDSPAGE和Western印迹也获得了与预期一致的结果.证明感染后的Sf9昆虫细胞所表达的蛋白中含有能与抗汉坦病毒H8205株多克隆抗体特异性结合目的蛋白.研究表明,采用杆状病毒表达系统可以成功表达出汉坦病毒H8205株包膜糖蛋白G1基因片段,为开发适合的以G1P为抗原的汉坦病毒诊断试剂进行了前期的探索.     

Gene cloning, expression and purification of human mitochondrial tRNA~(Leu(UUR)) and its mutant

Genes of human mitochondrial tRNALeu(UUR) (mtRNALeu(UUR)) and its mutant (mtRNALeu(M)) were synthesized and inserted into the plasmid pGEM-9Zf(-) respectively. E.coli JM 109 was transformed by the recombinant plasmids containing the target genes. The mtRNALeu(UUR) and mtRNALeu(M) were expressed up to 19.10% and 17.76% of total small RNA respectively. They were purified to 54% homogeneity by DEAE-sepharose-CL4B column chromatography and finally repu-rified by 15% PAGE/urea. Their kinetic parameters for E.coli LeuRS were measured. The results showed that the value of kcal/Km of mtRNALeu(M) was about one fifth of that of mtRNALeu(UUR) and indicated the leucine acceptability of mtRNALeu(M) was much lower than that of mtRNALeu(UUR).     

肝刺激因子对实验性肝纤维化大鼠的保护作用

肝刺激因子对实验性肝纤维化大鼠的保护作用＊韩伟国杨伟珠程建军（镇江医学院临床生化教研室,镇江２１２００１）肝刺激因子（ＨＳＳ）对肝损伤的保护作用已有许多资料论证。本工作以实验性大鼠肝纤维化为模型,观察肝刺激因子（ＨＳＳ）对大鼠肝纤维化发生发展过程的影...