化学合成的亮氨酸脑啡肽基因在大肠杆菌中的克隆和表达

化学合成的亮氨酸脑啡肽(LEK)基因与质粒pBR322重组,转化大肠杆菌,经过原位杂交筛选,限制性图谱分析和Southern杂交鉴定,获得一批LEK基因重组体。插入乳糖操纵子(1ac)启动基因控制LEK基因的表达。一个lac转录方向和LEK基因转录方向相同的表达质粒,pLE103,能在大肠杆菌中产生LEK。用放射免疫分析方法检测,LEK的产量可达每毫克细菌蛋白426毫微克。     

一个HBsAg基因在大肠杆菌中的强表达系统

利用筛选启动基因的载体系统,从大肠杆菌染色体DNA中获得一个启动基因片段。在它的控制下HBsAg基因在大肠杆菌中有较强的表达。通过抗-HBs亲和层析柱分离纯化了表达产物。用琼脂糖双扩散免疫分析法和聚丙烯酰胺——SDS凝胶电泳对分离纯化的表达产物进行了鉴定。     

adr亚型乙型肝炎病毒表面抗原基因在大肠杆菌中的表达

利用adr亚型乙型肝炎病毒(HBV)DNA克隆株,组建表面抗原(HBsAg)基因表达质粒。用竞争性抑制放射免疫分析方法和聚丙烯酰胺——SDS凝胶电泳检测表达产物,获得了含HBsAg的杂合多肽。     

A NEW SYSTEM FOR THE SYNTHESIS OF HIGH LEVELS OF HBsAg SEQUENCE IN Escherichia coli

Using a system to study promoter activity, we have obtained a promoter fragment from E. coli chromosomal DNA. The HBsAg geno under the control of this promoter could be expressed in E. coli. The expression products are isolated and purified by means of a column of anti-HBs cross-linked to Sepharose 4 B. The pure products are characterized through the double diffusion method on 0.6% agarose and polyacrylamido-SDS gel electrophoresis. The synthesis of high levels of HBsAg sequences in E. coli is confirmed.     

EXPRESSION OF SURFACE ANTIGEN GENE OF HUMAN HEPATITIS B VIRUS SEROTYPE adr IN Escherichia coli

The construction of an expression plasmid of hepatitis B virus surface antigen (HBsAg) gone from the cloned hepatitis B virus (HBV) genome subtype adr is reported. The expression products of this plasmid in E. coli were detected by means of radioimmunoassay in competitive suppression and polyacrylamide-SDS gel electrophoresis. The presence of a fusion protein containing HBsAg was confirmed.     

THE CLONING AND EXPRESSION OF THE SYNTHETIC LEU-ENKEPHALIN GENE IN E.coli

The synthetic leu-enkephalin (LEK) gene was joined with pBR322 and transformed toE. coli. The recombinant plasmids containing the LEK gene were selected by colony hybri-dization, and characterized by restriction mapping and Southern's technique. The lac operonwas used to control the expression of the LEK gene. A recombinant plasmid, pEL 103, inwhich the lac operon and LEK gene are transcribed in the same direction, produces LEK inE. coli. The level of LEK detected by radioimmunoassay reaches 426 ng per mg of bacte-rial protein.     

酵母RNA聚合酶Ⅱ体外转录系统的研究

利用酵母核抽提物研究了酵母ADH1和PHO5基因的体外转录反应。以特异的RNA探针检测,首次得到了PHO5和ADH1基因启动子的体外转录产物。体外转录反应被低浓度的α-鹅膏蕈碱所抑制。PHO5基因可以在体外与体内一致或接近的位点正确起始。体外转录反应与模板的量在一定范围内呈线性关系。缺失酵母启动子的模板不能给出转录产物。     

酵母PHO4基因的结构改造与功能分析

酵母PHO4基因编码的蛋白质是阻遏型酸性磷酸酯酶基因表达系统中的正调控因子。本文根据由核苷酸序列推导的氨基酸序列对PHO4蛋白的结构域作了分析。通过寡聚核苷酸的插入或片段的缺失对PHO4基因的编码区进行改造,观察它们在细胞内对酸性磷酸酯酶基因表达的影响,推测不同结构区的功能作用。结果表明PHO4蛋白的第162到171位附近的氨基酸残基可能组成一个与负调控因子PHO80相互作用的功能区。