乙型肝炎病毒X基因的分析与在大肠杆菌中的表达

The Sequence Analysis of the Hepatitis B Virus(HBV)X Gene and Its Expression in E coli System

以ＨＢＶ－ＮＣｌＤＮＡ为材料研究了其中的Ｘ基因，首先确定了此Ｘ基因的顺序，即用ＡＢＩ自动萤光测序议测序证明了此Ｘ基因的３８５位核苷酸后缺失１９个核苷酸，从而引起移码突变，使此Ｘ基因共有５１９个核苷酸，编码１７２个氨基酸，比另一种ａｄｒ型Ｘ蛋白多１８个氨基酸。在其第五位氨基酸上有一ＡＴＧ起始密码，也与另一Ｘ基因不同。经重组后获得在大肠杆菌中的热诱导表达，用Ｗｅｓｔｅｒｎｂｌｏｔ方法证明确为Ｘ蛋白，并有多态性。

Sequencing the X gene with dideoxynucleotides as chain terminators,it shows that this specific X gene is 519 bp long on account of frame shift mutation for the deletion of 19 bp after the 385 th G.So the X gene can encode a protein with 172 amino acids which is 18 amino acids longer than the normal X protein. The gene also owns its specific feature with another ATG initiation codon at the fifth amino acid residue. The X gene was inserted into pBV221 expression plasmid, and the recombinant plasmid PBV221-X was transformed into E coli. The transformed E coli cell induced by heating at 40℃ can expressed the X protein ,and the Western Blot hybridization shows that multiple polypeptides were translated at distinct in-frame ATGs of the X gene.