人程序性死亡受体配体1免疫球蛋白可变区结构域基因酵母双杂交诱饵质粒的构建及其自激活检测

Construction and self-activation detection of yeast two-hybrid bait plasmid of human programmed cell death ligand 1 immunoglobulin variable region domain gene

目的 构建人程序性死亡受体配体1(programmed cell death ligand 1,PD-L1)免疫球蛋白可变区(immunoglobulin variable region,IgV)结构域基因酵母双杂交重组诱饵质粒,检测其在酵母中的表达情况,检测PD-L1 IgV蛋白细胞毒性和自我激活,以及PD-L1 IgV与人硫氧还蛋白(human thioredoxin,hTrx)之间的相互作用情况。方法 利用生物信息学方法对人PD-L1进行分析,并根据NCBI GenBank数据库中登录的PD-L1基因编码区序列设计扩增PD-L1 IgV结构域的引物,以pENTER-PD-L1质粒为模板进行PCR扩增,克隆至酵母双杂交诱饵载体pGBKT7。将鉴定正确的重组诱饵质粒及pGBKT7空载体分别转化至Y2HGold酵母细胞,PCR及Western blot法检测PD-L1 IgV基因及蛋白的表达;同时检测PD-L1 IgV蛋白毒性及自我激活效应,并采用滴板法检测诱饵蛋白PD-L1 IgV与hTrx相互作用情况。结果 PD-L1的生物信息学分析结果与相关报道一致;成功构建了重组诱饵质粒pGBKT7-PD-L1 IgV,并获得Y2HGold阳性克隆子,PD-L1 IgV能在其中稳定表达。空载体pGBKT7、重组诱饵质粒pGBKT7-PD-L1 IgV在SD/-Trp、SD/-Trp/X-α-Gal平板上生长良好,菌落大小、数量一致,呈白色,在SD/-Trp/X-α-Gal/AbA平板上两者均不生长,表明PD-L1 IgV蛋白对酵母无毒性且无自我激活效应;滴板法试验结果显示,所有实验组在SD/-Trp/-Leu平板上生长良好,仅阳性对照组可在SD/-Trp/-Leu/X-α-Gal/AbA平板上生长且呈蓝色,表明诱饵蛋白PD-L1 IgV、hTrx不存在自我激活现象,且两者之间也不存在相互作用。结论 成功构建了重组人PD-L1 IgV酵母双杂交诱饵质粒,PD-L1 IgV蛋白对酵母细胞无毒性且无自我激活效应,且与hTrx之间无相互作用。后续可利用hTrx构建肽适体文库,从中筛选可与PD-L1 IgV特异结合的肽适体。

Objective To construct a yeast two-hybrid recombinant bait plasmid of human programmed cell death ligand 1(PD-L1)immunoglobulin variable region(IgV)domain gene,detect its expression in yeast and detect the cytotoxicity and self-activation of PD-L1 IgV protein as well as the interaction between PD-L1 IgV and human thioredoxin(hTrx).Methods Human PD-L1 was analyzed by bioinformatics method,and primers were designed to amplify PD-L1 IgV domain based on the coding region of PD-L1 gene registered in NCBI GenBank database.PCR amplification was carried out with pENTERPD-L1 plasmid as template,and then cloned into yeast two-hybrid bait vector pGBKT7.The recombinant bait plasmid and pGBKT7 empty vector were transformed into Y2HGold yeast cells respectively,and the PD-L1 IgV gene and its expression were detected by PCR and Western blot;Meanwhile,the protein toxicity and self-activation of PD-L1 IgV were detected,and the interaction between PD-L1 IgV and hTrx was detected by drip plate method.Results The bioinformatics analysis results of PD-L1 were consistent with related reports.The recombinant bait plasmid pGBKT7-PD-L1 IgV was correctly constructed,and Y2HGold positive clone was obtained,in which PD-L1 IgV was stably expressed.The empty vector pGBKT7 and recombinant bait plasmid pGBKT7-PD-L1 IgV grew well on SD/-Trp and SD/-Trp/X-α-Gal plates with the same colony size and number and white colony,but they did not grow on SD/-Trp/X-α-Gal/AbA plates,which indicated that PD-L1 IgV protein had no toxicity and no self-activation effect on yeast.The results of drip plates test showed that all experimental groups grew well on SD/-Trp/-Leu plate,while only positive control group grew on SD/-Trp/-Leu/X-α-Gal/AbA plate and showed blue color,which indicated that bait protein PD-L1 IgV and hTrx did not self-activate,and there was no interaction between them.Conclusion Recombinant human PD-L1 IgV bait plasmid was successfully constructed.PD-L1 IgV protein showed no toxicity and self-activation effect on yeast cells,and there was no interaction between PD-L1 IgV and hTrx.Subsequently,hTrx can be used to construct a peptide aptamer library,from which peptide aptamers that specifically bind to PD-L1 IgV can be screened.