磷脂酶A1辅助蛋白N端截短菌株的构建及其优化表达

根据GenBank公布的磷脂酶A1辅助蛋白plaS基因序列,通过生物信息学软件分析,截短辅助蛋白PlaS的N端35AA。将截短后的辅助蛋白plaS基因经PCR扩增技术与原核表达载体pET-28a(+)连接,再转化到BL21(DE3)宿主菌中进行融合表达,从而成功构建dSP28表达菌株。用异丙基-β-D-硫代半乳糖苷(isopropy-β-D-thiogalactoside,IPTG)诱导辅助蛋白表达,对诱导时间、IPTG浓度、起始菌体浓度(OD_(600nm))和温度逐项进行优化,摸索得到辅助蛋白的最佳诱导表达条件为诱导时间8 h,IPTG浓度0.2 mmol/L,起始体浓度(OD_(600nm))0.7,温度40℃,转速200 r/min。在此条件下,对P28、SP28和dSP28发酵中OD_(600nm)进行测定,结果表明,加入IPTG诱导后P28和dSP28能够快速的增殖,且诱导8 h后仍显示增长趋势,而SP28的生长受到明显的抑制作用。

Phosphatidylserine-Specific Phospholipase A1 is the Critical Bridge for Hepatitis C Virus Assembly

The phosphatidylserine-specific phospholipase A1(PLA1A)is an essential host factor in hepatitis C virus(HCV)assembly.In this study,we mapped the E2,NS2 and NS5A involved in PLA1A interaction to their lumenal domains and membranous parts,through which they form oligomeric protein complexes to participate in HCV assembly.Multiple regions of PLA1A were involved in their interaction and complex formation.Furthermore,the results represented structures with PLA1A and E2 in closer proximity than NS2 and NS5A,and strongly suggest PLA1 A-E2,s physical interaction in cells.Meanwhile,we mapped the NS5A sequence which participated in PLA1A interaction with the C-terminus of domain 1.Interestingly,these amino acids in the sequence are also essential for viral RNA replication.Further experiments revealed that these four proteins interact with each other.Moreover,PLA1A expression levels were elevated in livers from HCV-infected patients.In conclusion,we exposed the structural determinants of PLA1A,E2,NS2 and NS5A proteins which were important for HCV assembly and provided a detailed characterization of PLA1A in HCV assembly.