目的探讨是否能够通过噬菌体展示技术筛选与肠致病性大肠埃希菌(EPEC)关键蛋白EspB结合的短肽。方法采用体外大肠埃希菌中表达和纯化EspB蛋白情况,Western blot验证蛋白的表达;Ph.D.12-蛋氨酸噬菌体展示技术用来筛选EspB特异结合蛋白;EL...目的探讨是否能够通过噬菌体展示技术筛选与肠致病性大肠埃希菌(EPEC)关键蛋白EspB结合的短肽。方法采用体外大肠埃希菌中表达和纯化EspB蛋白情况,Western blot验证蛋白的表达;Ph.D.12-蛋氨酸噬菌体展示技术用来筛选EspB特异结合蛋白;ELISA方法用来鉴定这些特异性结合蛋白与EspB的亲和力。结果 Western blot验证从pET21b-EspB转染质粒中提取的EspB蛋白。噬菌体展示技术筛选出了噬菌体6、7、8、12候选蛋白,ELISA检测结果显示这些候选蛋白与EspB蛋白的亲和力高于对照蛋白。结论我们的数据提供了一种潜在的研究策略即通过靶向结合EspB蛋白可抑制EPEC对上皮细胞的粘附。展开更多
Mycosin-1 protease(MycP1)is a serine protease anchored to the inner membrane of Mycobacterium tuberculosis,and is essential in virulence factor secretion through the ESX-1 type VII secretion system(T7SS).Bacterial phy...Mycosin-1 protease(MycP1)is a serine protease anchored to the inner membrane of Mycobacterium tuberculosis,and is essential in virulence factor secretion through the ESX-1 type VII secretion system(T7SS).Bacterial physiology studies demonstrated that MycP1 plays a dual role in the regulation of ESX-1 secretion and virulence,primarily through cleavage of its secretion substrate EspB.MycP1 contains a putative N-terminal inhibitory propeptide and a catalytic triad of Asp-His-Ser,classic hallmarks of a sub-tilase family serine protease.The MycP1 propeptide was previously reported to be initially inactive and activated after prolonged incubation.In this study,we have deter-mined crystal structures of MycP1 with(MycP124-422)and without(MycP1^(63-422))the propeptide,and conducted EspB cleavage assays using the two proteins.Very high struc-tural similarity was observed in the two crystal structures.Interestingly,protease assays demonstrated positive EspB cleavage for both proteins,indicating that the putative propeptide does not inhibit protease activity.Molecu-lar dynamic simulations showed higher rigidity in regions guarding the entrance to the catalytic site in MycP124-422 than in MycP1^(63-422),suggesting that the putative propeptide might contribute to the conformational stability of the active site cleft and surrounding regions.展开更多
文摘目的探讨是否能够通过噬菌体展示技术筛选与肠致病性大肠埃希菌(EPEC)关键蛋白EspB结合的短肽。方法采用体外大肠埃希菌中表达和纯化EspB蛋白情况,Western blot验证蛋白的表达;Ph.D.12-蛋氨酸噬菌体展示技术用来筛选EspB特异结合蛋白;ELISA方法用来鉴定这些特异性结合蛋白与EspB的亲和力。结果 Western blot验证从pET21b-EspB转染质粒中提取的EspB蛋白。噬菌体展示技术筛选出了噬菌体6、7、8、12候选蛋白,ELISA检测结果显示这些候选蛋白与EspB蛋白的亲和力高于对照蛋白。结论我们的数据提供了一种潜在的研究策略即通过靶向结合EspB蛋白可抑制EPEC对上皮细胞的粘附。
基金This work was supported by funds from the National Basic Research Program(973 Program)(Nos.2011CB911104 and 2012CB917202)the National Natural Science Foundation of China(Grant No.31100538)to F.W.,(Grant No.31170817)to C.T.
文摘Mycosin-1 protease(MycP1)is a serine protease anchored to the inner membrane of Mycobacterium tuberculosis,and is essential in virulence factor secretion through the ESX-1 type VII secretion system(T7SS).Bacterial physiology studies demonstrated that MycP1 plays a dual role in the regulation of ESX-1 secretion and virulence,primarily through cleavage of its secretion substrate EspB.MycP1 contains a putative N-terminal inhibitory propeptide and a catalytic triad of Asp-His-Ser,classic hallmarks of a sub-tilase family serine protease.The MycP1 propeptide was previously reported to be initially inactive and activated after prolonged incubation.In this study,we have deter-mined crystal structures of MycP1 with(MycP124-422)and without(MycP1^(63-422))the propeptide,and conducted EspB cleavage assays using the two proteins.Very high struc-tural similarity was observed in the two crystal structures.Interestingly,protease assays demonstrated positive EspB cleavage for both proteins,indicating that the putative propeptide does not inhibit protease activity.Molecu-lar dynamic simulations showed higher rigidity in regions guarding the entrance to the catalytic site in MycP124-422 than in MycP1^(63-422),suggesting that the putative propeptide might contribute to the conformational stability of the active site cleft and surrounding regions.
