Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis...Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis substrates. The residues D80DDG in West Nile virus (WNV) NS2B are important for protease activity. To investigate the effects of D80DDG in NS2B on protease activity and viral replication, the negatively charged region D80DD and the conserved residue G83 of NS2B were mutated (D80DD/E80EE, D80DD/K80KK, D80DD/A80AA, G83F, G83S, G83D, G83K, and G83A), and NS3 D75A was designated as the negative control. The effects of the mutations on NS2B-NS3 activity, viral translation, and viral RNA replication were analyzed using kinetic analysis of site-directed enzymes and a transient replicon assay. All substitutions resulted in significantly decreased enzyme activity and blocked RNA replication. The negative charge of D80DD is not important for maintaining NS2B function, but side chain changes in G83 have dramatic effects on protease activity and RNA replication. These results demonstrate that NS2B is important for viral replication and that D80DD and G83 substitutions prevent replication; they will be useful for understanding the relationship between NS2B and NS3.展开更多
【目的】圣路易斯脑炎病毒(St. Louis encephalitis virus,SLEV)属于黄病毒科,是一种单股正链RNA病毒。黄病毒编码的非结构蛋白NS3在病毒复制以及多聚蛋白加工过程中起着重要作用,NS2B是其发挥作用的重要辅助因子。因此,NS2B-NS3蛋白酶...【目的】圣路易斯脑炎病毒(St. Louis encephalitis virus,SLEV)属于黄病毒科,是一种单股正链RNA病毒。黄病毒编码的非结构蛋白NS3在病毒复制以及多聚蛋白加工过程中起着重要作用,NS2B是其发挥作用的重要辅助因子。因此,NS2B-NS3蛋白酶复合物是抗病毒药物的重要靶标。本研究旨在构建SLEV NS2B-NS3蛋白酶的原核表达系统并建立其抑制剂的高通量筛选方法,从而发现其小分子抑制剂。【方法】通过PCR扩增SLEVNS2B-NS3蛋白的编码区,构建原核表达质粒;在大肠杆菌BL21(DE3)中,经异丙基硫代半乳糖苷(Isopropyl β-D-thiogalactoside)诱导得到可溶性的NS2B-NS3蛋白,并用镍亲和层析方法进行纯化;基于荧光共振能量转移(Fluorescence resonance energy transfer)技术检测NS2B-NS3蛋白酶活性,建立其抑制剂的高通量筛选平台。【结果】SLEV NS2B-NS3蛋白酶纯化程度高达95%以上,基于酶活测定的抑制剂筛选平台准确可行。对700多个上市药物进行筛选后,发现原花青素对SLEVNS2B-NS3蛋白酶具有明显的抑制活性。【结论】本研究为SLEVNS2B-NS3蛋白酶抑制剂提供了一种操作方便、高通量的筛选方法,并首次发现了原花青素具有抑制SLEV NS2B-NS3蛋白酶活性的功能,可以作为治疗SLEV感染的潜在靶向药物。展开更多
Dengue is a severe mosquito-borne viral infection causing half a million deaths annually. Dengue virus NS2B/NS3 protease is a validated target for anti-dengue drug design. A series of hitherto unreported 3,5-bis(aryli...Dengue is a severe mosquito-borne viral infection causing half a million deaths annually. Dengue virus NS2B/NS3 protease is a validated target for anti-dengue drug design. A series of hitherto unreported 3,5-bis(arylidene)-4-piperidones analogues 4a4j were synthesized and screened in silico against DENV2 NS2B/NS3 protease to elucidate their binding mechanism and orientation around the active sites. Results were validated through an in vitro DENV2 NS2B/NS3 protease assay using a fluorogenic Boc-Gly-Arg-Arg-AMC substrate. Nitro derivatives of 3,5-bis(arylidene)-4-piperidones (4e and 4j) emerged as promising lead molecules for novel protease inhibitors with an IC<sub>50</sub> of 15.22 and 16.23 µmol/L, respectively, compared to the standard, panduratin A, having IC<sub>50</sub> of 57.28 µmol/L.展开更多
基金Supported by Important National Science& Technology Specific Projects (2012ZX10004403,2012ZX10004219)
文摘Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis substrates. The residues D80DDG in West Nile virus (WNV) NS2B are important for protease activity. To investigate the effects of D80DDG in NS2B on protease activity and viral replication, the negatively charged region D80DD and the conserved residue G83 of NS2B were mutated (D80DD/E80EE, D80DD/K80KK, D80DD/A80AA, G83F, G83S, G83D, G83K, and G83A), and NS3 D75A was designated as the negative control. The effects of the mutations on NS2B-NS3 activity, viral translation, and viral RNA replication were analyzed using kinetic analysis of site-directed enzymes and a transient replicon assay. All substitutions resulted in significantly decreased enzyme activity and blocked RNA replication. The negative charge of D80DD is not important for maintaining NS2B function, but side chain changes in G83 have dramatic effects on protease activity and RNA replication. These results demonstrate that NS2B is important for viral replication and that D80DD and G83 substitutions prevent replication; they will be useful for understanding the relationship between NS2B and NS3.
基金The Research University Team Grant (RUT/1001/PKIMIA/855006) provided by Universiti Sains Malaysia(USM)
文摘Dengue is a severe mosquito-borne viral infection causing half a million deaths annually. Dengue virus NS2B/NS3 protease is a validated target for anti-dengue drug design. A series of hitherto unreported 3,5-bis(arylidene)-4-piperidones analogues 4a4j were synthesized and screened in silico against DENV2 NS2B/NS3 protease to elucidate their binding mechanism and orientation around the active sites. Results were validated through an in vitro DENV2 NS2B/NS3 protease assay using a fluorogenic Boc-Gly-Arg-Arg-AMC substrate. Nitro derivatives of 3,5-bis(arylidene)-4-piperidones (4e and 4j) emerged as promising lead molecules for novel protease inhibitors with an IC<sub>50</sub> of 15.22 and 16.23 µmol/L, respectively, compared to the standard, panduratin A, having IC<sub>50</sub> of 57.28 µmol/L.
