Reigadas Sandrine, Pacheco Almudena, Ramajo Jorge, López de Quinto Sonia, Martinez-Salas Encarnacion
Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049, Madrid, Spain.
FEBS Lett. 2005 Dec 19;579(30):6803-8. doi: 10.1016/j.febslet.2005.11.015. Epub 2005 Nov 28.
Internal ribosome entry site (IRES) elements allow simultaneous synthesis of multiple proteins in eukaryotic cells. Here, two unrelated IRESs that perform efficiently in bicistronic constructs, the picornavirus foot-and-mouth disease virus (FMDV) and the cellular immunoglobulin heavy chain binding protein (BiP) IRES, were used to generate a tricistronic vector. Functional analysis of the tricistronic RNA evidenced that the efficiency of protein synthesis under the control of BiP IRES was lower than that of the FMDV IRES, relative to the efficiency measured in bicistronic vectors. A specific competition between these elements was verified using two separate mono- or bicistronic constructs in vivo and in vitro. In contrast, no interference was detected with the hepatitis C virus (HCV) IRES. The interference effect of FMDV IRES was observed in cis and trans, in support of competition for common transacting factors different than those used in cap- and HCV-dependent initiation.
内部核糖体进入位点（IRES）元件可使真核细胞中同时合成多种蛋白质。在此，利用在双顺反子构建体中高效发挥作用的两种不相关的IRES，即微小核糖核酸病毒口蹄疫病毒（FMDV）和细胞免疫球蛋白重链结合蛋白（BiP）IRES，构建了一个三顺反子载体。对三顺反子RNA的功能分析表明，相对于在双顺反子载体中测得的效率，在BiP IRES控制下的蛋白质合成效率低于FMDV IRES。利用两种单独的单顺反子或双顺反子构建体在体内和体外验证了这些元件之间的特异性竞争。相比之下，未检测到与丙型肝炎病毒（HCV）IRES的干扰。FMDV IRES的干扰效应在顺式和反式中均有观察到，这支持了其与帽依赖性起始和HCV依赖性起始所使用的不同共同反式作用因子存在竞争。
