Kim Seong K, Jang Hyung K, Albrecht Randy A, Derbigny Wilbert A, Zhang Yunfei, O'Callaghan Dennis J
Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
J Virol. 2003 Feb;77(4):2675-85. doi: 10.1128/jvi.77.4.2675-2685.2003.
The equine herpesvirus 1 (EHV-1) immediate-early (IE) and EICP0 proteins are potent trans-activators of EHV-1 promoters; however, in transient-transfection assays, the IE protein inhibits the trans-activation function of the EICP0 protein. Assays with IE mutant proteins revealed that its DNA-binding domain, TFIIB-binding domain, and nuclear localization signal may be important for the antagonism between the IE and EICP0 proteins. In vitro interaction assays with the purified IE and EICP0 proteins indicated that these proteins interact directly. At late times postinfection, the IE and EICP0 proteins colocalized in the nuclei of infected equine cells. Transient-transfection assays showed that the EICP0 protein trans-activated EHV-1 promoters harboring only a minimal promoter region (TATA box and cap site), suggesting that the EICP0 protein trans-activates EHV-1 promoters by interactions with general transcription factor(s). In vitro interaction assays revealed that the EICP0 protein interacted directly with the basal transcription factors TFIIB and TBP and that the EICP0 protein (amino acids [aa] 143 to 278) mediated the interaction with aa 125 to 174 of TFIIB. Our unpublished data showed that the IE protein interacts with the same domain (aa 125 to 174) of TFIIB and with TBP. Taken together, these results suggested that interaction of the EICP0 protein with the IE protein, TFIIB, and TBP may mediate the antagonism between the IE and EICP0 proteins.
马疱疹病毒1型（EHV-1）的立即早期（IE）蛋白和EICP0蛋白是EHV-1启动子的有效反式激活因子；然而，在瞬时转染试验中，IE蛋白抑制EICP0蛋白的反式激活功能。对IE突变蛋白的试验表明，其DNA结合结构域、TFIIB结合结构域和核定位信号可能对IE蛋白和EICP0蛋白之间的拮抗作用很重要。对纯化的IE蛋白和EICP0蛋白进行的体外相互作用试验表明，这些蛋白直接相互作用。在感染后期，IE蛋白和EICP0蛋白在被感染的马细胞的细胞核中共定位。瞬时转染试验表明，EICP0蛋白可反式激活仅含有最小启动子区域（TATA盒和帽位点）的EHV-1启动子，这表明EICP0蛋白通过与一般转录因子相互作用来反式激活EHV-1启动子。体外相互作用试验表明，EICP0蛋白直接与基础转录因子TFIIB和TBP相互作用，并且EICP0蛋白（氨基酸[aa]143至278）介导了与TFIIB的aa 125至174的相互作用。我们未发表的数据表明，IE蛋白与TFIIB的相同结构域（aa 125至174）以及TBP相互作用。综上所述，这些结果表明EICP0蛋白与IE蛋白、TFIIB和TBP的相互作用可能介导了IE蛋白和EICP0蛋白之间的拮抗作用。
