Smith C A, Crotty S, Harada Y, Frankel A D
Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448, USA.
Biochemistry. 1998 Jul 28;37(30):10808-14. doi: 10.1021/bi980382+.
The bovine immunodeficiency virus (BIV) Tat protein binds with high affinity to its TAR RNA site through a large set of specific RNA-protein contacts whereas human immunodeficiency virus (HIV) Tat makes relatively few contacts to HIV TAR and requires the assistance of a cellular protein to bind with high affinity. The two TAR sites are structurally very similar, but BIV Tat appears unable to make the same set of high-affinity contacts to HIV TAR. To determine the basis of this discrimination, we examined BIV Tat binding to a series of hybrid TARs both in vivo and in vitro. We expected that differences in the architectures of the bulges might account for the binding specificity; however, the results show that flanking base pairs provide the key determinants. Based on these data, we designed a novel TAR that is recognized by both BIV Tat and HIV Tat. This RNA may be viewed as a primordial TAR from which two distinct recognition strategies can be evolved.
牛免疫缺陷病毒（BIV）的Tat蛋白通过大量特定的RNA-蛋白质相互作用与其TAR RNA位点高亲和力结合，而人类免疫缺陷病毒（HIV）的Tat与HIV TAR的相互作用相对较少，并且需要一种细胞蛋白的协助才能高亲和力结合。这两个TAR位点在结构上非常相似，但BIV Tat似乎无法与HIV TAR形成同样的高亲和力相互作用。为了确定这种区分的基础，我们在体内和体外研究了BIV Tat与一系列杂交TAR的结合情况。我们原本认为凸起结构的差异可能解释结合特异性；然而，结果表明侧翼碱基对才是关键决定因素。基于这些数据，我们设计了一种能被BIV Tat和HIV Tat都识别的新型TAR。这种RNA可被视为一种原始TAR，由此可以演化出两种不同的识别策略。
