Szewczak A A, Ortoleva-Donnelly L, Ryder S P, Moncoeur E, Strobel S A
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
Nat Struct Biol. 1998 Dec;5(12):1037-42. doi: 10.1038/4146.
Close packing of several double helical and single stranded RNA elements is required for the Tetrahymena group I ribozyme to achieve catalysis. The chemical basis of these packing interactions is largely unknown. Using nucleotide analog interference suppression (NAIS), we demonstrate that the P1 substrate helix and J8/7 single stranded segment form an extended minor groove triple helix within the catalytic core of the ribozyme. Because each triple in the complex is mediated by at least one 2'-OH group, this substrate recognition triplex is unique to RNA and is fundamentally different from major groove homopurine-homopyrimidine triplexes. We have incorporated these biochemical data into a structural model of the ribozyme core that explains how the J8/7 strand organizes several helices within this complex RNA tertiary structure.
四膜虫I组核酶要实现催化作用，需要几个双螺旋和单链RNA元件紧密堆积。这些堆积相互作用的化学基础很大程度上尚不清楚。利用核苷酸类似物干扰抑制（NAIS）技术，我们证明P1底物螺旋和J8/7单链片段在核酶的催化核心内形成了一个延伸的小沟三链螺旋。由于复合物中的每个三链体至少由一个2'-OH基团介导，这种底物识别三链体是RNA特有的，与大沟同型嘌呤-同型嘧啶三链体有根本区别。我们已将这些生化数据纳入核酶核心的结构模型，该模型解释了J8/7链如何在这种复杂的RNA三级结构中组织几个螺旋。
