Ohki Yasushi, Ikawa Yoshiya, Shiraishi Hideaki, Inoue Tan
Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
Genes Cells. 2002 Aug;7(8):851-60. doi: 10.1046/j.1365-2443.2002.00567.x.
The Tetrahymena group I ribozyme folds into a complex three-dimensional structure for performing catalytic reactions. The catalysis depends on its catalytic core consisting of two helical domains, P4-P6 and P3-P7, connected by single stranded regions. In the folding process, most of this ribozyme folds in a hierarchical manner in which a kinetically stable intermediate determines the overall folding rate.
Although the nature of this intermediate has not yet been elucidated, a mispaired P3 stem (alt-P3) appears a likely candidate. To examine the effects of the alt-P3 structure on the kinetic and thermodynamic properties of the active structure of the ribozyme or its P3-P7 domain formation, we prepared and analysed variant ribozymes in which relative stabilities of the original P3 and alt-P3 structure were altered systematically.
The results indicate that the alt-P3 structure is not the major rate-limiting factor in the folding process.
嗜热四膜虫I组核酶折叠成复杂的三维结构以进行催化反应。催化作用取决于其由两个螺旋结构域P4 - P6和P3 - P7通过单链区域连接而成的催化核心。在折叠过程中，该核酶的大部分以分级方式折叠，其中动力学稳定的中间体决定了整体折叠速率。
尽管该中间体的性质尚未阐明，但错配的P3茎（alt - P3）似乎是一个可能的候选者。为了研究alt - P3结构对核酶活性结构或其P3 - P7结构域形成的动力学和热力学性质的影响，我们制备并分析了变体核酶，其中原始P3和alt - P3结构的相对稳定性被系统地改变。
结果表明alt - P3结构不是折叠过程中的主要限速因素。
