Murchie A I, Thomson J B, Walter F, Lilley D M
Department of Biochemistry, University of Dundee, United Kingdom.
Mol Cell. 1998 May;1(6):873-81. doi: 10.1016/s1097-2765(00)80086-6.
The hairpin ribozyme is a self-cleaving motif found in the negatives strand of the satellite RNA of some plant viruses. In its natural context, the ribozyme comprises four helices, two of which contain conserved formally unpaired loops, that are adjacent arms of a four-way RNA junction. We show that the arms that would carry these loops are brought close together in the global conformation of the isolated junction. Using fluorescence resonance energy transfer, we demonstrate a two-magnesium ion-dependent conformational transition of the complete ribozyme that brings the loopbearing arms into close physical proximity. The ribozyme is active as a four-way junction, and the rate of cleavage may be modulated by the conformation of the four-way junction.
发夹状核酶是在一些植物病毒的卫星RNA负链中发现的一种自我切割基序。在其自然环境中，核酶由四个螺旋组成，其中两个包含保守的形式上未配对的环，它们是一个四向RNA连接的相邻臂。我们表明，携带这些环的臂在分离的连接的整体构象中彼此靠近。利用荧光共振能量转移，我们证明了完整核酶的一种依赖于两个镁离子的构象转变，该转变使携带环的臂在物理上紧密靠近。核酶作为一个四向连接是有活性的，并且切割速率可能受四向连接构象的调节。
