Strobel S A, Cech T R
Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA.
Nat Struct Biol. 1994 Jan;1(1):13-7. doi: 10.1038/nsb0194-13.
RNA cleavage by the Tetrahymena ribozyme requires recognition of the reaction-site helix by the catalytic apparatus. This binding can occur in several registers, each of which results in reaction at a different nucleotide in the helix. We now identify commensurate sets of 2'-hydroxyl interactions on both strands of the reaction-site helix that account for its translocation into alternative binding registers. These results indicate that the ribozyme has a relatively rigid substrate-binding pocket into which the helix can bind in different alignments. A similar mechanism of reaction site recognition is proposed to occur during intron circularization and ribozyme polymerase activity. Translocation of the reaction site duplex provides an example of structural heterogeneity in packing of helices during the tertiary folding of RNA.
嗜热四膜虫核酶进行RNA切割需要催化装置识别反应位点螺旋。这种结合可以在几种不同的配对方式下发生，每种方式都会导致螺旋中不同核苷酸处发生反应。我们现在确定了反应位点螺旋两条链上相对应的2'-羟基相互作用，这些相互作用解释了该螺旋如何转移到不同的结合配对方式中。这些结果表明，核酶具有一个相对刚性的底物结合口袋，螺旋可以以不同的排列方式结合到其中。有人提出，在内含子环化和核酶聚合酶活性过程中会发生类似的反应位点识别机制。反应位点双链体的转移为RNA三级折叠过程中螺旋堆积的结构异质性提供了一个例子。
