Activity of the hammerhead ribozyme upon inversion of the stereocenters for the guanosine 2'-hydroxyls.
Activity of the hammerhead ribozyme upon inversion of the stereocenters for the guanosine 2'-hydroxyls.
复制标题
鸟苷 2-羟基立构中心反转后锤头核酶的活性。
DOI：
10.1021/bi00250a045
复制
发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
McLaughlin,LW
中科院分区：
文献类型：
--
作者：
Fu,DJ;Rajur,SB;McLaughlin,LW
Revised Manuscript Received September 6, 1994® abstract: Two guanosine 2'-hydroxyls in the hammerhead RNA complex at positions G5 and G8 are critical for efficient cleavage by this RNA catalyst. These two functional groups are likely involved in the binding of the metal cofactor, or they are involved in specific interresidue hydrogen-bonding interactions. The importance of the stereochemical positioning of both critical 2'-hydroxyls was investigated by comparing the cleavage rates of three arabinosylguanine-substituted complexes (in which the positions of specific guanosine 2'-hydroxyls were stereochemically altered by inverting the C2'stereocenter) with that of the nativecomplex, as well as with the rates of the dG-and dFG-substituted complexes [in which the 2'-hydroxyls are absent as the result of substitution by 2'-deoxyguanosine (dG) or 2'-deoxy-2'-fluoroguanosine (dFG)]. The G5araGand G8araG complexes exhibit dramatically different cleavage rates. The G5araG complex is essentially inactive, at least105-fold slower than the native complex. RNA cleavage by this analogue ribozyme is also 1000-fold slower than cleavage by either the G5dG or the G5dFG ribozyme, both of whichlack the 2'-hydroxyl at G5. By comparison, catalytic efficiency of the G8araG complex as expressed by kc JKm is comparable with that of the nativecomplex and some 2 orders of magnitude more active than either the G8dG or the G8dFG complex.The hammerhead RNAs represent a small class of catalyti-cally active nucleicacid complexes capable of accelerating the transesterification of a specific phosphodiester residue [for a review, see Bruening (1989)]. The active complex consists of three helical stems and a series of eleven conserved nucleoside residues comprising the core region (see Figure 1). Nine of the conserved residues are nominally single-stranded, but they presumably fold into a specific structure in order to bind and/or optimally position the metal cofactor (Mg2+ or Mn2+) required for catalytic activity
