MODELING OF THE 3-DIMENSIONAL ARCHITECTURE OF GROUP-I CATALYTIC INTRONS BASED ON COMPARATIVE SEQUENCE-ANALYSIS
MODELING OF THE 3-DIMENSIONAL ARCHITECTURE OF GROUP-I CATALYTIC INTRONS BASED ON COMPARATIVE SEQUENCE-ANALYSIS
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DOI：
10.1016/0022-2836(90)90386-z
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发表时间：
1990-12-05
影响因子：
5.6
通讯作者：
WESTHOF, E
中科院分区：
文献类型：
--
作者：
MICHEL, F;WESTHOF, E
对87个I组自剪接内含子的可用序列进行比对，发现了许多远距离位点之间的协变实例。这些共变中的一些不能归因于历史上的巧合或已知的I组内含子的二级结构，因此，最好的解释是反映了第三级接触。在立体化学模型的帮助下，我们利用这些新的相互作用导出了I组内含子保守核心的三维模型。该模型的两个值得注意的特征是它的极端紧凑，以及所有在进化上最保守的残基恰好聚集在组成核心核酶底物的两个螺旋和结合自剪接所需的鸟苷辅因子的位置。讨论了特定的功能含义，包括底物螺旋被识别为核心的方式，以及在自剪接过程中内含子可能的重排。关于潜在的长程相互作用，重点强调了GAAA或相关的末端环可能识别螺旋小槽中的两个连续的嘌呤。
Alignment of the 87 available sequences of group I self-splicing introns reveals numerous instances of covariation between distant sites. Some of these covariations cannot be ascribed to historical coincidences or the known secondary structure of group I introns, and are, therefore, best explained as reflecting tertiary contacts. With the help of stereochemical modelling, we have taken advantage of these novel interactions to derive a three-dimensional model of the conserved core of group I introns. Two noteworthy features of that model are its extreme compactness and the fact that all of the most evolutionarily conserved residues happen to converge around the two helices that constitute the substrate of the core ribozyme and the site that binds the guanosine cofactor necessary for self-splicing. Specific functional implications are discussed, both with regard to the way the substrate helices are recognized the core and possible rearrangements of the introns during the self-splicing process. Concerning potential long-range interactions, emphasis is put on the possible recognition of two consecutive purines in the minor groove of a helix by a GAAA or related terminal loop.