Singly and bifurcated hydrogen-bonded base-pairs in tRNA anticodon hairpins and ribozymes
Singly and bifurcated hydrogen-bonded base-pairs in tRNA anticodon hairpins and ribozymes
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DOI：
10.1006/jmbi.1999.3080
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发表时间：
1999-09-24
影响因子：
5.6
通讯作者：
Westhof, E
中科院分区：
文献类型：
--
作者：
Auffinger, P;Westhof, E
tRNA反密码子环通常由7个核苷酸组成，参与蛋白质和RNA片段的许多识别过程。我们已经调查的性质和可能的相互作用的第一个（32）和最后（38）残基的循环的基础上，可用的序列和晶体结构。数据表明，位于茎/环连接处的残基32和38之间的分叉氢键相互作用的保守性。这种相互作用导致形成非规范碱基对，其保存在已知的tRNA/合成酶复合物的晶体结构中。在tRNA和tDNA序列中，32.38个相对位置中的93%可以分配给两个等排碱基对家族，一个具有大的（86%）群体，另一个具有小得多的（7%）群体。其余的（7%）反对派已被分配到第三个家庭，由于缺乏证据将他们分配到前两组。在所有家族中，Y32.R38碱基对在反转时不是等排的（如剪切的G. A或摆动的G.U对），这解释了嘧啶在位置32处的强保守性。因此，32.38相互作用将反密码子环的序列特征延伸超过位置33处的保守U形转弯和位置37处的通常修饰的嘌呤。与其他含有单氢键碱基对和U形转弯的环的比较表明，32.38对可能参与了核糖体RNA组分中具有残基的碱基三联体的形成。还观察到两种核酶（锤头和leadzyme）的晶体结构在切割位点呈现相似的碱基对。(C)北京：科学出版社.
The tRNA anticodon loops always comprise seven nucleotides and is involved in many recognition processes with proteins and RNA Fragments. We have investigated the nature and the possible interactions between the first (32) and last (38) residues of the loop on the basis of the available sequences and crystal structures. The data demonstrate the conservation of a bifurcated hydrogen bond interaction between residues 32 and 38, located at the stem/loop junction. This interaction leads to the formation of a non-canonical base-pair which is preserved in the known crystal structures of tRNA/synthetase complexes. Among the tRNA and tDNA sequences, 93% of the 32.38 oppositions can be assigned to two families of isosteric base-pairs, one with a large (86 %) and the other with a much smaller (7 %) population. The remainder (7 %) of the oppositions have been assigned to a third family due to the lack of evidence for assigning them into the first two sets. In all families, the Y32.R38 base-pairs are not isosteric upon reversal (like the sheared G.A or wobble G.U pairs), explaining the strong conservation of a pyrimidine at position 32. Thus, the 32.38 interaction extends the sequence signature of the anticodon loop beyond the conserved U-turn at position 33 and the usually modified purine at position 37. A comparison with other loops containing both a singly hydrogen-bonded base-pair and a U-turn suggests that the 32.38 pair could be involved in the formation of a base triple with a residue in a ribosomal RNA component. It is also observed that two crystal structures of ribozymes (hammerhead and leadzyme) present similar base-pairs at the cleavage site. (C) 1999 Academic Press.