A loop 2 cytidine-stem 1 minor groove interaction as a positive determinant for pseudoknot-stimulated -1 ribosomal frameshifting
A loop 2 cytidine-stem 1 minor groove interaction as a positive determinant for pseudoknot-stimulated -1 ribosomal frameshifting
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DOI：
10.1073/pnas.0506166102
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发表时间：
2005-09-06
影响因子：
11.1
通讯作者：
Giedroc, DP
中科院分区：
文献类型：
--
作者：
Cornish, PV;Hennig, M;Giedroc, DP
RNA 假结刺激 -1 程序化核糖体移码 (- 1 PRF) 的分子决定因素尚不清楚。甘蔗黄叶病毒 (ScYLV) 编码一个 28 nt mRNA 假结，可促进植物黄体病毒 P1（蛋白酶）和 P2（聚合酶）基因之间的 -1 PRF。 ScYLV 假结的溶液结构揭示了一个有序的环 2 (L2)，其表现出 A20 到 C27 在上茎 1 (S1) 的小沟中连续堆叠，而 C25 从三链堆叠中翻转出来。五个连续的三碱基对侧翼位于螺旋连接处，其中 L2、C27 的 3' 核苷酸与 C14-G7 碱基对采用胞苷 27 N3-胞苷 14 2'-OH 氢键相互作用。这种相互作用与甜菜西黄病毒 (BWYV) 相关 mRNA 中的腺苷 N1-2'-OH 相互作用是等排的；然而，ScYLV 和 BWYV mRNA 结构的不同之处在于其详细的 L2-S1 氢键和 L2 堆积相互作用。 ScYLV/BWYV 嵌合假结的功能分析表明，相对于 BWYV 假结 (6 +/- 1%)，ScYLV RNA 刺激更高水平的 -1 PRF (15 +/- 2%)，这种差异主要归因于 L2 的 3' 核苷酸的身份（BWYV 中的 C27 与 A25）。引人注目的是，C27A ScYLV RNA 是一种较差的franeshift刺激剂(2.0%)，并且与野生型假结相比，其稳定性受到类似于1.5 kcal(.)mol(-1) (pH 7.0,37℃)的破坏。这些研究证实，结构相似的假结中最接近螺旋连接处的弱相互作用的精确网络对于设定 mRNA 中的移码效率做出了重要贡献。
The molecular determinants of stimulation of -1 programmed ribosomal frameshifting (- 1 PRF) by RNA pseudoknots are poorly understood. Sugarcane yellow leaf virus (ScYLV) encodes a 28-nt mRNA pseudoknot that promotes -1 PRF between the P1 (protease) and P2 (polymerase) genes in plant luteoviruses. The solution structure of the ScYLV pseudoknot reveals a well ordered loop 2 (L2) that exhibits continuous stacking of A20 through C27 in the minor groove of the upper stem 1 (S1), with C25 flipped out of the triple-stranded stack. Five consecutive triple base pairs flank the helical junction where the 3' nucleotide of L2, C27, adopts a cytidine 27 N3-cytidine 14 2'-OH hydrogen bonding interaction with the C14-G7 base pair. This interaction is isosteric with the adenosine N1-2'-OH interaction in the related mRNA from beet western yellows virus (BWYV); however, the ScYLV and BWYV mRNA structures differ in their detailed L2-S1 hydrogen bonding and L2 stacking interactions. Functional analyses of ScYLV/BWYV chimeric pseudoknots reveal that the ScYLV RNA stimulates a higher level of -1 PRF (15 +/- 2%) relative to the BWYV pseudoknot (6 +/- 1%), a difference traced largely to the identity of the 3' nucleotide of L2 (C27 vs. A25 in BWYV). Strikingly, C27A ScYLV RNA is a poor franeshift stimulator (2.0%) and is destabilized by similar to 1.5 kcal(.)mol(-1) (pH 7.0,37 degrees C) with respect to the wild-type pseudoknot. These studies establish that the precise network of weak interactions nearest the helical junction in structurally similar pseudoknots make an important contribution to setting the frameshift efficiency in mRNAs.