Poly(A) tail addition to the 3' end of a wide range of RNAs is a highly conserved modification that plays a central role in cellular RNA function. Elements for nuclear expression (ENEs) are cis-acting RNA elements that stabilize poly(A) tails by sequestering them in RNA triplex structures. A 2.89-Å resolution crystal structure of a double ENE from a rice hAT transposon mRNA complexed with poly(A)28 reveals multiple modes of interaction with poly(A), including major-groove triple helices, extended minor-groove interactions with RNA double helices, a quintuple-base motif that transitions poly(A) from minor-groove associations to major-groove triple helices, and a poly(A) 3'-end binding pocket. Our findings both expand the repertoire of motifs involved in long-range RNA interactions and provide insights into how polyadenylation can protect an RNA's extreme 3' end.

中文翻译：

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通过 poly(A) 尾 3ʹ-末端结合口袋和其他 poly(A)-RNA 相互作用模式稳定 RNA

Poly(A) 尾部添加到各种 RNA 的 3' 末端是一种高度保守的修饰，在细胞 RNA 功能中起核心作用。核表达元件 (ENE) 是顺式作用的 RNA 元件，通过将 poly(A) 尾巴隔离在 RNA 三链体结构中来稳定它们。来自与 poly(A)28 复合的水稻 hAT 转座子 mRNA 的双 ENE 的 2.89-Å 分辨率晶体结构揭示了与 poly(A) 相互作用的多种模式，包括大槽三螺旋、扩展的小槽与双核 RNA 的相互作用螺旋，一个五元基基序，可将 poly(A) 从小凹槽关联转变为大凹槽三螺旋，以及一个 poly(A) 3' 端结合口袋。