U1 snRNA is cleaved by RNase III and processed through an Sm site-dependent pathway.
U1 snRNA is cleaved by RNase III and processed through an Sm site-dependent pathway.
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U1 snRNA 被 RNase III 切割并通过 Sm 位点依赖性途径进行加工。
DOI：
10.1093/nar/27.2.587
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发表时间：
1999
影响因子：
14.9
通讯作者：
Rymond,BC
中科院分区：
文献类型：
--
作者：
Seipelt,RL;Zheng,B;Asuru,A;Rymond,BC
核心snRNP蛋白通过保守的Sm位点（普阿（U）n ≥ 3GPu）与snRNA结合。虽然酵母U1 snRNA有三个匹配的Sm共识，U1 3 ′-末端的Sm位点被发现是必要的和足够的U1功能。该位点的突变抑制前体mRNA剪接，阻断细胞分裂，并导致两种3 ′-延伸形式的U1 snRNA的积累。具有Sm位点突变的细胞缺乏成熟的U1 RNA（U1 α），但具有少量的多聚腺苷酸种类U1 γ和突出的非多聚腺苷酸种类U1 β。在离体条件下，合成的U1前体在离体条件下可被Rnt1p（RNase III）切割，切割位置非常靠近U1 β 3 ′-端。我们认为U1 β是Rnt1p裂解的中间体，U1成熟为U1 α形式是通过Sm敏感步骤发生的。有趣的是，U1 α和第二个更长的RNA U1 ε在anrnt 1突变株中产生。这些结果表明，酵母U1 snRNA加工可能通过Rnt1p依赖和Rnt1p独立的途径，这两种途径都需要一个功能性Sm位点的最终snRNA成熟。
Core snRNP proteins bind snRNA through the conserved Sm site, PuA(U)n≥3GPu. While yeast U1 snRNA has three matches to the Sm consensus, the U1 3′-terminal Sm site was found to be both necessary and sufficient for U1 function. Mutation of this site inhibited pre-mRNA splicing, blocked cell division and resulted in the accumulation of two 3′-extended forms of the U1 snRNA. Cells which harbor the Sm site mutation lack mature U1 RNA (U1α) but have a minor polyadenylated species, U1γ, and a prominent, non-polyadenylated species, U1β. Metabolic depletion of the essential Sm core protein, Smd1p, also resulted in the increased accumulation of U1β and U1γ.In vitro, synthetic U1 precursors were cleaved by Rnt1p (RNase III) very near the U1β 3′-end observedin vivo. We propose that U1β is an Rnt1p-cleaved intermediate and that U1 maturation to the U1α form occurs through an Sm-sensitive step. Interestingly, both U1α and a second, much longer RNA, U1ε, were produced in anrnt1mutant strain. These results suggest that yeast U1 snRNA processing may progress through Rnt1p-dependent and Rnt1pindependent pathways, both of which require a functional Sm site for final snRNA maturation.