Faculté des Sciences et Technologies, Nancy University, UMR AREMS 7214 CNRS-UHP, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-Lès-Nancy cedex, France.
Nucleic Acids Res. 2011 Dec;39(22):9731-45. doi: 10.1093/nar/gkr675. Epub 2011 Sep 2.
In eukaryotes, U3 snoRNA is essential for pre-rRNA maturation. Its 5'-domain was found to form base pair interactions with the 18S and 5'-ETS parts of the pre-rRNA. In Xenopus laevis, two segments of U3 snoRNA form base-pair interactions with the 5'-ETS region and only one of them is essential to the maturation process. In Saccharomyces cerevisiae, two similar U3 snoRNA-5' ETS interactions are possible; but, the functional importance of only one of them had been tested. Surprisingly, this interaction, which corresponds to the non-essential one in X. laevis, is essential for cell growth and pre-rRNA maturation in yeast. In parallel with [Dutca et al. (2011) The initial U3 snoRNA:pre-rRNA base pairing interaction required for pre-18S rRNA folding revealed by in vivo chemical probing. Nucleic Acids Research, 39, 5164-5180], here we show, that the second possible 11-bp long interaction between the 5' domain of S. cerevisiae U3 snoRNA and the pre-rRNA 5'-ETS region (helix VI) is also essential for pre-rRNA processing and cell growth. Compensatory mutations in one-half of helix VI fully restored cell growth. Only a partial restoration of growth was obtained upon extension of compensatory mutations to the entire helix VI, suggesting sequence requirement for binding of specific proteins. Accordingly, we got strong evidences for a role of segment VI in the association of proteins Mpp10, Imp4 and Imp3.
在真核生物中，U3 snoRNA 对于 pre-rRNA 的成熟是必不可少的。其 5'-结构域被发现与 pre-rRNA 的 18S 和 5'-ETS 部分形成碱基对相互作用。在非洲爪蟾中，U3 snoRNA 的两个片段与 5'-ETS 区域形成碱基对相互作用，只有其中一个片段对成熟过程是必不可少的。在酿酒酵母中，两个类似的 U3 snoRNA-5' ETS 相互作用是可能的；但是，只有其中一个的功能重要性已经得到了测试。令人惊讶的是，这种相互作用对应于非洲爪蟾中非必需的相互作用，对于酵母中的细胞生长和 pre-rRNA 成熟是必不可少的。与 [Dutca 等人（2011）体内化学探测揭示了初始 U3 snoRNA：pre-rRNA 碱基配对相互作用对于 pre-18S rRNA 折叠的重要性。核酸研究，39，5164-5180] 平行，我们在这里表明，酿酒酵母 U3 snoRNA 的 5' 结构域和 pre-rRNA 5'-ETS 区域（螺旋 VI）之间的第二个可能的 11 个碱基长相互作用对于 pre-rRNA 加工和细胞生长也是必不可少的。螺旋 VI 一半的补偿性突变完全恢复了细胞生长。只有当补偿性突变扩展到整个螺旋 VI 时，才能获得生长的部分恢复，这表明特定蛋白质结合的序列要求。相应地，我们得到了强有力的证据表明，片段 VI 在 Mpp10、Imp4 和 Imp3 蛋白的结合中起作用。
