Jarmolowski A, Zagorski J, Li H V, Fournier M J
Department of Biochemistry, Lederle Graduate Research Center, University of Massachusetts, Amherst 01003.
EMBO J. 1990 Dec;9(13):4503-9. doi: 10.1002/j.1460-2075.1990.tb07901.x.
The U14 RNA of Saccharomyces cerevisiae is a small nucleolar RNA (snoRNA) required for normal production of 18S rRNA. Depletion of U14 results in impaired processing of pre-rRNA, deficiency in 18S-containing intermediates and marked under-accumulation of mature 18S RNA. The present report describes results of functional mapping of U14, by a variety of mutagenic approaches. Special attention was directed at assessing the importance of sequence elements conserved between yeast and mouse U14 as well as other snoRNA species. Functionality was assessed in a test strain containing a galactose dependent U14 gene. The results show portions of three U14 conserved regions to be required for U14 accumulation or function. These regions include bases in: (i) the 5'-proximal box C region, (ii) the 3'-distal box D region, and (iii) a 13 base domain complementary to 18S rRNA. Point and multi-base substitution mutations in the snoRNA conserved box C and box D regions prevent U14 accumulation. Mutations in the essential 18S related domain do not effect U14 levels, but do disrupt synthesis of 18S RNA, indicating that this region is required for function. Taken together, the results suggest that the box C and box D regions influence U14 expression or stability and that U14 function might involve direct interaction with 18S RNA.
酿酒酵母的U14 RNA是一种小核仁RNA（snoRNA），是正常产生18S rRNA所必需的。U14的缺失会导致前体rRNA加工受损、含18S中间体缺乏以及成熟18S RNA明显积累不足。本报告描述了通过多种诱变方法对U14进行功能定位的结果。特别关注评估酵母和小鼠U14以及其他snoRNA物种之间保守的序列元件的重要性。在含有半乳糖依赖性U14基因的测试菌株中评估功能。结果表明，U14积累或功能需要三个U14保守区域的部分。这些区域包括：（i）5'-近端盒C区域中的碱基，（ii）3'-远端盒D区域中的碱基，以及（iii）与18S rRNA互补的13个碱基结构域。snoRNA保守盒C和盒D区域中的点突变和多碱基取代突变会阻止U14积累。必需的18S相关结构域中的突变不影响U14水平，但会破坏18S RNA的合成，表明该区域是功能所必需的。综合来看，结果表明盒C和盒D区域影响U14的表达或稳定性，并且U14的功能可能涉及与18S RNA的直接相互作用。
