The two similarly expressed genes encoding U3 snRNA in Schizosaccharomyces pombe lack introns.
The two similarly expressed genes encoding U3 snRNA in Schizosaccharomyces pombe lack introns.
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DOI：
10.1093/oxfordjournals.molbev.a040721
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发表时间：
1992-03
影响因子：
10.7
通讯作者：
D. Selinger;G. Porter;P. Brennwald;J. Wise
中科院分区：
文献类型：
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作者：
D. Selinger;G. Porter;P. Brennwald;J. Wise
最近从萌芽酵母中分离的两个编码U3小核RNA(SnRNA)的基因都被前mRNA剪接机器移除的内含子打断。我们之前描述了来自裂殖酵母的两个U3基因之一。在本工作中，鉴定了第二个编码序列，并通过直接RNA序列分析表明，该菌的U3A和U3B基因都不包含插入序列。我们的数据也表明，正如预期的那样，这两个RNA表现出很好的一级和二级结构保守性。这些相似之处不太可能是最近的基因复制或转换事件的结果，因为U3A和U3B基因两侧的DNA序列已经发生了实质性的分化。一个值得注意的例外是一个19个碱基对的区块，以转录起始点上游的36个核苷酸为中心，其中两个座位在15个位置匹配；这个基序可能代表RNA聚合酶II上游调控元件，因为相关序列在分裂酵母U1、U2、U4和U5 SnRNA基因之前被发现。U3A和U3B基因下游的一个短的保守序列的意义尚不清楚，因为在S.pombe中没有发现它与其他SnRNA编码序列的3‘。与我们先前对裂殖酵母U3A和其他低等真核生物U3同源物的研究一样，U3B RNA的5‘三分之一可以折叠成双发夹结构。对裂解酵母U3A和U3B的定量检测表明，与酿酒酵母中的SnR17A和B相反，这些RNA的积累水平相似。
Both genes encoding U3 small nuclear RNA (snRNA) from the budding yeast Saccharomyces cerevisiae were recently shown to be interrupted by introns of the type removed by the pre-mRNA splicing machinery. We previously described one of the two U3 genes from the fission yeast Schizosaccharomyces pombe. In the present work, the second S. pombe U3 coding sequence was identified, and direct RNA sequence analysis was used to show that neither the U3A nor the U3B gene from this organism contains an intervening sequence. Our data also demonstrate that, as expected, the two RNAs exhibit great primary- and secondary-structure conservation. These similarities are not likely to be the result of a recent gene duplication or conversion event, because the DNA sequences flanking the U3A and U3B genes have diverged substantially. A notable exception is a 19-bp block, centered 36 nucleotides upstream from the transcriptional start site, in which the two loci match in 15 positions; this motif may represent an RNA polymerase II upstream regulatory element, because related sequences are found preceding fission yeast U1, U2, U4, and U5 snRNA genes. The significance of a short conserved sequence just downstream of the U3A and U3B genes is unknown, as it is not found 3' to other snRNA coding sequences in S. pombe. The 5' one-third of U3B RNA can be folded into a dual hairpin structure, as we previously proposed for Schizosaccharomyces pombe U3A and for other lower eukaryotic U3 homologues. Quantitation of fission yeast U3A and U3B indicates that, in contrast to snR17A and B in Saccharomyces cerevisiae, these RNAs accumulate to similar levels.