Convergent transcripts of the yeast PRP38-SMD1 locus encode two essential splicing factors, including the D1 core polypeptide of small nuclear ribonucleoprotein particles.
Convergent transcripts of the yeast PRP38-SMD1 locus encode two essential splicing factors, including the D1 core polypeptide of small nuclear ribonucleoprotein particles.
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DOI：
10.1073/pnas.90.3.848
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发表时间：
1993-02
影响因子：
11.1
通讯作者：
Brian C. Rymond
中科院分区：
文献类型：
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作者：
Brian C. Rymond
酿酒酵母的PRP38基因是从Pre-mRNA中删除内含子序列所必需的，也是维持最高水平的U6小核RNA(SnRNA)所必需的。本文报道了一个与PRP38功能相关的基因SMD1的鉴定，该基因位于PRP38的3‘端。PRP38和SMD1转录单位以不寻常的“尾对尾”排列配置，其各自的开放阅读框终止于共同的6-bp区域的相反链上。预测的SMD1多肽Smd1p与人类小核核糖核蛋白颗粒的D1蛋白有40%的同源性。实验诱导的Smd1p的耗尽阻止了剪接的第一步，并导致生长停滞。此外，随着Smd1p的耗尽，三甲基鸟苷封顶的剪接体SnRNA、U1、U2、U4和U5的水平下降，但对Prp38p敏感的U6 SnRNA的水平没有下降。在没有SMD1表达的情况下持续存在的SnRNAs的帽子结构似乎是特殊的，因为它们很难被抗三甲基鸟苷抗体识别。这些数据证明Smd1p是细胞剪接设备的必要组件，也是SnRNA成熟和稳定的因素。
The PRP38 gene of Saccharomyces cerevisiae is necessary for the excision of intron sequences from pre-mRNA and required for the maintenance of maximal levels of U6 small nuclear RNA (snRNA). This report describes the identification of a gene of related function, SMD1, located immediately 3' to PRP38. The PRP38 and SMD1 transcription units are configured in an unusual "tail-to-tail" arrangement with their respective open reading frames terminating on opposite strands of a common 6-bp region. The predicted SMD1 polypeptide, Smd1p, is 40% identical to the D1 protein of human small nuclear ribonucleoprotein particles. Experimentally induced depletion of Smd1p blocks the first step of splicing and results in growth arrest. In addition, the levels of the trimethylguanosine-capped spliceosomal snRNAs, U1, U2, U4, and U5, but not the Prp38p-sensitive U6 snRNA, decrease in response to Smd1p depletion. The cap structures of snRNAs persisting in the absence of SMD1 expression appear to be peculiar, as they are poorly recognized by an anti-trimethylguanosine antibody. These data establish Smd1p as a required component of the cellular splicing apparatus and a factor in snRNA maturation and stability.