Unexpected abundance of self-splicing introns in the genome of bacteriophage Twort: Introns in multiple genes, a single gene with three introns, and exon skipping by group I ribozymes
Unexpected abundance of self-splicing introns in the genome of bacteriophage Twort: Introns in multiple genes, a single gene with three introns, and exon skipping by group I ribozymes
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DOI：
10.1073/pnas.96.12.7005
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发表时间：
1999-06-08
影响因子：
11.1
通讯作者：
Shub, DA
中科院分区：
文献类型：
--
作者：
Landthaler, M;Shub, DA
对可用GTP标记的RNA的分析表明，在金黄色葡萄球菌噬菌体Twort的基因组中，至少有三个转录类别的基因中存在I类内含子。一个编码142个氨基酸的单一开放阅读框（Orf142）被三个自我剪接的I类内含子中断，这是首个具有多个内含子插入的噬菌体基因的例子。Twort Orf142在感染后15 - 20分钟的一条丰富的信使RNA中编码，并且与形态相关的李斯特菌噬菌体A511的一个晚期基因产物（Orf8）高度相似。orf142中的内含子在体内进行剪接，并且包含IA2亚组中I类内含子的一级序列和二级结构的所有保守特征，其中包括大肠杆菌噬菌体T4以及芽孢杆菌噬菌体β22和SPO1中的内含子。orf142中的内含子I2和I3高度相似，并且它们的内含子插入位点紧密相邻。在这些内含子之间存在具有缺失外显子的转录本，这表明它们可能折叠成一个单一的活性核酶，从而导致可变剪接。或者，在I2之前被切割的5'外显子可能与I3之后的3'外显子进行反式剪接。不管具体机制如何，这些结果展示了一种新的方式，即单个基因可以产生多种信使RNA。
Analysis of RNA that can be labeled with GTP indicates the existence of group I introns in genes of at least three transcriptional classes in the genome of Staphylococcus aureus bacteriophage Twort, A single ORF of 142 amino acids (Orf142) is interrupted by three self-splicing group I introns, providing the first example of a phage gene with multiple intron insertions. Twort Orf142 is encoded in a message that is abundant 15-20 min after infection and is highly similar to a late gene product (Orf8) of the morphologically related Listeria phage A511, The introns in orf142 are spliced in vivo and contain all the conserved features of primary sequence and secondary structure of group I introns in subgroup IA2, which includes the introns in Escherichia call phage T4 and the Bacillus phages beta 22 and SPO1. Introns I2 and I3 in orf142 are highly similar, and their intron insertion sites are closely spaced, The presence of transcripts with a shipped exon between these introns indicates that they may fold into a single active ribozyme resulting in alternative splicing. Alternatively, the cleaved 5' exon preceding I2 may undergo trans splicing to the 3' exon that follows I3. Regardless of the detailed mechanism, these results demonstrate a new means whereby a single gene can give rise to multiple messenger RNAs.