Brenner S, Corrochano L M
Department of Medicine, University of Cambridge School of Clinical Medicine, United Kingdom.
Proc Natl Acad Sci U S A. 1996 Aug 6;93(16):8485-9. doi: 10.1073/pnas.93.16.8485.
We have characterized hisS, the gene encoding the histidyl-tRNA synthetase (HisRS) from the tetraodontoid fish Fugu rubripes. The hisS gene is about 3.5 kbp long and contains 13 exons and 12 introns of 172 bp, on average. The Fugu hisS gene encodes a putative protein of 519 amino acids with the three motifs identified as signatures of class 2 aminoacyl-tRNA synthetases. A model for the shifting of intron 8 between Fugu and hamster is proposed based on the successive appearance of a cryptic splicing site followed by an insertion mutation that created a new acceptor site. In addition, sequence comparisons suggest that the hisS gene has undergone a translocation through the first intron. As a result, the Fugu HisRS has an N-terminal sequence markedly different from that in the human and hamster enzymes. We propose that similar events have been responsible for variations at the N-terminal end of other aminoacyl-tRNA synthetases. Our analysis suggests that this involves exchanges through introns of two exons encoding an ancestral 32-amino acid motif.
我们已经对来自河豚（Fugu rubripes）的组氨酰 - tRNA合成酶（HisRS）编码基因hisS进行了表征。hisS基因长度约为3.5千碱基对，平均包含13个外显子和12个长度为172碱基对的内含子。河豚hisS基因编码一个由519个氨基酸组成的推定蛋白，该蛋白具有被鉴定为2类氨酰 - tRNA合成酶特征的三个基序。基于一个隐蔽剪接位点的连续出现，随后是一个产生新受体位点的插入突变，提出了河豚和仓鼠之间第8号内含子移位的模型。此外，序列比较表明hisS基因通过第一个内含子发生了易位。结果，河豚HisRS的N端序列与人类和仓鼠酶的N端序列明显不同。我们提出，类似事件导致了其他氨酰 - tRNA合成酶N端的变异。我们的分析表明，这涉及通过内含子交换两个编码一个32个氨基酸的祖先基序的外显子。
