Walker E J, Jeffrey P D
John Curtin School of Medical Research, Australian National University, Canberra.
Protein Seq Data Anal. 1988 Feb;1(3):187-93.
Amino acid sequences of aminoacyl-tRNA synthetases specific for 12 different amino acids have now been published. Differences in origin at the species and organelle level result in 20 distinct sequences being available for comparison. Some of these were compared in small groups as they were determined and, although some homologies were detected, it was generally concluded that there was surprisingly little sequence homology in this functionally related group of enzymes. We have made comparisons of all of the available sequences by using a combination of computer and manual alignment methods and knowledge of the sequences in the Rossmann fold region of methionyl-tRNA synthetase from E. coli and tyrosyl-tRNA synthetase from B. stearothermophilus, enzymes whose three-dimensional structures have been described. It emerges that all of the aminoacyl-tRNA synthetase sequences thus examined show considerable homology with each other over at least parts of this region, some over virtually all of it. We conclude that a great deal more similarity than had previously been suspected exists in these proteins. In particular, the alignments we have made strongly imply the existence of a mononucleotide binding site of the Rossmann fold configuration in all of the synthetases compared.
现已发表了12种不同氨基酸所对应的氨酰-tRNA合成酶的氨基酸序列。物种和细胞器水平上来源的差异导致有20种不同的序列可供比较。其中一些序列在确定后就被分成小组进行比较，虽然检测到了一些同源性，但总体结论是，在这个功能相关的酶类中，序列同源性出奇地低。我们结合计算机和人工比对方法，并利用来自大肠杆菌的甲硫氨酰-tRNA合成酶以及嗜热栖热菌的酪氨酰-tRNA合成酶的罗斯曼折叠区域的序列知识（这两种酶的三维结构已被描述），对所有可用序列进行了比较。结果发现，所有经过检查的氨酰-tRNA合成酶序列在该区域的至少部分区域彼此之间显示出相当高的同源性，有些在几乎整个区域都有同源性。我们得出结论，这些蛋白质之间存在比之前所怀疑的更多的相似性。特别是，我们所做的比对强烈暗示，在所有被比较的合成酶中都存在罗斯曼折叠结构的单核苷酸结合位点。
