Pham Yen, Li Li, Kim Aram, Erdogan Ozgun, Weinreb Violetta, Butterfoss Glenn L, Kuhlman Brian, Carter Charles W
Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Mol Cell. 2007 Mar 23;25(6):851-62. doi: 10.1016/j.molcel.2007.02.010.
The emergence of polypeptide catalysts for amino acid activation, the slowest step in protein synthesis, poses a significant puzzle associated with the origin of biology. This problem is compounded as the 20 contemporary aminoacyl-tRNA synthetases belong to two quite distinct families. We describe here the use of protein design to show experimentally that a minimal class I aminoacyl-tRNA synthetase active site might have functioned in the distant past. We deleted the anticodon binding domain from tryptophanyl-tRNA synthetase and fused the discontinuous segments comprising its active site. The resulting 130 residue minimal catalytic domain activates tryptophan. This residual catalytic activity constitutes the first experimental evidence that the conserved class I signature sequences, HIGH and KMSKS, might have arisen in-frame, opposite motifs 2 and 1 from class II, as complementary sense and antisense strands of the same ancestral gene.
用于氨基酸活化（蛋白质合成中最慢的步骤）的多肽催化剂的出现，引发了一个与生物学起源相关的重大谜题。由于20种现代氨酰-tRNA合成酶分属于两个截然不同的家族，这个问题变得更加复杂。我们在此描述了利用蛋白质设计通过实验表明，一个最小的I类氨酰-tRNA合成酶活性位点可能在遥远的过去发挥过作用。我们从色氨酰-tRNA合成酶中删除了反密码子结合结构域，并融合了构成其活性位点的不连续片段。由此产生的130个残基的最小催化结构域可激活色氨酸。这种残留的催化活性构成了首个实验证据，即保守的I类特征序列HIGH和KMSKS可能是以框内形式出现的，与II类的基序2和基序1相反，如同同一个祖先基因的互补有义链和反义链。
