Novel function of tyrosyl-and tryptophanyl-tRNA synthetases

人类色氨酸- trna合成酶（TrpRS）催化tRNATrp的氨基酰化。人类trpr以两种形式存在：主要形式是全长蛋白和截断形式（迷你trpr）。人类的迷你型，而不是全长型，trpr具有血管抑制活性。在本研究中，我搜索了两种蛋白之间的构象差异，发现两种蛋白之间Cys62周围的分子环境存在显著差异。之前，我证明了Zn2+或血红素与人类trpr的结合会刺激其氨基酰化活性。在本研究中，牛和小鼠的trprs被发现无论是否存在Zn2+或血红素都具有组成性活性。诱变实验表明，人类H130R突变体具有组成性活性，牛R135H、E438A双突变体与Zn2+或血红素结合，增强其氨基酰化活性，与人类野生型trpr一样。

Human tryptophanyl-tRNA synthetase(TrpRS) catalyzes the aminoacylation of tRNATrp. Human TrpRS exists in two forms : a major form that is the full-length protein and a truncated form(mini TrpRS). Human mini, but not full-length, TrpRS has angiostatic activity. In the present study, I searched for conformational differences between the two proteins and showed that the molecular environment around Cys62 is significantly different between the two proteins. Previously, I demonstrated that binding of Zn2+or heme to human TrpRS stimulates its aminoacylation activity. In the present study, bovine and mouse TrpRSs were found to be constitutively active regardless of the presence of Zn2+or heme. Mutagenesis experiments demonstrated that the human H130R mutant is constitutively active and that the bovine R135H, E438A double mutant binds with Zn2+or heme to enhance its aminoacylation activity as does human wild-type TrpRS.