Modulation of Aminoacylation and Editing Properties of Leucyl-tRNA Synthetase by a Conserved Structural Module*
Modulation of Aminoacylation and Editing Properties of Leucyl-tRNA Synthetase by a Conserved Structural Module*
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DOI：
10.1074/jbc.m115.639492
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
Wei-Qun Yan;Qing Ye;M. Tan;Xi Chen;G. Eriani;E. Wang
中科院分区：
文献类型：
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作者：
Wei-Qun Yan;Qing Ye;M. Tan;Xi Chen;G. Eriani;E. Wang
背景：KMSKS催化环之后的结构模块在大多数I类合成酶中是保守的。结果：该模块有助于氨基酸酰化和编辑亮氨酸- trna合成酶（LeuRS）。结论：该模块以结构和序列依赖的方式影响LeuRS的活性。意义：本工作进一步扩展了LeuRS茎接触褶皱的功能。在Ia类和Ib类氨基酰基trna合成酶中，KMSKS催化环后的保守结构模块呈现α-α-β-α拓扑结构。然而，这一领域的功能却很少受到关注。在这里，我们通过表征来自不同物种的关键残基来描述该模块对亮氨酸- trna合成酶（LeuRSs）的氨基酰化和编辑能力的影响。该结构域第3 α-螺旋上高度保守的碱基突变会破坏LeuRS对tRNALeu反密码子茎的亲和力，从而降低其氨基酰化和编辑活性。α-螺旋上的两个甘氨酸残基有助于大肠杆菌LeuRS （EcLeuRS）的柔韧性、亮氨酸激活和编辑。β-链上的酸性残基增强了EcLeuRS的编辑活性，并感知tRNALeu d环的大小。这些残基的掺入刺激了极简嵌合酶支原体（Mycoplasma mobile LeuRS）的trna依赖性编辑活性，该酶与EcLeuRS的连接多肽1编辑结构域和亮氨酸特异性结构域融合。总之，这些结果揭示了茎接触褶是催化位点和tRNA结合域之间的功能和结构连接体。EcLeuRS茎接触褶结构域与编辑缺陷酶的序列比较表明，该模块的关键残基已经进化出一种适应策略，以遵循LeuRS的编辑功能。
Background: A structural module following the KMSKS catalytic loop is conserved in most class I synthetases. Results: This module contributes to aminoacylation and editing of leucyl-tRNA synthetases (LeuRS). Conclusion: This module affects the activities of LeuRS in both a structure- and sequence-dependent manner. Significance: This work further extends the function of stem-contact fold in LeuRS. A conserved structural module following the KMSKS catalytic loop exhibits α-α-β-α topology in class Ia and Ib aminoacyl-tRNA synthetases. However, the function of this domain has received little attention. Here, we describe the effect this module has on the aminoacylation and editing capacities of leucyl-tRNA synthetases (LeuRSs) by characterizing the key residues from various species. Mutation of highly conserved basic residues on the third α-helix of this domain impairs the affinity of LeuRS for the anticodon stem of tRNALeu, which decreases both aminoacylation and editing activities. Two glycine residues on this α-helix contribute to flexibility, leucine activation, and editing of LeuRS from Escherichia coli (EcLeuRS). Acidic residues on the β-strand enhance the editing activity of EcLeuRS and sense the size of the tRNALeu D-loop. Incorporation of these residues stimulates the tRNA-dependent editing activity of the chimeric minimalist enzyme Mycoplasma mobile LeuRS fused to the connective polypeptide 1 editing domain and leucine-specific domain from EcLeuRS. Together, these results reveal the stem contact-fold to be a functional as well as a structural linker between the catalytic site and the tRNA binding domain. Sequence comparison of the EcLeuRS stem contact-fold domain with editing-deficient enzymes suggests that key residues of this module have evolved an adaptive strategy to follow the editing functions of LeuRS.