Sequential magnesium binding facilitates lysyl-tRNA synthetase to recognize ATP
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Updated: Aug 14, 2025

A Novel Saturation Mutagenesis Approach: Single Step Characterization of Regulatory Protein Binding Sites in RNA Using Phosphorothioates
Published on: August 21, 2018
Zhoufei Hei1,2, Pengfei Fang1,2
1School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub-lane Xiangshan, Hangzhou, 310024, China.
Abstract:
Aminoacyl-tRNA synthetases (aaRSs) catalyze the ligation of amino acids to cognate tRNAs by consuming one molecule of ATP. Magnesium is essential for the enzymes' activity. Certain class II aaRSs, such as lysyl-tRNA synthetase (LysRS) and seryl-tRNA synthetase (SerRS), recognize ATP together with three magnesium ions in the active site. The detailed role of how these magnesium ions facilitate the ATP recognition by the enzyme is unclear. Here, we report analyses of a crystal structure of human LysRS, in which the two enzymatic pockets of the LysRS dimer are in different states. One pocket is vacant of ATP, and the other is in an intermediate state of ATP recognition. Interestingly, only one magnesium ion instead of three is bound in both states. Compared with our previously solved LysRS structures, we proposed the order of binding for the three magnesium ions. These structures also reveal multiple intermediate ATP-bound states during the amino acid activation reaction, providing critical insights into the mechanisms of the magnesium-dependent enzyme activity of class II aaRSs.
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