The cover shows a structural model of the mutated E. coli tyrosyl-tRNA synthetase (F130S) bound to azatyrosyl adenylate. The side chains of Asp¹⁸² and Ser¹³⁰ are shown in orange, -helices in purple, and -sheets in yellow. In comparison to the wild type enzyme, this mutant displays an increased K_m value for tyrosyl adenylate, while maintaining a similar K_m for azatyrosyl adenylate. Details can be found in the article by Hamano-Takaku et al., pages 40324-40328.40324.