Structure of the ArgRS–GlnRS–AIMP1 complex and its implications for mammalian translation

Significance In higher eukaryotes, aminoacyl-tRNA synthetases (ARSs) are assembled to form a multisynthetase complex (MSC), which plays critical roles in translation and nontranslation functions essential for cell growth and survival of organisms. The MSC complex is comprised of nine different ARSs and three accessary proteins. The crystal structure of the arginyl-tRNA synthetase (ArgRS)–glutaminyl-tRNA synthase–aminoacyl tRNA synthetase complex-interacting multifunctional protein 1 (AIMP1) subcomplex reveals that the N-terminal domains of ArgRS and AIMP1 form an extended coiled-coil structure, which provides a central depot for the assembly of a ternary complex. The stability of the N-terminal helix of ArgRS is critical for its ARS activity and noncanonical function of the subcomplex, explaining the significance of the MSC structure in translation and cellular functions.