Tyrosyl tRNA Synthetase 2, Mitochondrial (YARS2)

YARS2, deduced 477-amino acid protein contains a 16-amino acid mitochondrial targeting signal and catalytic site motifs characteristic of amino acid tRNA synthetases.The structure shows that the group I intron binds across the 2 subunits of the homodimeric protein with a newly evolved RNA-binding surface distinct from that which binds tyrosine tRNA. This RNA binding surface provides an extended scaffold for the phosphodiester backbone of the conserved catalytic core of the intron RNA, allowing the protein to promote the splicing of a wide variety of group I introns. The group I intron-binding surface includes 3 small insertions and additional structural adaptations relative to nonsplicing bacterial tyrosyl-tRNA synthetases, indicating a multistep adaptation for splicing function.