The binding mode of orphan glycyl-tRNA synthetase with tRNA supports the synthetase classification and reveals large domain movements

Sci Adv. 2023 Feb 10;9(6):eadf1027. doi: 10.1126/sciadv.adf1027. Epub 2023 Feb 8.

Abstract

As a class of essential enzymes in protein translation, aminoacyl-transfer RNA (tRNA) synthetases (aaRSs) are organized into two classes of 10 enzymes each, based on two conserved active site architectures. The (αβ)2 glycyl-tRNA synthetase (GlyRS) in many bacteria is an orphan aaRS whose sequence and unprecedented X-shaped structure are distinct from those of all other aaRSs, including many other bacterial and all eukaryotic GlyRSs. Here, we report a cocrystal structure to elucidate how the orphan GlyRS kingdom specifically recognizes its substrate tRNA. This structure is sharply different from those of other aaRS-tRNA complexes but conforms to the clash-free, cross-class aaRS-tRNA docking found with conventional structures and reinforces the class-reconstruction paradigm. In addition, noteworthy, the X shape of orphan GlyRS is condensed with the largest known spatial rearrangement needed by aaRSs to capture tRNAs, which suggests potential nonactive site targets for aaRS-directed antibiotics, instead of less differentiated hard-to-drug active site locations.

MeSH terms

  • Amino Acyl-tRNA Synthetases* / chemistry
  • Amino Acyl-tRNA Synthetases* / genetics
  • Amino Acyl-tRNA Synthetases* / metabolism
  • Catalytic Domain
  • Glycine-tRNA Ligase* / chemistry
  • Glycine-tRNA Ligase* / genetics
  • Glycine-tRNA Ligase* / metabolism
  • Ligases / metabolism
  • RNA, Transfer

Substances

  • Glycine-tRNA Ligase
  • Amino Acyl-tRNA Synthetases
  • Ligases
  • RNA, Transfer