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Publication Abstract from PubMed

Two types of glycyl-tRNA synthetase (GlyRS) are known, the alpha2 and the alpha2beta2 GlyRSs. Both types of synthetase employ a class II catalytic domain to aminoacylate tRNAGly. In plastids and some bacteria, the alpha and beta subunits are fused and are designated as (alphabeta)2 GlyRSs. While the tRNA recognition and aminoacylation mechanisms are well understood for alpha2 GlyRSs, little is known about the mechanisms for alpha2beta2/(alphabeta)2 GlyRSs. Here we describe structures of the (alphabeta)2 GlyRS from Oryza sativa chloroplast by itself and in complex with cognate tRNAGly. The set of structures reveals that the U-shaped beta half of the synthetase selects the tRNA in a two-step manner. In the first step, the synthetase engages the elbow and the anticodon base C35 of the tRNA. In the second step, the tRNA has rotated approximately 9 degrees toward the catalytic centre. The synthetase probes the tRNA for the presence of anticodon base C36 and discriminator base C73. This intricate mechanism enables the tRNA to access the active site of the synthetase from a direction opposite to that of most other class II synthetases.

Structural basis of a two-step tRNA recognition mechanism for plastid glycyl-tRNA synthetase.,Yu Z, Wu Z, Li Y, Hao Q, Cao X, Blaha GM, Lin J, Lu G Nucleic Acids Res. 2023 May 8;51(8):4000-4011. doi: 10.1093/nar/gkad144. PMID:36912079^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.