Backbone Brackets and Arginine Tweezers delineate Class I and Class II aminoacyl tRNA synthetases
Fig 4
Comparison of Backbone Brackets and Arginine Tweezers.
(A) Structural representation of the Backbone Brackets motif interacting with Tryptophanyl-5’AMP ligand in TrpRS (PDB:1r6u chain A). The ligand interaction is mediated by backbone hydrogen bonds (solid blue lines). Residue numbers are given in accordance to the structure of origin. (B) The geometry of the Backbone Brackets motif resembles brackets encircling the ligand. (C) WebLogo [75] representation of the sequence of Backbone Brackets residues (274 and 1361) and three surrounding sequence positions. Residue numbers are given in accordance to the MSA. (D) Structural representation of the Arginine Tweezers motif in interaction with Lysyl-5’AMP ligand in LysRS (PDB:1e1t chain A). Salt bridges (yellow dashed lines) as well as π-cation interactions are established. Residue numbers are given in accordance to the structure of origin. (E) The Arginine Tweezers geometry mimics a pair of tweezers grasping the ligand. (F) Sequence of Arginine Tweezers residues (698 and 1786) and surrounding sequence positions. The Backbone Brackets show nearly no conservation on sequence level since backbone interactions can be established by all amino acids, while the Arginine Tweezers rely on salt bridge interactions, always mediated by two arginines. Residue numbers are given in accordance to the MSA.