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Editing Domain (2 nd Sieve) Catalytic Domain (1 st Sieve) Anticodon Binding Domain C-Terminal Coiled-Coil Domain 862 amino acids 25 -helices 30 -strands Overall Structure

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Function Aminoacyl tRNA synthetases are enzymes that catalyze the esterification of a specific amino acid to a compatible cognate tRNA to form an aminoacyl- tRNA Class I vs. Class II: 2-OH, then 3-OH Directly to 3-OH

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Double-Sieve Concept

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Aminoacylation Site Interactions Hydrophobic Pocket Pro 41 Pro 42 Asn 44 Ile 491 Trp 491 Trp 456 Asp 81

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KMSKS Loop Met 529

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Editing Domain Interactions Thr 214 Tyr 337 Phe 264 Leu 269 Leu 278 Glu 261 Glu 281

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Editing Hydrophilic Pocket

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Anticodon Binding Domain *nucleotides are in green, amino acids are in yellow

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Kinetics for C-term. Domain o phosphates on A20 & A21 interact through salt bridges with Arg818 and Arg843 o G19 & C56 crucial of correct positioning of 3 CCA end of tRNA into aminoacylation catalytic site

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References 1.Fukai, S.; Nureki, O.; Sekine, S.; Shimada, A.; Tao, J.; Vassylyev, D.G.; Yokoyama, S. Structural Basis for Double-Sieve Discrimination of L-Valine from L-Isoleucine and L- Threonine by the Complex of tRNA Val and Valyl-tRNA Synthetase. Cell 2000, 103, 793-803. 2.Fukai, S.; Nureki, O.; Sekine, S.; Shimada, A.; Vassylyev, D.G.; Yogoyama, S. Mechanism of molecular interactions for tRNA Val recognition by valyl-tRNA synthetase. RNA 2003, 9, 100- 111. 3.Fukunaga, R.; Yokoyama, S. Structural Basis for Non-cognate Amino Acid Discrimination by the Valyl-tRNA Synthetase Editing Domain. J. Bio. Chem. 2005, 280 (33), 29937-29945. 4.Liu, M.; Chu, W.; Liu, J.C.H.; Horowitz, J. Role of acceptor stem conformation in tRNA Val recognition by its cognate synthetase. Nucleic Acids Res. 1997, 25, 4883-4890.