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Two conformations of a crystalline human tRNA synthetase–tRNA complex: implications for protein synthesis
Author(s) -
Yang XiangLei,
Otero Francella J,
Ewalt Karla L,
Liu Jianming,
Swairjo Manal A,
Köhrer Caroline,
RajBhandary Uttam L,
Skene Robert J,
McRee Duncan E,
Schimmel Paul
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601154
Subject(s) - biology , transfer rna , biochemistry , amino acyl trna synthetases , protein biosynthesis , aminoacyl trna synthetase , genetics , rna , gene
Aminoacylation of tRNA is the first step of protein synthesis. Here, we report the co‐crystal structure of human tryptophanyl‐tRNA synthetase and tRNA Trp . This enzyme is reported to interact directly with elongation factor 1α, which carries charged tRNA to the ribosome. Crystals were generated from a 50/50% mixture of charged and uncharged tRNA Trp . These crystals captured two conformations of the complex, which are nearly identical with respect to the protein and a bound tryptophan. They are distinguished by the way tRNA is bound. In one, uncharged tRNA is bound across the dimer, with anticodon and acceptor stem interacting with separate subunits. In this cross‐dimer tRNA complex, the class I enzyme has a class II‐like tRNA binding mode. This structure accounts for biochemical investigations of human TrpRS, including species‐specific charging. In the other conformation, presumptive aminoacylated tRNA is bound only by the anticodon, the acceptor stem being free and having space to interact precisely with EF‐1α, suggesting that the product of aminoacylation can be directly handed off to EF‐1α for the next step of protein synthesis.