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Structure of the N-terminal extension of human aspartyl-tRNA synthetase: implications for its biological function.

Int. J. Biochem. Cell Biol.2003 Nov;35(11):1548-57
Hae-Kap Cheong 1 , Jin-Young Park , Eun-Hee Kim , Chulhyun Lee , Sunghoon Kim , Youngsoo Kim , Byong-Seok Choi , Chaejoon Cheong
Hae-Kap Cheong 1 , Jin-Young Park , Eun-Hee Kim , Chulhyun Lee , Sunghoon Kim , Youngsoo Kim , Byong-Seok Choi , Chaejoon Cheong
+ et al

[No authors listed]

Author information
  • 1 Magnetic Resonance Team, Korea Basic Science Institute, Daejeon 305-333, South Korea. cheong@kbsi.re.kr

摘要


Human aspartyl-tRNA synthetase (hDRS) contains an extension at the N-terminus, which is involved in the transfer of Asp-tRNA to elongation factor alpha1 (EF1alpha). The structure of the N-terminal extension is critical to its function. Conformational studies on the synthetic, 21-residue N-terminal extension peptide (Thr5-Lys25) of human aspartyl-tRNA synthetase using 1H nuclear magnetic resonance (NMR) spectroscopy, showed that the C-terminus adopts a regular alpha-helix with amphiphilicity, while the N-terminus shows a less-ordered structure with a flexible beta-turn. The observed characteristics suggest a structural switch model, such that when the tRNA is in the stretched conformation, the peptide reduces the rate of dissociation of Asp-tRNA from human aspartyl-tRNA synthetase, and provides enough time for elongation factor 1alpha to interact with the Asp-tRNA. Following Asp-tRNA transfer to EF1alpha, the peptide assumes the folded conformation. The structural switch model supports the direct transfer mechanism.