Human aspartyl-tRNA synthetase (hDRS) contains an extension at the N-terminus, which is involved in the transfer of Asp-tRNA to elongation factor α1 (EF1α). 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 α-helix with amphiphilicity, while the N-terminus shows a less-ordered structure with a flexible β-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 1α to interact with the Asp-tRNA. Following Asp-tRNA transfer to EF1α, the peptide assumes the folded conformation. The structural switch model supports the direct transfer mechanism.
|Number of pages||10|
|Journal||International Journal of Biochemistry and Cell Biology|
|Publication status||Published - 2003 Nov 1|
All Science Journal Classification (ASJC) codes
- Cell Biology