Download MendeleyE. coli elongation factor Tu bound to a GTP analogue displays an open conformation equivalent to the GDP-bound form.
Johansen, J.S., Kavaliauskas, D., Pfeil, S.H., Blaise, M., Cooperman, B.S., Goldman, Y.E., Thirup, S.S., Knudsen, C.R.(2018) Nucleic Acids Res 46: 8641-8650
- PubMed: 30107565
- DOI: https://doi.org/10.1093/nar/gky697
- Primary Citation of Related Structures:
6EZE - PubMed Abstract:
According to the traditional view, GTPases act as molecular switches, which cycle between distinct 'on' and 'off' conformations bound to GTP and GDP, respectively. Translation elongation factor EF-Tu is a GTPase essential for prokaryotic protein synthesis. In its GTP-bound form, EF-Tu delivers aminoacylated tRNAs to the ribosome as a ternary complex. GTP hydrolysis is thought to cause the release of EF-Tu from aminoacyl-tRNA and the ribosome due to a dramatic conformational change following Pi release. Here, the crystal structure of Escherichia coli EF-Tu in complex with a non-hydrolysable GTP analogue (GDPNP) has been determined. Remarkably, the overall conformation of EF-Tu·GDPNP displays the classical, open GDP-bound conformation. This is in accordance with an emerging view that the identity of the bound guanine nucleotide is not 'locking' the GTPase in a fixed conformation. Using a single-molecule approach, the conformational dynamics of various ligand-bound forms of EF-Tu were probed in solution by fluorescence resonance energy transfer. The results suggest that EF-Tu, free in solution, may sample a wider set of conformations than the structurally well-defined GTP- and GDP-forms known from previous X-ray crystallographic studies. Only upon binding, as a ternary complex, to the mRNA-programmed ribosome, is the well-known, closed GTP-bound conformation, observed.
Organizational Affiliation:
Department of Molecular Biology & Genetics, University of Aarhus, Gustav Wieds Vej 10 C, DK-8000 Aarhus C, Denmark.
