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Updated: May 28, 2026
10:37
Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
Published on: May 10, 2018
Structural transitions of translation initiation factor IF2 upon GDPNP and GDP binding in solution
Louise Carøe Vohlander Rasmussen1, Cristiano Luis Pinto Oliveira, Jan Skov Pedersen
1Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark.
Biochemistry
|October 13, 2011
Summary
Bacterial translation initiation factor IF2 undergoes conformational changes upon nucleotide binding. These structural shifts, observed using SAXS, suggest a cofactor-dependent switching mechanism rather than a classical GTPase model.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Translation initiation factor IF2 (IF2) is crucial for bacterial protein synthesis.
- IF2 functions as a ribosome-dependent GTPase, ensuring accurate initiator tRNA positioning and ribosomal subunit joining.
- The C-terminal domain of IF2 (IF2C) plays a role in these functions.
Purpose of the Study:
- To investigate the structural changes of IF2C upon binding of GDP or GTP analogues.
- To model the structure of IF2C in complex with GDPNP and GDP.
- To elucidate the mechanism of GTPase activity in translation initiation.
Main Methods:
- Small-angle X-ray scattering (SAXS) was used to determine the solution structure of IF2C.
- SAXS data were analyzed to assess conformational changes upon nucleotide binding.
- Structural models of IF2C-nucleotide complexes were generated.
Main Results:
- IF2C exhibited distinct elongated conformations in the presence of GDPNP and GDP.
- Radii of gyration and maximum dimensions indicated significant structural changes.
- SAXS data supported cofactor-dependent conformational switching.
Conclusions:
- The structural transitions of IF2C upon nucleotide binding and hydrolysis challenge the classical GTPase model.
- A model of cofactor-dependent conformational switching is proposed for IF2 function.
- Understanding IF2's mechanism provides insights into bacterial translation regulation.
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