title: A model for the interaction of the G3-subdomain of Geobacillus stearothermophilus IF2 with the 30S ribosomal subunit.
abstract: Bacterial translation initiation factor IF2 complexed with GTP binds to the 30S ribosomal subunit, promotes ribosomal binding of fMet-tRNA, and favors the joining of the small and large ribosomal subunits yielding a 70S initiation complex ready to enter the translation elongation phase. Within the IF2 molecule subdomain G3, which is believed to play an important role in the IF2-30S interaction, is positioned between the GTP-binding G2 and the fMet-tRNA binding C-terminal subdomains. In this study the solution structure of subdomain G3 of Geobacillus stearothermophilus IF2 has been elucidated. G3 forms a core structure consisting of two β-sheets with each four anti-parallel strands, followed by a C-terminal α-helix. In line with its role as linker between G3 and subdomain C1, this helix has no well-defined orientation but is endowed with a dynamic nature. The structure of the G3 core is that of a typical OB-fold module, similar to that of the corresponding subdomain of Thermus thermophilus IF2, and to that of other known RNA-binding modules such as IF2-C2, IF1 and subdomains II of elongation factors EF-Tu and EF-G. Structural comparisons have resulted in a model that describes the interaction between IF2-G3 and the 30S ribosomal subunit.
authors.affiliation: Department of Chemistry, NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands.
authors.forename: Ramachandra
authors.initials: R
authors.lastname: Dongre
authors.affiliation: Department of Chemistry, NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands.
authors.forename: Gert E
authors.initials: GE
authors.lastname: Folkers
authors.affiliation: Laboratory of Genetics, Department of Biosciences and Biotechnology, University of Camerino, Italy.
authors.forename: Claudio O
authors.initials: CO
authors.lastname: Gualerzi
authors.affiliation: Department of Chemistry, NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands.
authors.forename: Rolf
authors.initials: R
authors.lastname: Boelens
authors.affiliation: Department of Chemistry, NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Wienk
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001411:Geobacillus stearothermophilus / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D039881:Prokaryotic Initiation Factor-2 / Q000737:chemistry* / Q000378:metabolism; D000072417:Protein Domains; D054680:Ribosome Subunits, Small, Bacterial / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D039881:Prokaryotic Initiation Factor-2
keywords: NMR; bacterial IF2; protein structure; protein synthesis; ribosomal subunits; translation initiation