Structural dynamics of bacterial translation initiation factor IF2.
Bacterial translation initiation factor IF2 promotes ribosomal subunit association, recruitment, and binding of fMet-tRNA to the ribosomal P-site and initiation dipeptide formation. Here, we present the solution structures of GDP-bound and apo-IF2-G2 of Bacillus stearothermophilus and provide evidence that this isolated domain binds the 50 S ribosomal subunit and hydrolyzes GTP. Differences between the free and GDP-bound structures of IF2-G2 suggest that domain reorganization within the G2-G3-C1 regions underlies the different structural requirements of IF2 during the initiation process. However, these structural signals are unlikely forwarded from IF2-G2 to the C-terminal fMet-tRNA binding domain (IF2-C2) because the connected IF2-C1 and IF2-C2 modules show completely independent mobility, indicating that the bacterial interdomain connector lacks the rigidity that was found in the archaeal IF2 homolog aIF5B.
Bijvoet Center for Biomolecular Research, NMR Spectroscopy, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Hans
H
Wienk
Evgeny
E
Tishchenko
Riccardo
R
Belardinelli
Simona
S
Tomaselli
Ramachandra
R
Dongre
Roberto
R
Spurio
Gert E
GE
Folkers
Claudio O
CO
Gualerzi
Rolf
R
Boelens
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001411:Geobacillus stearothermophilus; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D039881:Prokaryotic Initiation Factor-2 / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; C503923:GDPNP compound; D039881:Prokaryotic Initiation Factor-2; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate