H, C and N resonance assignments of translation initiation factor 3 from Pseudomonas aeruginosa.

Translation initiation factor 3 (IF3) is one of the three protein factors that bind to the small ribosomal subunit and it is required for the initiation of protein biosynthesis in bacteria. IF3 contains two independent domains, N- and C-terminal domains, which are connected by a lysine-rich interdomain linker. IF3 undergoes large-scale movements and conformational changes upon binding to the 30S subunit and also during the functional regulation of initiation. However, the precise dynamic interplay of the two domains and the molecular mechanism of IF3 is not well understood. A high-resolution 3D structure of a complete IF3 in bacteria has not been solved. Pseudomonas aeruginosa, a gram-negative opportunistic pathogen, is a primary cause of nosocomial infections in humans. Here we report the NMR chemical shift assignments of IF3 from P. aeruginosa as the first step toward NMR structure determination and interaction studies. Secondary structure analyses deduced from the NMR chemical shift data identified nine β-strands and four α-helices arranged in the sequential order β1-β2-α1-β3-β4-α2-β5-α3-β6-α4-β7-β8-β9.