1. IF3 structure and alignment.
IF3 structure and alignment. (A) Structures of the IF3N domain from B. stearothermophilus (PDB entry 1TIF) and the IF3C domain from E. coli (PDB entry 2IFE). The side chains of the arginine residues in the IF3C domain are shown and labeled with the residue number. Mutations in the arginine residues that affect binding to the 30S ribosomal subunit are residue numbers 99, 112, 116, 147, and possibly 168. These roughly define the surface that binds to the 30S ribosomal subunit. Mutations of arginine residues reducing IF3 activity involved in mRNA-related functions define a surface comprising residues 129, 131, and 133. (B) Sequence alignment of selected sequences of IF3. Abbreviations, color codes, and secondary-structure nomenclature are as in Fig. 7. Secondary-structure elements are as defined in reference 203. Black vertical arrows indicate residues that have been identified as interacting with the 30S ribosomal subunit by mutagenesis and/or chemical modification. Grey triangles indicate residues whose intensity was most strongly affected by titration with 30S ribosomal subunits in NMR spectroscopy studies (reference 203 and references cited therein). Yellow triangles indicate approximate domain boundaries.
Brian Søgaard Laursen et al. Microbiol. Mol. Biol. Rev. 2005; doi: /MMBR