9AX7
70S initiation complex (tRNA-fMet M1 + CUG start codon)
This is a non-PDB format compatible entry.
Summary for 9AX7
| Entry DOI | 10.2210/pdb9ax7/pdb |
| Related | 9AX8 |
| EMDB information | 43929 43930 |
| Descriptor | 50S ribosomal protein L33, 30S ribosomal protein S5, 30S ribosomal protein S6, ... (57 entities in total) |
| Functional Keywords | translation initiation, trna-fmet m1, frameshifting, ribosome |
| Biological source | Escherichia coli More |
| Total number of polymer chains | 54 |
| Total formula weight | 2181190.37 |
| Authors | Mattingly, J.M.,Nguyen, H.A.,Dunham, C.M. (deposition date: 2024-03-06, release date: 2024-09-18, Last modification date: 2025-03-19) |
| Primary citation | Mattingly, J.M.,Nguyen, H.A.,Roy, B.,Fredrick, K.,Dunham, C.M. Structural analysis of noncanonical translation initiation complexes. J.Biol.Chem., 300:107743-107743, 2024 Cited by PubMed Abstract: Translation initiation is a highly regulated, multi-step process which is critical for efficient and accurate protein synthesis. In bacteria, initiation begins when mRNA, initiation factors, and a dedicated initiator fMet-tRNA bind the small (30S) ribosomal subunit. Specific binding of fMet-tRNA in the peptidyl (P) site is mediated by the inspection of the fMet moiety by initiation factor IF2 and of three conserved G-C base pairs in the tRNA anticodon stem by the 30S head domain. Tandem A-minor interactions form between 16S ribosomal RNA nucleotides A1339 and G1338 and tRNA base pairs G30-C40 and G29-C41, respectively. Swapping the G30-C40 pair of tRNA with C-G reduces discrimination against the noncanonical start codon CUG in vitro, suggesting crosstalk between gripping of the anticodon stem and recognition of the start codon. Here, we solved electron cryomicroscopy structures of E. coli 70S initiation complexes containing an fMet-tRNA G30-C40 variant paired to noncanonical CUG start codon, in the presence or absence of IF2 and the non-hydrolyzable GTP analog GDPCP, alongside structures of 70S initiation complexes containing this tRNA variant paired to the canonical bacterial start codons AUG, GUG, and UUG. We find that the M1 mutation weakens A-minor interactions between tRNA and 16S nucleotides A1339 and G1338, with IF2 strengthening the interaction of G1338 with the tRNA minor groove. These structures suggest how even slight changes to the recognition of the fMet-tRNA anticodon stem by the ribosome can impact start codon selection. PubMed: 39222680DOI: 10.1016/j.jbc.2024.107743 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.63 Å) |
Structure validation
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