Cryo-EM analysis of the α-form of IF2 reveals its structural changes during translation initiation in E. coli
| Title in English | Cryo-EM analysis of the ?-form of IF2 reveals its structural changes during translation initiation in E. coli |
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| Year of publication | 2025 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | The initiation of bacterial translation is a critical step of gene expression. It involves the binding of the formyl-methionine initiator tRNAfMet into the P-site of the 30S ribosomal subunit, followed by the joining of the ribosomal subunits. Upon binding to the 30S ribosomal initiation complex (IC), initiation factor 1 (IF1) occupies the A-site of the 30S subunit, while initiation factor 2 (IF2), a GTPase, facilitates the docking of the 50S subunit onto the 30S IC, forming the 70S IC. During this process, GTP is hydrolyzed, inorganic phosphate is released, and IF2 detaches, leading to the formation of an elongation-competent 70S ribosome.The detachment of IF2 is driven by significant rearrangements of the C2 domain, as previously described in P. aeruginosa. However, the effect of the IF2 N-terminal domain on these events, along with the timing of IF1's departure, remains a debated aspect in the description of the initiation mechanism. In this study, we utilized the full-length ?-form of E. coli IF2 and ensemble cryo-EM to address long-standing gaps in the bacterial translation initiation mechanism. Our findings show that IF1 leaves the 30S subunit before the 70S initiation complex forms and emphasize the anchoring role of IF2’s N-terminal domain on the 30S subunit. Furthermore, we observed structural changes in IF2 following GTP hydrolysis, offering a thorough and detailed understanding of the translation initiation process. |
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