8P03

48S late-stage initiation complex with m6A mRNA

Summary for 8P03

• Entry DOI: 10.2210/pdb8p03/pdb
• EMDB information: 17329
• Descriptor: initiator methionylated tRNA, Ribosomal protein S5, 40S ribosomal protein S6, ... (41 entities in total)
• Functional Keywords: translation initiation, ribosome, m6a, methylated mrna, translation
• Biological source: Oryctolagus cuniculus; More
• Total number of polymer chains: 40
• Total formula weight: 1335230.08

Authors

Guca, E.,Lima, L.H.F.,Boissier, F.,Hashem, Y. (deposition date: 2023-05-09, release date: 2024-03-20, Last modification date: 2024-11-13)

Primary citation

Guca, E.,Alarcon, R.,Palo, M.Z.,Santos, L.,Alonso-Gil, S.,Davyt, M.,de Lima, L.H.F.,Boissier, F.,Das, S.,Zagrovic, B.,Puglisi, J.D.,Hashem, Y.,Ignatova, Z.
N 6 -methyladenosine in 5' UTR does not promote translation initiation.
Mol.Cell, 84:584-595.e6, 2024

PubMed Abstract: The most abundant N-methyladenosine (mA) modification on mRNAs is installed non-stoichiometrically across transcripts, with 5' untranslated regions (5' UTRs) being the least conductive. 5' UTRs are essential for translation initiation, yet the molecular mechanisms orchestrated by mA remain poorly understood. Here, we combined structural, biochemical, and single-molecule approaches and show that at the most common position, a single mA does not affect translation yields, the kinetics of translation initiation complex assembly, or start codon recognition both under permissive growth and following exposure to oxidative stress. Cryoelectron microscopy (cryo-EM) structures of the late preinitiation complex reveal that mA purine ring established stacking interactions with an arginine side chain of the initiation factor eIF2α, although with only a marginal energy contribution, as estimated computationally. These findings provide molecular insights into mA interactions with the initiation complex and suggest that the subtle stabilization is unlikely to affect the translation dynamics under homeostatic conditions or stress.

PubMed: 38244546
DOI: 10.1016/j.molcel.2023.12.028

Experimental method

ELECTRON MICROSCOPY (3.04 Å)