Crystal structure of the Trypanosoma cruzi EIF4E5 translation factor homologue in complex with mRNA cap-4.Reolon, L.W., Vichier-Guerre, S., de Matos, B.M., Dugue, L., Assuncao, T.R.D.S., Zanchin, N.I.T., Pochet, S., Guimaraes, B.G.
(2019) Nucleic Acids Res 47: 5973-5987
- PubMed: 31066441
- DOI: https://doi.org/10.1093/nar/gkz339
- Primary Citation of Related Structures:
6O7Y, 6O7Z, 6O80
- PubMed Abstract:
Association of the initiation factor eIF4E with the mRNA cap structure is a key step for translation. Trypanosomatids present six eIF4E homologues, showing a low conservation and also differing significantly from the IF4Es of multicellular eukaryotes. On the mRNA side, while in most eukaryotes the mRNA contains cap-0 (7-methyl-GTP), the trypanosomatid mRNA features a cap-4, which is formed by a cap-0, followed by the AACU sequence containing 2'-O-ribose methylations and base methylations on nucleotides 1 and 4. The studies on eIF4E-cap-4 interaction have been hindered by the difficulty to synthesize this rather elaborated cap-4 sequence. To overcome this problem, we applied a liquid-phase oligonucleotide synthesis strategy and describe for the first time the crystal structure of a trypanosomatid eIF4E (T. cruzi EIF4E5) in complex with cap-4. The TcEIF4E5-cap-4 structure allowed a detailed description of the binding mechanism, revealing the interaction mode for the AACU sequence, with the bases packed in a parallel stacking conformation and involved, together with the methyl groups, in hydrophobic contacts with the protein. This binding mechanism evidences a distinct cap interaction mode in comparison with previously described eIF4E structures and may account for the difference of TcEIF4E5-cap-4 dissociation constant in comparison with other eIF4E homologues.
Biochemistry Postgraduate Program, Federal University of Parana, Curitiba, Paraná 81530-000, Brazil.