Structural basis for nematode eIF4E binding an m(2,2,7)G-Cap and its implications for translation initiation

Nucleic Acids Res. 2011 Nov 1;39(20):8820-32. doi: 10.1093/nar/gkr650. Epub 2011 Sep 29.

Abstract

Metazoan spliced leader (SL) trans-splicing generates mRNAs with an m(2,2,7)G-cap and a common downstream SL RNA sequence. The mechanism for eIF4E binding an m²²⁷G-cap is unknown. Here, we describe the first structure of an eIF4E with an m(2,2,7)G-cap and compare it to the cognate m⁷G-eIF4E complex. These structures and Nuclear Magnetic Resonance (NMR) data indicate that the nematode Ascaris suum eIF4E binds the two different caps in a similar manner except for the loss of a single hydrogen bond on binding the m(2,2,7)G-cap. Nematode and mammalian eIF4E both have a low affinity for m(2,2,7)G-cap compared with the m⁷G-cap. Nematode eIF4E binding to the m⁷G-cap, m(2,2,7)G-cap and the m(2,2,7)G-SL 22-nt RNA leads to distinct eIF4E conformational changes. Additional interactions occur between Ascaris eIF4E and the SL on binding the m(2,2,7)G-SL. We propose interactions between Ascaris eIF4E and the SL impact eIF4G and contribute to translation initiation, whereas these interactions do not occur when only the m(2,2,7)G-cap is present. These data have implications for the contribution of 5'-UTRs in mRNA translation and the function of different eIF4E isoforms.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ascaris suum
  • Dinucleoside Phosphates / chemistry
  • Eukaryotic Initiation Factor-4E / chemistry*
  • Eukaryotic Initiation Factor-4E / metabolism
  • Helminth Proteins / chemistry*
  • Helminth Proteins / metabolism
  • Models, Molecular
  • Peptide Chain Initiation, Translational*
  • Protein Binding
  • Protein Conformation
  • RNA Cap Analogs / chemistry*
  • RNA, Spliced Leader / chemistry

Substances

  • Dinucleoside Phosphates
  • Eukaryotic Initiation Factor-4E
  • Helminth Proteins
  • RNA Cap Analogs
  • RNA, Spliced Leader
  • 7-methyl-diguanosine triphosphate