Identification of a nucleic acid binding domain in eukaryotic initiation factor eIFiso4G from wheat

J Biol Chem. 1999 Apr 9;274(15):10603-8. doi: 10.1074/jbc.274.15.10603.


Higher plants have two complexes that bind the m7G-cap structure of mRNA and mediate interactions between mRNA and ribosomal subunits, designated eIF4F and eIFiso4F. Both complexes contain a small subunit that binds the 5'-cap structure of mRNA, and a large subunit, eIF4G or eIFiso4G, that binds other translation factors and RNA. Sequence-specific proteases were used to cleave native cap-binding complexes into structural domains, which were purified by affinity chromatography. We show here that eIFiso4G contains a central protease-resistant domain that binds specifically to nucleic acids. This domain spans Gln170 to Glu443 and includes four of the six homology blocks shared by eIFiso4G and eIF4G. A slightly shorter overlapping sequence, from Gly202 to Lys445, had no nucleic acid binding activity, indicating that the N-terminal end of the nucleic acid binding site lies within Gln170 to Arg201. The binding of the central domain and native eIFiso4F to RNA homopolymers and double- and single-stranded DNAs was studied. Both molecules had highest affinity for poly(G) and recognized single- and double-stranded sequences.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Cellulose / analogs & derivatives
  • Cellulose / metabolism
  • Chromatography, High Pressure Liquid
  • Consensus Sequence
  • Eukaryotic Initiation Factor-4G
  • Humans
  • Mass Spectrometry
  • Molecular Sequence Data
  • Nucleic Acids / metabolism*
  • Oligodeoxyribonucleotides / metabolism
  • Peptide Initiation Factors / metabolism*
  • RNA Cap Analogs / metabolism
  • RNA Caps / metabolism
  • RNA, Messenger / metabolism
  • Rabbits
  • Sepharose / metabolism
  • Triticum / metabolism*
  • Zea mays


  • Eukaryotic Initiation Factor-4G
  • Nucleic Acids
  • Oligodeoxyribonucleotides
  • Peptide Initiation Factors
  • RNA Cap Analogs
  • RNA Caps
  • RNA, Messenger
  • oligo(dT)-cellulose
  • 7-methylguanosine triphosphate
  • Cellulose
  • Sepharose
  • phosphocellulose