Affinity resins containing enzymatically resistant mRNA cap analogs--a new tool for the analysis of cap-binding proteins

RNA. 2012 Jul;18(7):1421-32. doi: 10.1261/rna.032078.111. Epub 2012 May 15.

Abstract

Cap-binding proteins have been routinely isolated using m⁷GTP-Sepharose; however, this resin is inefficient for proteins such as DcpS (scavenger decapping enzyme), which interacts not only with the 7-methylguanosine, but also with the second cap base. In addition, DcpS purification may be hindered by the reduced resin capacity due to the ability of DcpS to hydrolyze m⁷GTP. Here, we report the synthesis of new affinity resins, m⁷GpCH₂pp- and m⁷GpCH₂ppA-Sepharoses, with attached cap analogs resistant to hydrolysis by DcpS. Biochemical tests showed that these matrices, as well as a hydrolyzable m⁷GpppA-Sepharose, bind recombinant mouse eIF4E²⁸⁻²¹⁷ specifically and at high capacity. In addition, purification of cap-binding proteins from yeast extracts confirmed the presence of all expected cap-binding proteins, including DcpS in the case of m⁷GpCH₂pp- and m⁷GpCH₂ppA-Sepharoses. In contrast, binding studies in vitro demonstrated that recombinant human DcpS efficiently bound only m⁷GpCH₂ppA-Sepharose. Our data prove the applicability of these novel resins, especially m⁷GpCH₂ppA-Sepharose, in biochemical studies such as the isolation and identification of cap-binding proteins from different organisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatography, Affinity / methods*
  • Eukaryotic Initiation Factor-4E / chemistry
  • Humans
  • Mice
  • Protein Binding
  • RNA Cap Analogs / chemistry*
  • RNA Cap-Binding Proteins / analysis
  • RNA Cap-Binding Proteins / chemistry*
  • Sepharose / analogs & derivatives
  • Sepharose / chemical synthesis*

Substances

  • Eukaryotic Initiation Factor-4E
  • RNA Cap Analogs
  • RNA Cap-Binding Proteins
  • m7GpppA
  • Sepharose