A novel role for Gemin5 in mRNA translation

Nucleic Acids Res. 2009 Feb;37(2):582-90. doi: 10.1093/nar/gkn979. Epub 2008 Dec 9.

Abstract

In eukaryotic cells translation initiation occurs through two alternative mechanisms, a cap-dependent operating in the majority of mRNAs, and a 5'-end-independent driven by internal ribosome entry site (IRES) elements, specific for a subset of mRNAs. IRES elements recruit the translation machinery to an internal position in the mRNA through a mechanism involving the IRES structure and several trans-acting factors. Here, we identified Gemin5 protein bound to the foot-and-mouth disease virus (FMDV) and hepatitis C virus (HCV) IRES using two independent approaches, riboproteomic analysis and immunoprecipitation of photocrosslinked factors. Functional analysis performed in Gemin5 shRNA-depleted cells, or in in vitro translation reactions, revealed an unanticipated role of Gemin5 in translation control as a down-regulator of cap-dependent and IRES-driven translation initiation. Consistent with this, pull-down assays showed that Gemin5 forms part of two distinct complexes, a specific IRES-ribonucleoprotein complex and an IRES-independent protein complex containing eIF4E. Thus, beyond its role in snRNPs biogenesis, Gemin5 also functions as a modulator of translation activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Down-Regulation
  • Humans
  • Peptide Chain Initiation, Translational*
  • Peptides / metabolism
  • RNA, Messenger / chemistry*
  • RNA, Viral / chemistry*
  • RNA, Viral / metabolism
  • RNA-Binding Proteins / metabolism
  • Regulatory Sequences, Ribonucleic Acid*
  • SMN Complex Proteins / metabolism
  • SMN Complex Proteins / physiology*

Substances

  • Peptides
  • RNA, Messenger
  • RNA, Viral
  • RNA-Binding Proteins
  • Regulatory Sequences, Ribonucleic Acid
  • SMN Complex Proteins