The structure of the ARE-binding domains of Hu antigen R (HuR) undergoes conformational changes during RNA binding

Acta Crystallogr D Biol Crystallogr. 2013 Mar;69(Pt 3):373-80. doi: 10.1107/S0907444912047828. Epub 2013 Feb 16.

Abstract

Human RNA-binding protein (HuR), a ubiquitously expressed member of the Hu protein family, plays an important role in mRNA degradation and has been implicated as a key post-transcriptional regulator. HuR contains three RNA-recognition motif (RRM) domains. The two N-terminal tandem RRM domains can selectively bind AU-rich elements (AREs), while the third RRM domain (RRM3) contributes to interactions with the poly-A tail of target mRNA and other ligands. Here, the X-ray structure of two methylated tandem RRM domains (RRM1/2) of HuR in their RNA-free form was solved at 2.9 Å resolution. The crystal structure of RRM1/2 complexed with target mRNA was also solved at 2.0 Å resolution; comparisons of the two structures show that HuR RRM1/2 undergoes conformational changes upon RNA binding. Fluorescence polarization assays (FPA) were used to study the protein-RNA interactions. Both the structure and the FPA analysis indicated that RRM1 is the primary ARE-binding domain in HuR and that the conformational changes induce subsequent contacts of the RNA substrate with the inter-domain linker and RRM2 which greatly improve the RNA-binding affinity of HuR.

Keywords: HuR; RNA binding; RRM; conformational change.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AU Rich Elements* / genetics
  • Animals
  • Crystallography, X-Ray
  • DNA Methylation / genetics
  • ELAV Proteins / chemistry*
  • ELAV Proteins / genetics
  • Mice
  • Nucleotide Motifs / genetics
  • Protein Binding / genetics
  • Protein Conformation
  • Protein Interaction Mapping
  • Protein Structure, Tertiary / genetics
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / chemistry*
  • RNA-Binding Proteins / genetics
  • Tandem Repeat Sequences / genetics

Substances

  • ELAV Proteins
  • RNA, Messenger
  • RNA-Binding Proteins

Associated data

  • PDB/4ED5
  • PDB/4EGL