Recognition of non-CpG repeats in Alu and ribosomal RNAs by the Z-RNA binding domain of ADAR1 induces A-Z junctions

Nat Commun. 2021 Feb 4;12(1):793. doi: 10.1038/s41467-021-21039-0.

Abstract

Adenosine-to-inosine (A-to-I) editing of eukaryotic cellular RNAs is essential for protection against auto-immune disorders. Editing is carried out by ADAR1, whose innate immune response-specific cytoplasmic isoform possesses a Z-DNA binding domain (Zα) of unknown function. Zα also binds to CpG repeats in RNA, which are a hallmark of Z-RNA formation. Unexpectedly, Zα has been predicted - and in some cases even shown - to bind to specific regions within mRNA and rRNA devoid of such repeats. Here, we use NMR, circular dichroism, and other biophysical approaches to demonstrate and characterize the binding of Zα to mRNA and rRNA fragments. Our results reveal a broad range of RNA sequences that bind to Zα and adopt Z-RNA conformations. Binding is accompanied by destabilization of neighboring A-form regions which is similar in character to what has been observed for B-Z-DNA junctions. The binding of Zα to non-CpG sequences is specific, cooperative and occurs with an affinity in the low micromolar range. This work allows us to propose a model for how Zα could influence the RNA binding specificity of ADAR1.

Publication types

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

MeSH terms

  • Adenosine Deaminase / genetics
  • Adenosine Deaminase / isolation & purification
  • Adenosine Deaminase / metabolism*
  • Adenosine Deaminase / ultrastructure
  • Alu Elements / genetics*
  • Circular Dichroism
  • Immunity, Innate
  • Nuclear Magnetic Resonance, Biomolecular
  • Nucleic Acid Conformation
  • Protein Domains*
  • RNA Recognition Motif
  • RNA, Ribosomal / genetics
  • RNA, Ribosomal / immunology
  • RNA, Ribosomal / metabolism*
  • RNA, Ribosomal / ultrastructure
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / isolation & purification
  • RNA-Binding Proteins / metabolism*
  • RNA-Binding Proteins / ultrastructure
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / ultrastructure

Substances

  • RNA, Ribosomal
  • RNA-Binding Proteins
  • Recombinant Proteins
  • ADAR protein, human
  • Adenosine Deaminase

Associated data

  • Dryad/10.5061/dryad.pvmcvdnk4