ALBA protein complex reads genic R-loops to maintain genome stability in Arabidopsis

Sci Adv. 2019 May 15;5(5):eaav9040. doi: 10.1126/sciadv.aav9040. eCollection 2019 May.

Abstract

The R-loop, composed of a DNA-RNA hybrid and the displaced single-stranded DNA, regulates diverse cellular processes. However, how cellular R-loops are recognized remains poorly understood. Here, we report the discovery of the evolutionally conserved ALBA proteins (AtALBA1 and AtALBA2) functioning as the genic R-loop readers in Arabidopsis. While AtALBA1 binds to the DNA-RNA hybrid, AtALBA2 associates with single-stranded DNA in the R-loops in vitro. In vivo, these two proteins interact and colocalize in the nucleus, where they preferentially bind to genic regions with active epigenetic marks in an R-loop-dependent manner. Depletion of AtALBA1 or AtALBA2 results in hypersensitivity of plants to DNA damaging agents. The formation of DNA breaks in alba mutants originates from unprotected R-loops. Our results reveal that the AtALBA1 and AtALBA2 protein complex is the genic R-loop reader crucial for genome stability in Arabidopsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics*
  • Cell Nucleus / metabolism
  • DNA / analysis
  • DNA Damage
  • Epigenesis, Genetic
  • Genetic Complementation Test*
  • Genome, Plant*
  • Genomic Instability*
  • Green Fluorescent Proteins / metabolism
  • Mutation*
  • Phylogeny
  • Protein Multimerization
  • RNA / analysis
  • RNA-Binding Proteins / genetics*
  • Recombinant Fusion Proteins / genetics

Substances

  • AT1G20220 protein, Arabidopsis
  • AT1G76010 protein, Arabidopsis
  • Arabidopsis Proteins
  • RNA-Binding Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • RNA
  • DNA