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Genome-wide maps of R-loops in Arabidopsis

ABSTRACT: Inspired by the important roles of the special chromatin structure R-loops, here we report a new method, ssDRIP-seq, for genome-wide identification of R-loops, and demonstrate its high efficiency, low bias, and strand-specificity when profiling the R-loops in Arabidopsis. Using this single-strand DNA ligation based library construction technique, we find that Arabidopsis R-loops are formed in both the sense and antisense orientations of genes, and prefer both AT and GC skews. R-loops are prevalent in regions with multiple chromatin modifications, and are negatively correlated with CG DNA hypermethylation. R-loops are strongly enriched in gene promoters and gene bodies, highly associated with noncoding RNA and repetitive genomic regions, and correlated with activated and repressed gene loci. In summary, our analysis reveals that R-loop is a common feature of the Arabidopsis genome, and suggests diverse roles for R-loops in genome organization and gene regulation, thereby providing novel insights into plant nuclear genome formation and function.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE95765 | GEO | 2017/05/31

SECONDARY ACCESSION(S): PRJNA378348

REPOSITORIES: GEO

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

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Project description: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 sensed remain poorly understood. Here we report the discovery of the evolutionally conserved ALBA proteins (AtALBA1&2) functioning as the R-loops sensor of genic regions in higher plant Arabidopsis thaliana. AtALBA1 and 2 form a heterodimer protein complex and localize in the nucleus. While AtALBA1 binds to the DNA-RNA hybrid strand, AtALBA2 associates with single-stranded DNA in the R-loops. AtALBA1&2 preferentially binds to the genic R-loop regions that are associated with active epigenetic marks. Depletion of AtALBA1 or AtALBA2 results in hypersensitivity of plants to DNA damaging agents. Our results demonstrate the unprotected R-loops by loss of AtALBA1&2 are main source of DNA damage through γH2AX ChIP-seq.

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