The DNA Repair Protein XRCC1 Functions in the Plant DNA Demethylation Pathway by Stimulating Cytosine Methylation (5-meC) Excision, Gap Tailoring, and DNA Ligation*

Abstract

Background: Active DNA demethylation in plants is initiated by 5-meC DNA glycosylases of the ROS1/DME family and continued through a base excision repair pathway. Results: XRCC1 stimulates ROS1-initiated demethylation and is required for efficient processing of post-excision intermediates. Conclusion: XRCC1 functions at several stages during active DNA demethylation. Significance: This study identifies a new component of the active DNA demethylation pathway in Arabidopsis.

Cytosine methylation affects the mutability of neighbouring nucleotides in human, Arabidopsis, and rice

“…We think that this locally confined signal is suggestive of BER, which has previously been tipped as a potential culprit behind neighbourhood mutation effects (Qu et al 2012). Experiments in cell extracts have demonstrated the existence of different flavours of BER in both humans and plants (Córdoba-Cañero et al 2009;Martínez-Macías et al 2013), which differ in the number of bases excised and re-synthesized during the repair process. In short-patch BER (SP-BER) only a single nucleotide is added whereas during long-patch BER (LP-BER) multiple bases are excised and re-synthesized.…”

The Role of DNA Methylation in Transposable Element Silencing and Genomic Imprinting

“…Phosphatidylinositol kinase Maternal RdDM [62] thaliana ZINC FINGER DNA 3′ PHOSPHOESTERASE) and DNA repair protein XRCC1 (X-RAY CROSS-COMPLEMENTING GROUP PROTEIN1) were shown to affect DNA demethylation [42,43]. These proteins bind to ROS1 in vitro and act downstream of ROS1 involved in BER; however, it is not yet known whether they also act with DME.…”

Non-coding RNAs and DNA methylation in plants

“…Following base excision, the 3′ phosphate generated by ROS1 is removed by the DNA phosphatase ZDP [63] and the gap is filled with an unmethylated cytosine by the DNA repair system [64]. The Arabidopsis homolog of animal X-RAY REPAIR CROSS COMPLEMENTING 1 (XRCC1) –ATXRCC1 may function in stimulating the activity of ROS1 and ZDP [65]. An RNA-binding protein REPRESSOR OF SILENCING 3 (ROS3) is also involved in DNA demethylation [66].…”