High impact information on ROS1

• Mutations in the Arabidopsis ROS1 locus cause transcriptional silencing of a transgene and a homologous endogenous gene [1].
• ROS1, a repressor of transcriptional gene silencing in Arabidopsis, encodes a DNA glycosylase/lyase [1].
• ROS1 encodes an endonuclease III domain nuclear protein with bifunctional DNA glycosylase/lyase activity against methylated but not unmethylated DNA [1].
• We suggest that ROS1 is a DNA repair protein that represses homology-dependent transcriptional gene silencing by demethylating the target promoter DNA [1].
• The transcriptional silencing in ros1 mutants can be released by the ddm1 mutation or the application of the DNA methylation inhibitor 5-aza-2'-deoxycytidine [1].

Biological context of ROS1

• Mutations in the DNA glycosylase/lyase ROS1 cause transcriptional silencing of the linked RD29A-LUC and 35S-NPTII transgenes in Arabidopsis [2].
• Histone H3 methylation at lysine 4 was increased and histone H3 methylation at lysine 9 was decreased at the 35S promoter in the ros1rpa2 mutant compared to the ros1 background [2].
• We report here the biochemical characterization of ROS1 and the effect of its overexpression on the DNA methylation of target genes [3].
• However, chromatin immunoprecipitation data suggest that histone H3 acetylation is increased and histone H3K9 dimethylation is decreased in the 35S promoter in the ror1 ros1 mutant compared with ros1 [4].

Associations of ROS1 with chemical compounds

• Our data suggest that the DNA glycosylase activity of ROS1 removes 5-methylcytosine from the DNA backbone and then its lyase activity cleaves the DNA backbone at the site of 5-methylcytosine removal by successive beta- and delta-elimination reactions [3].
• Overexpression of ROS1 in transgenic plants led to a reduced level of cytosine methylation and increased expression of a target gene [3].
• The ros1 mutant shows enhanced sensitivity to genotoxic agents methyl methanesulfonate and hydrogen peroxide [1].

References