Bifunctional DNA glycosylase/lyase, which excises 5-methylcytosine (5-meC) and 5-hydroxymethylcytosine (5-hmeC), leaving an apyrimidinic (AP) site that is subsequently incised by the lyase activity (PubMed:25240767). Generates 3'-phosphor-alpha,beta-unsaturated aldehyde (3'-PUA) as a primary 5-meC excision intermediate (PubMed:25228464). Prevents DNA hypermethylation, specifically in the promoter of otherwise silenced loci. May be involved in DNA repair through its nicking activity on methylated DNA. Binds with similar affinity to both methylated and non-methylated DNA. Highly distributive behavior on DNA substrates containing multiple 5-meC residues. Involved with Pol IV in the remodeling of the 5S rDNA chromatin via DNA methylation modifications during the first days of development post-germination. Participates in UV-B induced- and oxidative DNA damage repair (PubMed:24155752). 2'-deoxyribonucleotide-(2'-deoxyribose 5'-phosphate)-2'-deoxyribonucleotide-DNA = a 3'-end 2'-deoxyribonucleotide-(2,3-dehydro-2,3-deoxyribose 5'-phosphate)-DNA + a 5'-end 5'-monophospho-2'-deoxyribonucleoside-DNA + H(+) Binds 1 [4Fe-4S] cluster. The cluster does not appear to play a role in catalysis, but is probably involved in the proper positioning of the enzyme along the DNA strand. Stimulated by ZDP (PubMed:22325353). Stimulated by XRCC1 (PubMed:23316050). Interacts (via the central region) with ZDP (PubMed:22325353). Binds to RPA2A (PubMed:16271867, PubMed:16326925). Interacts with XRCC1 (PubMed:23316050). Interacts probably with a complex made of MBD7, IDM1, IDM2 and IDM3 (Probable). Interacts with APE1L (PubMed:25569774). Co-localizes in nucleoplasmic foci with APE1L and ZDP, two components of the DNA demethylase machinery. Expressed ubiquitously in both vegetative and reproductive organs. Down-regulated by UV-B. The N-terminal lysine-rich domain (112-260) is required for non-specific binding to DNA and for efficient activity on 5-meC. The glycosylase domain (510-1073) is inactive on 5-meC and 5-hmeC excisions but retains residual AP activity. Addition of the C-terminal domain (1077-1393) restored partial base excision activity and increases the AP lyase activity. The DEMETER domain, which is present in proteins of the subfamily, is related to the J-domain, but lacks some important conserved residues. Decreased response to UV-B radiation (PubMed:24155752). No visible phenotype (PubMed:25569774). Although strongly related to DNA glycosylase proteins, it differs from these proteins. The DNA repair function may not exist. MBD7 binds to chromatin at high mCG density regions and then recruits IDM2 and IDM3, thus bringing IDM1 to the methylated DNA. The specific histone H3 acetylation marks produced by IDM1 create a chromatin environment that facilitate the binding of ROS1 to erase DNA methylation. Belongs to the DNA glycosylase family. DEMETER subfamily.