title: Methylation-dependent binding of wheat nuclear proteins to the promoter region of ribosomal RNA genes.
abstract: Here, we report data on the binding of wheat nuclear proteins (NP) to the promoter region of the rDNA intergenic spacer (IGS), with emphasis on the possible effects of methylation with M-HpaII on this binding. We have found that a number of NP specifically bind to the rDNA promoter, and to upstream and downstream IGS sequences. A 240-kDa NP binds specifically to a 174-bp fragment located downstream from the transcription start point (tsp), and this fragment competes with a 135-bp subrepeat element fragment for specific binding to this 240-kDa NP. Specific binding of the 240-kDa NP to the 174-bp fragment is greatly inhibited by methylation of internal cytosine residues in its two CCGG sites, whereas NP binding to the 135-bp subrepeat element is not affected by M-HpaII methylation. A 202-bp fragment containing the tsp is partially homologous to the 174-bp downstream region fragment. Nevertheless, it neither binds the 240-kDa NP nor is its binding to NP affected by methylation of CCGG sites. Thus, multiple specific NP may be involved in rDNA transcription initiation. Methylation-dependent inhibition of rDNA transcription initiation appears to be mediated by direct interference with the binding of some of these transcription factors to their respective regulatory elements.
authors.affiliation: A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
authors.forename: V V
authors.initials: VV
authors.lastname: Ashapkin
authors.forename: T T
authors.initials: TT
authors.lastname: Antoniv
authors.forename: B F
authors.initials: BF
authors.lastname: Vanyushin
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D018744:DNA, Plant / Q000737:chemistry / Q000378:metabolism*; D004275:DNA, Ribosomal / Q000737:chemistry / Q000378:metabolism*; D015257:DNA-Cytosine Methylases / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D014908:Triticum / Q000235:genetics / Q000378:metabolism*
chemical_list: D018744:DNA, Plant; D004275:DNA, Ribosomal; D009687:Nuclear Proteins; C029641:DNA modification methylase HpaII; D015257:DNA-Cytosine Methylases