title: Methylation of adenine in the nuclear DNA of Tetrahymena is internucleosomal and independent of histone H1.
abstract: There are about 50 copies of each chromosome in the somatic macronucleus of the ciliated protozoan TETRAHYMENA: Approximately 0.8% of the adenine residues in the macronuclear DNA of Tetrahymena are methylated to N6-methyladenine. The degree of methylation varies between sites from a very low percentage to >90%. In this study a correlation was found between nucleosome positioning and DNA methylation. Eight GATC sites with different levels of methylation were examined. There was a direct correlation between the degree of methylation and proximity to linker DNA at these sites. Although methylation occurs preferentially in linker DNA, the patterns and extent of methylation in a histone H1 knockout strain were virtually indistinguishable from those in wild-type cells.
authors.affiliation: Department of Biology, Wehr Life Sciences, Marquette University, PO Box 1881, Milwaukee, WI 53201-1881, USA. kathleen.karrer@marquette.edu
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Karrer
authors.forename: Teresa A
authors.initials: TA
authors.lastname: VanNuland
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000378:metabolism*; D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D019175:DNA Methylation; D016054:DNA, Protozoan / Q000378:metabolism*; D017353:Gene Deletion; D006657:Histones / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000378:metabolism*; D013768:Tetrahymena / Q000235:genetics* / Q000378:metabolism
chemical_list: D000225:Adenine; D000227:Adenine Nucleotides; D016054:DNA, Protozoan; D006657:Histones; D009707:Nucleosomes; C000730567:6-methyladenine