title: H1 binding unwinds DNA. Evidence from topological assays.
abstract: The preference of the linker histones to bind to superhelical DNA in comparison with linear or relaxed molecules suggests that these proteins might, in turn, change the twist and/or writhe of DNA molecules upon binding. In order to explore such a possibility, we looked for changes in the linking number of plasmid pBR322 caused by H1 binding, using assays that involve nicking and resealing of DNA strands. Two types of enzymes were used, eukaryotic topoisomerase I and prokaryotic DNA ligase. The results revealed that H1 binding causes unwinding of the DNA, with the unwinding angle being approximately 10 degrees . The globular domain of histone H1 is also capable of unwinding DNA, but to a lesser degree.
authors.affiliation: Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331-7305, USA.
authors.forename: M
authors.initials: M
authors.lastname: Ivanchenko
authors.forename: A
authors.initials: A
authors.lastname: Hassan
authors.forename: K
authors.initials: K
authors.lastname: van Holde
authors.forename: J
authors.initials: J
authors.lastname: Zlatanova
mesh_terms: D000818:Animals; D002645:Chickens; D004265:DNA Helicases; D011088:DNA Ligases; D004264:DNA Topoisomerases, Type I; D004278:DNA, Superhelical / Q000648:ultrastructure*; D004268:DNA-Binding Proteins / Q000502:physiology; D006657:Histones / Q000502:physiology*; D007700:Kinetics; D009690:Nucleic Acid Conformation; D010957:Plasmids
chemical_list: D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D006657:Histones; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I; D011088:DNA Ligases