title: AFM of self-assembled lambda DNA-histone networks.
abstract: Atomic force microscopy (AFM) was used to investigate the self-assembly behavior of λ-DNA and histones at varying histone:DNA ratios. Without histones and at the lowest histone:DNA ratio (less than one histone per 1000 base pairs of DNA), the DNA appeared as individual (uncomplexed), double-stranded DNA molecules. At increasing histone concentrations (one histone per 500, 250 and 167 base pairs of DNA), the DNA molecules started to form extensive polygonal networks of mostly pentagons and hexagons. The observed networks might be one of the naturally occurring, stable DNA-histone structures. The condensing effects of the divalent cations Mg(2+) and Ca(2+) on the DNA-histone complexes were also investigated. The networks persisted at high Mg(2+) concentration (20mM) and the highest histone concentration. At high Ca(2+) concentration and the highest histone concentration, the polygonal network disappeared and, instead, individual, tightly condensed aggregates were formed.
authors.affiliation: Department of Physics, College of Science, China Agricultural University, Beijing 100083, China.
authors.forename: YuYing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Physics, Wake Forest University, Winston Salem 27109, USA. Electronic address: gutholdm@wfu.edu.
authors.forename: Martin
authors.initials: M
authors.lastname: Guthold
authors.affiliation: Department of Physics, Wake Forest University, Winston Salem 27109, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Snyder
authors.affiliation: Department of Physics, College of Science, China Agricultural University, Beijing 100083, China. Electronic address: hongfeng@cau.edu.cn.
authors.forename: HongFeng
authors.initials: H
authors.lastname: Lu
mesh_terms: D004247:DNA / Q000737:chemistry*; D006657:Histones / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D013499:Surface Properties
chemical_list: D006657:Histones; D004247:DNA
keywords: Hexagon; Histone; Lambda DNA (or λ-DNA); Network; Pentagon; Self-assembly