title: Nucleosome structural changes induced by binding of non-histone chromosomal proteins HMGN1 and HMGN2.
abstract: Interactions between the nucleosome and the non-histone chromosomal proteins (HMGN1 and HMGN2) were studied by circular dichroism (CD) spectroscopy to elucidate structural changes in the nucleosome induced by HMGN binding. Unlike previous studies that used a nucleosome extracted from living cells, in this study we utilized a nucleosome reconstituted from unmodified recombinant histones synthesized in Escherichia coli and a 189-bp synthetic DNA fragment harboring a nucleosome positioning sequence. This DNA fragment consists of 5'-TATAAACGCC-3' repeats that has a high affinity to the histone octamer. A nucleosome containing a unique octamer-binding sequence at a specific location on the DNA was produced at sufficiently high yield for spectroscopic analysis. CD data have indicated that both HMGN1 and HMGN2 can increase the winding angle of the nucleosome DNA, but the extent of the structural changes induced by these proteins differs significantly. This suggests HMGN1 and HMGN2 would have different abilities to facilitate nucleosome remodeling.
authors.affiliation: Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
authors.forename: Hideto
authors.initials: H
authors.lastname: Shimahara
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hirano
authors.forename: Kouichi
authors.initials: K
authors.lastname: Ohya
authors.forename: Shun
authors.initials: S
authors.lastname: Matsuta
authors.forename: Sailaja S
authors.initials: SS
authors.lastname: Seeram
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Tate
keywords: CD; CD, circular dichroism; HMG, high mobility group; HMGN; HMGN1 HMGN2, non-histone chromosomal proteins; IPTG, isopropyl-β-d-galactopyranoside; LB, Luria–Bertani; MNase, micrococcal nuclease; NMR, nuclear magnetic resonance; Nucleosome; PCR, polymerase chain reaction; RP-HPLC, reverse phase high performance liquid chromatography; Reconstitution; SDS–PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; Unmodified recombinant histones; phH2A, phH2B, phH3, and phH4, vectors for the gene expression of all four recombinant human core histones H2A, H2B, H3, and H4, respectively