Self-assembled pearling structure of long duplex DNA with histone H1.
We report that complexes of giant DNA molecules with histone H1 proteins form a pearl necklace-like structure when the complexes are prepared by natural dilution from a high-salt solution (2 M NaCl) to a low-salt solution (0.2 M and 50 mM NaCl). We performed real-time observations on the conformational changes of individual T4 phage DNA (166 kb) molecules in bulk solution by fluorescence microscopy. To identify H1-binding regions on individual DNA molecules, we also performed immunofluorescence microscopic observations on the DNA-H1 complex spread on a glass surface. It was found that histone H1 binds DNA in a highly co-operative manner and is accompanied by local folding of the DNA. On the basis of the experimental observations and a theoretical simulation, we propose a self-assembling mechanism for the pearling structure.
Yoshikawa
Y
Y
Department of Food and Nutrition, Nagoya Bunri College, Japan; Graduate School of Human Informatics, Nagoya University, Japan. yoshikaw@scphys.kyoto-u.ac.jp
Velichko
Y S
YS
Ichiba
Y
Y
Yoshikawa
K
K
D017122:Bacteriophage T4 / Q000737:chemistry; D004279:DNA, Viral / Q000737:chemistry* / Q000648:ultrastructure; D006657:Histones / Q000737:chemistry*; D046911:Macromolecular Substances; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D009690:Nucleic Acid Conformation
D004279:DNA, Viral; D006657:Histones; D046911:Macromolecular Substances