1 April 1992 Rotational diffusion of nucleosomes: role of the N-terminal histone domains in structural transitions
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Abstract
The rotational diffusion of nucleosome core particles were measured using the fluorescence anisotropy decay of ethidium intercalated into the core particle DNA as a function of ionic strength. The `native' form of the core particle (ionic strength from 0.001 to 0.1 M) has a rotational correlation time ((phi) max) of approximately 170 ns. At higher salt concentrations (phi) max rises slowly from approximately 170 ns at 0.1 M NaCl to a value of approximately 230 ns at 0.35 M NaCl, a point just above physiological ionic strength; we call this change the moderate-salt transition. (phi) max remains constant at approximately 230 ns until the onset of the `high-salt dissociation' which occurs above 0.7 M NaCl. This dissociation begins with the release of H2A-H2B dimers; increasing DNA flexibility in this salt range prohibits accurate measurement of the rotational correlation time beyond this point. Light treatment of the ore particles with trypsin to remove the N-terminal histone domains abolishes the plateau in (phi) max between 0.35 and 0.65 M NaCl. Thus, the moderate-salt transition derives from the release of these N-terminal ends from the body of the core particle. The anisotropy decays show no evidence for DNA release from the core particle at salt concentrations below 0.65 M.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David W. Brown, David W. Brown, Enoch W. Small, Enoch W. Small, } "Rotational diffusion of nucleosomes: role of the N-terminal histone domains in structural transitions", Proc. SPIE 1640, Time-Resolved Laser Spectroscopy in Biochemistry III, (1 April 1992); doi: 10.1117/12.58276; https://doi.org/10.1117/12.58276
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