Histone-induced conformational changes in DNA as probed by quasi-elastic light scattering

✍ Scribed by K. L. Wun; W. Prins

• Publisher: Wiley (John Wiley & Sons)
• Year: 1975
• Tongue: English
• Weight: 336 KB
• Volume: 14
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1975.360140109

✦ Synopsis

Abstract

Quasi‐elastic light scattering as measured by intensity fluctuation (self‐beat) spectroscopy in the time domain can be profitably used to follow both the translational diffusion D and the dominant internal flexing mode τ~int~ of DNA and its complexes with various histones in aqueous salt solutions. Without histones, DNA is found to have D = 1.6 × 10^−8^ cm^2^/sec and τ~int~ ≅ 5 × 10^−4^ sec in 0.8 M NaCl, 2 M urea at 20°C. Total histone as well as fraction F2A induce supercoiling (D = 2.6 × 10^−8^ cm^2^/sec, τ~int~ ≅ 2.8 × 10^−4^ sec) whereas fraction F1 induces uncoiling (D = 1.0 × 10^−8^ cm^2^/sec, τ~int~ ≅ 9.4 × 10^−4^ sec). Upon increasing the salt concentration to 1.5 M the DNA–histone complex dissociates (D = 1.8 × 10^−8^ cm^2^/sec). Upon decreasing the salt concentration to far below 0.8 M, the DNA–histone complex eventually precipitates as a chromatin gel.