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Widom, Jonathan Holland, Patricia Ann 2011-05-07T13:26:16Z 2011-05-07T13:26:16Z 10000-01-01 1991 The interaction of the histone H5 globular domain with DNA and chromatin was studied using several physical and chemical techniques, including electron microscopy, dynamic light scattering, equilibrium density and velocity ultracentrifugation, and chemical crosslinking. The globular domain of histone H5 was employed in reconstitution experiments designed to test its ability to fold chromatin compared with intact H5. Binding and protein analyses showed that GH5 binds to chromatin in native stoichiometric amounts. Nuclease digestion experiments suggested that GH5 positions itself properly in chromatin and protects spacer DNA from digestion. Electron microscopy and dynamic light scattering studies showed that when GH5 is present in native or two-fold stoichiometric amounts in reconstituted chromatin, chromatin folding is not induced. Several lines of evidence show that GH5 forms cooperative complexes with DNA. Electron microscopy of GH5-DNA mixtures showed that 2 distinct classes of DNA coexist: free DNA and DNA complexed with GH5. Free DNA and complexes were separated into two nonoverlapping components on CsCl density gradients. Chemical crosslinking studies demonstrated that GH5 molecules were in close proximity on GH5-DNA complexes. Despite having very different sedimentation coefficients, complexes and free DNA could not be completely resolved on sucrose gradients. Many of the fractionated complexes were not completely coated with GH5, and free DNA cosedimented with complexes. This behavior was also seen in a comparison study of H1-DNA complexes, and requires that previous conclusions based on measured stoichiometries be reinterpreted. The results of this study lead to new conclusions about the mechanism of H1 action in chromatin, and they point to important new avenues for future research. Made available in DSpace on 2011-05-07T13:26:16Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9124425.pdf: 6502988 bytes, checksum: fa157fabd85801abb06cbd5f782c8066 (MD5) Previous issue date: 1991 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:54:45Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:25:28-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9124425 (UMI)AAI9124425 http://hdl.handle.net/2142/22016 eng Copyright 1991 Holland, Patricia Ann Chemistry, Biochemistry Physical and biochemical studies of histone H1 and its globular domain text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.