H1 Family Histones in the Nucleus
CONTROL OF BINDING AND LOCALIZATION BY THE C-TERMINAL DOMAIN*
- John P. H. Th'ng‡,
- Rohyun Sung§,
- Ming Ye§ and
- Michael J. Hendzel, A CIHR new investigator and an Alberta Heritage Foundation for Medical Research scholar§¶
- ‡Thunder Bay Regional Health Sciences Centre, Medical Sciences Division, Northern Ontario School of Medicine, Thunder Bay, Ontario P7B 6V4, Canada and the §Department of Oncology, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada
- ↵¶ To whom correspondence should be addressed: Dept. of Oncology, University of Alberta, 11560 University Ave., Edmonton, Alberta, Canada T6G 1Z2. Tel.: 780-432-8439; Fax: 780-432-8892; E-mail: michaelh{at}cancerboard.ab.ca.
Abstract
H1 histones bind to DNA as they enter and exit the nucleosome. H1 histones have a tripartite structure consisting of a short N-terminal domain, a highly conserved central globular domain, and a lysine-and arginine-rich C-terminal domain. The C-terminal domain comprises approximately half of the total amino acid content of the protein, is essential for the formation of compact chromatin structures, and contains the majority of the amino acid variations that define the individual histone H1 family members. This region contains several cell cycle-regulated phosphorylation sites and is thought to function through a charge-neutralization process, neutralizing the DNA phosphate backbone to allow chromatin compaction. In this study, we use fluorescence microscopy and fluorescence recovery after photobleaching to define the behavior of the individual histone H1 subtypes in vivo. We find that there are dramatic differences in the binding affinity of the individual histone H1 subtypes in vivo and differences in their preference for euchromatin and heterochromatin. Further, we show that subtype-specific properties originate with the C terminus and that the differences in histone H1 binding are not consistent with the relatively small changes in the net charge of the C-terminal domains.
- Received February 11, 2005.
- Revision received May 16, 2005.
- The American Society for Biochemistry and Molecular Biology, Inc.
