Heterochromatin Protein 1 Binds to Nucleosomes and DNA in Vitro*
- From the ‡Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104 and the §Department of Biochemistry and Molecular Genetics, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908
Abstract
Heterochromatin protein 1 (HP1) is a nonhistone chromosomal protein primarily associated with the pericentric heterochromatin and telomeres in Drosophila. The molecular mechanism by which HP1 specifically recognizes and binds to chromatin is unknown. The purpose of this study was to test whether HP1 can bind directly to nucleosomes. HP1 binds nucleosome core particles and naked DNA. HP1-DNA complex formation is length-dependent and cooperative but relatively sequence-independent. We show that histone H4 amino-terminal peptides bind to monomeric and dimeric HP1 in vitro. Acetylation of lysine residues had no significant effect on in vitro binding. The C-terminal chromo shadow domain of HP1 specifically binds H4 N-terminal peptide. Neither the chromo domain nor chromo shadow domain alone binds DNA; intact native HP1 is required for such interactions. Together, these observations suggest that HP1 may serve as a cross-linker in chromatin, linking nucleosomal DNA and nonhistone protein complexes to form higher order chromatin structures.
Footnotes
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↵* This work was supported by National Institutes of Health Grants GM57005 (to J. C. E.), GM50514 (to T. H.), and GM53512 (to C. D. A.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed: Edward A. Doisy Dept. of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1402 South Grand Blvd., St. Louis, MO 63104.
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Published, JBC Papers in Press, July 5, 2000, DOI 10.1074/jbc.M003493200
- Abbreviations:
- HP1
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heterochromatin protein 1
- rHP1
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recombinant HP1
- PAGE
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polyacrylamide gel electrophoresis
- bp
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base pair(s)
- MALDI-TOF
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matrix-assisted laser desorption/ionization time-of-flight
- BSA
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bovine serum albumin
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- Received April 25, 2000.
- Revision received June 30, 2000.
- The American Society for Biochemistry and Molecular Biology, Inc.
