Chromatin Structure in the Cellular Slime Mold Dictyostelium discoideum

The structure of Dictyostelium discoideum chromatin has been studied by the following techniques: electron microscopy, staphylococcal nuclease digestion, acrylamide gel electrophoresis, sucrose gradient centrifugation, and melting. The basic unit of chromatin is the nucleosome, which is a particle 9...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1978-02, Vol.75 (2), p.705-709
Main Authors: Bakke, Antony C., Wu, Jung-Rung, Bonner, James
Format: Article
Language:English
Subjects:
Biochemistry
Centrifugation, Density Gradient
Chromatin
Chromatin - ultrastructure
Deoxyribonucleases
DNA
DNA - analysis
Electrophoresis, Polyacrylamide Gel
Gels
Histones
Histones - analysis
Liver
Melting
Microscopy, Electron
Monomers
Myxomycetes
Nucleosomes
Staphylococcus
Trypsin
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Summary:The structure of Dictyostelium discoideum chromatin has been studied by the following techniques: electron microscopy, staphylococcal nuclease digestion, acrylamide gel electrophoresis, sucrose gradient centrifugation, and melting. The basic unit of chromatin is the nucleosome, which is a particle 98.6 angstrom in diameter. Approximately 50% of the chromatin is protected from nuclease digestion, but this decreases when protease activity is not inhibited. The nucleosome contains 187 base pairs of DNA, including a 137-base-pair core and a 50-base-pair linker. The monomer nucleosome has an s20,wvalue of 11.5 S on isokinetic sucrose gradients. When the chromatin is melted, four transitions are observed, at 54.5 degrees, 66.7 degrees, 74.9 degrees, and 79.7 degrees. The structure of Dictyostelium chromatin is very similar to that seen in higher eukaryotes.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.75.2.705