Disassembly of chromatin into ≅50 kb units by detergent

G. Szabó, F. Boldog, N. Wikonkál

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Nuclei isolated from higher eukaryotic cell lines were directly analyzed by field inversion gel electrophoresis. Brief incubation of nuclei with ionic detergents yielded a single band between 50-100 kb. The apparent fragment size decreased to ≅50 kb after proteinase digestion. The latter treatment alone induced less regular, ≦50 kb fragmentation. DNA extracted from detergent and proteinase-treated nuclei also appeared in a band of about 40 kb. Embedding into agarose plugs did not protect nuclei, as opposed to cells, from detergent-induced fragmentation. The phenomenon is strikingly analogous to the double-strand DNA cleavage reactions mediated by topoisomerase II. Our data are compatible with any of the following interpretations: 1.) regularly spaced protein bridges, probably involving topoisomerase II, maintain or control continuity of chromosomal DNA in certain states of higher eukaryotic cells. 2.) The DNA might become accessible to a putative endonuclease at regularly spaced sites upon detergent treatment of isolated nuclei.

Original languageEnglish
Pages (from-to)706-712
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - Jun 15 1990


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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