DNA-Folding by a Stably DNA-Linked Protein in Eukaryotic Chromatin

  • Zoya Avramova
  • Peter Petrov
  • Roumen Tsanev

Abstract

Higher levels of structural organization of DNA is achieved through its interaction with different proteins. These interactions are abolished by reagents destroying noncovalent associations, hydrogen bonding and S-S bridges. However, in chromatin of different origin a fraction of nonhistone proteins was found whose association with DNA could not be disrupted by such reagents (Lesko and Emery, 1966; Krauth and Werner, 1979; Neuer et al., 1983; Avramova and Tsanev, 1987). The presence of such a protein fraction was proved by in vitro iodination and by in vivo incorporation of labelled aminoacids. This firmly bound protein fraction showed several unusual properties: 1) After iodination it could not enter the Polyacrylamide gels upon electrophoresis. This made impossible the estimation of its molecular mass; 2) The two-dimensional tryptic peptide map of the iodinated protein isolated from eleven different chromatins — Drosophila, fish, frog and rat liver, chicken erythrocytes, rat and ram sperm, Guerin tumor cells, mouse Friend cells, maize leaves and roots — showed a practically identical pattern (Avramova et al., 1989a, b), revealing its high evolutionary conservation; 3) By in vivo labelling of DNA and of the protein it was found that this protein was metabolically stable, transmitted to the progeny like DNA (Avramova et al., 1988a); 4) Chemical and enzymic analysis of the DNA-protein linkage of the stable complex have suggested a bond of a phosphodiester type.

Keywords

Maize Electrophoresis Polypeptide Polyacrylamide 

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Copyright information

© Plenum Press, New York 1990

Authors and Affiliations

  • Zoya Avramova
    • 1
  • Peter Petrov
    • 1
  • Roumen Tsanev
    • 1
  1. 1.Institute of Molecular BiologyBulgarian Academy of SciencesSofiaBulgaria

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