A protein fraction stably linked to DNA in plant chromatin

✍ Scribed by Zova Avramova; Maria Ivanchenko; Roumen Tsanev

• Publisher: Springer
• Year: 1988
• Tongue: English
• Weight: 759 KB
• Volume: 11
• Category: Article
• ISSN: 0167-4412
• DOI: 10.1007/bf00039020

✦ Synopsis

DNA from the chromatin of roots and shoots of maize seedlings was isolated and extensively deproteinized by repeated high-salt extractions, by subsequent deproteinizations eliminating noncovalently associated proteins and by CsCl density gradient centrifugation. Nevertheless, a protein component resisting all extraction procedures was found firmly associated to plant nuclear DNA. This component was responsible for the 125I uptake when a DNA preparation had been labeled by the chloramine-T method.

A residual oligodeoxynucleotide-oligopeptide complex was obtained after extensive digestions of the initial DNAoprotein complex with proteases and nucleases. The stability of this complex to different chemical treatments suggested a phosphoester type of a linkage. The hydrolysis of this complex by phosphodiesterases indicated that the protein component was linked to plant chromosomal DNA through a phosphodiester bond formed by a hydroxyaminoacid and a 5 '-end DNA phosphate. Two-dimensional tryptic peptide mapping of the proteins isolated from the two maize chromatins revealed a high degree of similarity to the corresponding proteins of animal origin. Its conservative structure suggests an important role for this protein component in the functioning of the eukaryotic genome.