Electron Microscopy and Biochemical Properties of Polyamine-Compacted DNA

Isabel Baeza, Carlos Wong, Patricio Gariglio, Luz Maria Rangel, Pedro Chavez, Lourdes Cervantes, Cecilia Montanez, Carlos Arguello

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111 Scopus citations

Abstract

We have obtained polyamine-compacted DNA and analyzed it by electron microscopy employing the method described by Dubochet, suitable for the study of complexes in which the main interactions are of ionic character. In addition, we have developed a simple biochemical method, based on the action of pancreatic DNase I, to demonstrate the condensation of DNA with spermidine. DNA-spermidine complexes are resistant to the action of DNase I, and there is a strong correlation between the presence of condensed DNA forms, both as toroids and as cylinders, and the insensitivity to DNase I activity. We have also shown that pBR322 DNA-spermidine complexes are transcriptionally active in the presence of Escherichia coli RNA polymerase. This supports the data concerning the biological activity of spermidine-condensed DNA.

Original languageEnglish
Pages (from-to)6387-6392
Number of pages6
JournalBiochemistry
Volume26
Issue number20
DOIs
StatePublished - 1987

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