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Title: Biological properties of poly-L-lysine/DNA complexes generated by cooperative binding of the polycation
Author: Liu, Ge
Molas, Maria
Grossmann, Gregory A.
Pasumarthy, Murali
Perales Losa, Carlos
Cooper, Mark J.
Hanson, Richard W.
Keywords: ADN
Issue Date: 14-Sep-2001
Publisher: American Society for Biochemistry and Molecular Biology
Abstract: We have evaluated the effect of NaCl concentration on the mode of binding of poly-L-lysine to DNA and the resulting structural and functional features of the condensed DNA particles using DNA precipitation, DNase I resistance, electron microscopy, and receptor-mediated gene transfer assays. At a high concentration of NaCl and in the presence of excess DNA, poly-L-lysine interacted with DNA cooperatively, fully condensing some of the DNA and leaving the rest of the DNA unbound. At low NaCl concentrations, poly-L-lysine molecules interacted with DNA in a noncooperative fashion, i.e. they bind randomly to the whole population of DNA molecules. Cooperative binding of poly-L-lysine to DNA occurred over a narrow range of NaCl concentrations, and the specific salt concentration depended on the length of the poly-L-lysine. The ability of condensed DNA to withstand digestion by DNase I was correlated with the structural features of the condensed DNA as determined by electron microscopy. Using our condensation procedure, cooperative binding of poly-L-lysine to DNA is a necessary prerequisite for the preparation of condensed DNA having a spherical shape and a diameter of 15-30 nm. Condensed DNA, containing galactosylated poly-L-lysine, was evaluated further for the extent and specificity of receptor-mediated gene transfer into HuH-7 human hepatoma cells via the asialoglycoprotein receptor. Efficient receptor-mediated transfection occurred only when condensed DNA complexes had a spherical shape with a diameter of 15-30 nm; asialofetuin, a natural ligand for the asialoglycoprotein receptor, inhibited this process by up to 90%. Our results support the importance of appropriate DNA condensation for the uptake and ultimate expression of DNA in hepatic cells.
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It is part of: Journal of Biological Chemistry, 2001, vol. 276, num. 37, p. 34379-34387
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ISSN: 0021-9258
Appears in Collections:Articles publicats en revistes (Ciències Fisiològiques)

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