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. 1997 Aug 1;25(15):3095–3101. doi: 10.1093/nar/25.15.3095

Nanoscopic structure of DNA condensed for gene delivery.

D D Dunlap 1, A Maggi 1, M R Soria 1, L Monaco 1
PMCID: PMC146867  PMID: 9224610

Abstract

Scanning force microscopy was used to examine DNA condensates prepared with varying stoichiometries of lipospermine or polyethylenimine in physiological solution. For the first time, individual DNA strands were clearly visualized in incomplete condensates without drying. Using lipospermine at sub-saturating concentrations, discrete nuclei of condensation were observed often surrounded by folded loops of DNA. Similar packing of DNA loops occurred for polyethylenimine-induced condensation. Increasing the amount of the condensing agent led to the progressive coalescence or aggregation of initial condensation nuclei through folding rather than winding the DNA. At over-saturating charge ratios of the cationic lipid or polymer to DNA, condensates had sizes smaller than or equal to those measured previously in electron micrographs. Polyethylenimine condensates were more compact than lipospermine condensates and both produced more homogeneously compacted plasmids when used in a 2-4-fold charge excess. The size and morphology of the condensates may affect their efficiency in transfection.

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Selected References

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  1. Arscott P. G., Li A. Z., Bloomfield V. A. Condensation of DNA by trivalent cations. 1. Effects of DNA length and topology on the size and shape of condensed particles. Biopolymers. 1990;30(5-6):619–630. doi: 10.1002/bip.360300514. [DOI] [PubMed] [Google Scholar]
  2. Behr J. P., Demeneix B., Loeffler J. P., Perez-Mutul J. Efficient gene transfer into mammalian primary endocrine cells with lipopolyamine-coated DNA. Proc Natl Acad Sci U S A. 1989 Sep;86(18):6982–6986. doi: 10.1073/pnas.86.18.6982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bloomfield V. A. Condensation of DNA by multivalent cations: considerations on mechanism. Biopolymers. 1991 Nov;31(13):1471–1481. doi: 10.1002/bip.360311305. [DOI] [PubMed] [Google Scholar]
  4. Boles T. C., White J. H., Cozzarelli N. R. Structure of plectonemically supercoiled DNA. J Mol Biol. 1990 Jun 20;213(4):931–951. doi: 10.1016/S0022-2836(05)80272-4. [DOI] [PubMed] [Google Scholar]
  5. Boussif O., Lezoualc'h F., Zanta M. A., Mergny M. D., Scherman D., Demeneix B., Behr J. P. A versatile vector for gene and oligonucleotide transfer into cells in culture and in vivo: polyethylenimine. Proc Natl Acad Sci U S A. 1995 Aug 1;92(16):7297–7301. doi: 10.1073/pnas.92.16.7297. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bustamante C., Rivetti C. Visualizing protein-nucleic acid interactions on a large scale with the scanning force microscope. Annu Rev Biophys Biomol Struct. 1996;25:395–429. doi: 10.1146/annurev.bb.25.060196.002143. [DOI] [PubMed] [Google Scholar]
  7. Chattoraj D. K., Gosule L. C., Schellman A. DNA condensation with polyamines. II. Electron microscopic studies. J Mol Biol. 1978 May 25;121(3):327–337. doi: 10.1016/0022-2836(78)90367-4. [DOI] [PubMed] [Google Scholar]
  8. Eickbush T. H., Moudrianakis E. N. The compaction of DNA helices into either continuous supercoils or folded-fiber rods and toroids. Cell. 1978 Feb;13(2):295–306. doi: 10.1016/0092-8674(78)90198-8. [DOI] [PubMed] [Google Scholar]
  9. Gershon H., Ghirlando R., Guttman S. B., Minsky A. Mode of formation and structural features of DNA-cationic liposome complexes used for transfection. Biochemistry. 1993 Jul 20;32(28):7143–7151. doi: 10.1021/bi00079a011. [DOI] [PubMed] [Google Scholar]
  10. Hansma P. K., Elings V. B., Marti O., Bracker C. E. Scanning tunneling microscopy and atomic force microscopy: application to biology and technology. Science. 1988 Oct 14;242(4876):209–216. doi: 10.1126/science.3051380. [DOI] [PubMed] [Google Scholar]
  11. Haynes M., Garrett R. A., Gratzer W. B. Structure of nucleic acid-poly base complexes. Biochemistry. 1970 Oct 27;9(22):4410–4416. doi: 10.1021/bi00824a600. [DOI] [PubMed] [Google Scholar]
  12. Labat-Moleur F., Steffan A. M., Brisson C., Perron H., Feugeas O., Furstenberger P., Oberling F., Brambilla E., Behr J. P. An electron microscopy study into the mechanism of gene transfer with lipopolyamines. Gene Ther. 1996 Nov;3(11):1010–1017. [PubMed] [Google Scholar]
  13. Lyubchenko Y. L., Shlyakhtenko L. S. Visualization of supercoiled DNA with atomic force microscopy in situ. Proc Natl Acad Sci U S A. 1997 Jan 21;94(2):496–501. doi: 10.1073/pnas.94.2.496. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Marquet R., Wyart A., Houssier C. Influence of DNA length on spermine-induced condensation. Importance of the bending and stiffening of DNA. Biochim Biophys Acta. 1987 Aug 25;909(3):165–172. doi: 10.1016/0167-4781(87)90074-1. [DOI] [PubMed] [Google Scholar]
  15. Marx K. A., Reynolds T. C. Spermidine-condensed phi X174 DNA cleavage by micrococcal nuclease: torus cleavage model and evidence for unidirectional circumferential DNA wrapping. Proc Natl Acad Sci U S A. 1982 Nov;79(21):6484–6488. doi: 10.1073/pnas.79.21.6484. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Marx K. A., Ruben G. C. Evidence for hydrated spermidine-calf thymus DNA toruses organized by circumferential DNA wrapping. Nucleic Acids Res. 1983 Mar 25;11(6):1839–1854. doi: 10.1093/nar/11.6.1839. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Plum G. E., Arscott P. G., Bloomfield V. A. Condensation of DNA by trivalent cations. 2. Effects of cation structure. Biopolymers. 1990;30(5-6):631–643. doi: 10.1002/bip.360300515. [DOI] [PubMed] [Google Scholar]
  18. Sternberg B., Sorgi F. L., Huang L. New structures in complex formation between DNA and cationic liposomes visualized by freeze-fracture electron microscopy. FEBS Lett. 1994 Dec 19;356(2-3):361–366. doi: 10.1016/0014-5793(94)01315-2. [DOI] [PubMed] [Google Scholar]
  19. Vengerov Y. Y., Semenov T. E., Streltsov S. A., Makarov V. L., Khorlin A. A., Gursky G. V. Torus-shaped particles formed due to intermolecular condensation of circular DNA upon interaction with synthetic tripeptide. FEBS Lett. 1985 Jan 21;180(1):81–84. doi: 10.1016/0014-5793(85)80236-2. [DOI] [PubMed] [Google Scholar]
  20. Wheeler C. J., Sukhu L., Yang G., Tsai Y., Bustamente C., Felgner P., Norman J., Manthorpe M. Converting an alcohol to an amine in a cationic lipid dramatically alters the co-lipid requirement, cellular transfection activity and the ultrastructure of DNA-cytofectin complexes. Biochim Biophys Acta. 1996 Apr 3;1280(1):1–11. doi: 10.1016/0005-2736(95)00256-1. [DOI] [PubMed] [Google Scholar]
  21. Wolfert M. A., Seymour L. W. Atomic force microscopic analysis of the influence of the molecular weight of poly(L)lysine on the size of polyelectrolyte complexes formed with DNA. Gene Ther. 1996 Mar;3(3):269–273. [PubMed] [Google Scholar]
  22. Zabner J., Fasbender A. J., Moninger T., Poellinger K. A., Welsh M. J. Cellular and molecular barriers to gene transfer by a cationic lipid. J Biol Chem. 1995 Aug 11;270(32):18997–19007. doi: 10.1074/jbc.270.32.18997. [DOI] [PubMed] [Google Scholar]
  23. Zhou X., Huang L. DNA transfection mediated by cationic liposomes containing lipopolylysine: characterization and mechanism of action. Biochim Biophys Acta. 1994 Jan 19;1189(2):195–203. doi: 10.1016/0005-2736(94)90066-3. [DOI] [PubMed] [Google Scholar]

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