Biophysical and Transfection Studies of the diC14-Amidine/DNA Complex Vadim Cherezov, Hong Qiu, Veronique Pector, Michel Vandenbranden, Jean-Marie Ruysschaert, Martin Caffrey  Biophysical Journal  Volume 82, Issue 6, Pages 3105-3117 (June 2002) DOI: 10.1016/S0006-3495(02)75652-X Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 1 Molecular structure of diC14-amidine. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 2 Low- and wide-angle x-ray diffraction from diC14-amidine in excess 10mM Hepes buffer, pH 7.3, at 20°C. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 3 Time-resolved low-angle x-ray diffraction from diC14-amidine in 10mM Hepes buffer, pH 7.3, recorded as a function of temperature in the streak detector mode. The onset and completion temperatures of the Lc-to-Lα transition at 39°C and 42.8°C are indicated. The temperature scan rate was 6°C/h. The detector was translated behind a ∼3-mm slit at a rate of 0.5mm/min. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 4 Diffraction curves from intact diC14-amidine/DNA complexes in excess 10mM Hepes buffer, pH 7.3, at the indicated DNA/lipid molar ratios, ρ, recorded using synchrotron radiation (NSLS) at 30°C. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 5 Diffraction curves from diC14-amidine/DNA samples prepared by lyophilization in excess 10mM Hepes buffer, pH 7.3, at the indicated DNA/lipid molar ratios, ρ, recorded using synchrotron radiation (ESRF) at 30°C. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 6 Dependence of the intensity of the first order small-angle reflection from diC14-amidine/DNA complexes, ILcα(001), normalized to the sum of intensities of the first order reflection from the Lc phase, ILc(001), and the first order reflection from the lipid/DNA complex, ILcα(001), [ILcα(001)/(ILcα(001)+ILc(001))], on the DNA/lipid mole ratio, ρ. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 7 Dependence of multilamellar repeat distance at 30°C (A) and DNA-DNA spacing at 50°C (B) in diC14-amidine/DNA complexes on DNA/lipid mole ratio, ρ. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 8 Dependence of multilamellar spacing (A) and DNA-DNA spacing (B) in diC14-amidine/DNA complexes on temperature at a DNA/lipid mole ratio of 1.65. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 9 Wide-angle diffraction from diC14-amidine/DNA complexes in buffer at a DNA/lipid mole ratio of 1.65 and from buffer alone recorded as a function of temperature in the vicinity of the lipid chain-melting transition. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 10 Change in the position of the wide-angle reflection as a function of temperature for diC14-amidine/DNA complexes at a DNA/lipid mole ratio1.65. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 11 Polarized light microscopic images of diC14-amidine and diC14-amidine/DNA complexes in excess buffer. DiC14-amidine alone at 25°C (A), diC14-amidine/DNA complex at ρ=0.82 and 25°C before heating (B), and after heating to 70°C and subsequent cooling to 25°C (C). Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 12 Transfection of National Institutes of Health 3T3 cells with diC14-amidine/DNA complexes as a function of the DNA/lipid mole ratio. Activity is measured as the luminescence of the expressed luciferase. RLU, Relative luminescence units. The experiment was performed in duplicate (series 1 and 2). (A) Intact complexes. (B) Complexes lyophilized in the presence of sucrose and rehydrated. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions

Figure 13 Molecular models of the diC14-amidine lipid/DNA complex. Two possible arrangements below the lipid chain melting transition temperature, 23°C, are shown in A and B. They both represent multilamellar structures, with either tilted (A) or interdigitated chains (B), where DNA is intercalated between lipid bilayers. The high temperature arrangement is shown in C where the lipid chains are in the disordered state but the overall organization is multilamellar. Shown in D is an inverted hexagonal phase with DNA strands inside the water channels. This structure is included for comparative purposes only. Neither the x-ray diffraction nor the polarized microscopy studies provided support for the hexagonal arrangement. Biophysical Journal 2002 82, 3105-3117DOI: (10.1016/S0006-3495(02)75652-X) Copyright © 2002 The Biophysical Society Terms and Conditions