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Structural and Thermodynamic Basis of Epitope Binding by Neutralizing and Nonneutralizing Forms of the Anti-HIV-1 Antibody 4E10.

Rujas E, Gulzar N, Morante K, Tsumoto K, Scott JK, Nieva JL, Caaveiro JM - J. Virol. (2015)

Bottom Line: The conclusions of our structure-function analysis strengthen the idea that to exert effective neutralization, the hydrophobic apex of the solvent-exposed CDR-H3 loop must recognize an antigenic structure more complex than just the linear α-helical epitope and likely constrained by the viral membrane lipids.However, 4E10 (or 4E10-like) antibodies are rarely found in HIV-1-infected individuals or elicited through vaccination.We conclude that the difference between neutralizing and nonneutralizing antibodies of 4E10 is neither structural nor energetic but is related to the capacity to recognize the HIV-1 gp41 epitope inserted in biological membranes.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Bilbao, Spain.

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Thermal stability by DSC. DSC thermograms for WT, WDWD, and ΔLoop are shown as indicated in the panels. Unfolding of the three Fabs shows a single thermal transition between 30 and 90°C. The midpoint of the thermal unfolding (Tm) and the associated enthalpy (ΔH) are also given. The values of Tm and ΔH were obtained by curve fitting with the program ORIGIN 7.0.
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Figure 3: Thermal stability by DSC. DSC thermograms for WT, WDWD, and ΔLoop are shown as indicated in the panels. Unfolding of the three Fabs shows a single thermal transition between 30 and 90°C. The midpoint of the thermal unfolding (Tm) and the associated enthalpy (ΔH) are also given. The values of Tm and ΔH were obtained by curve fitting with the program ORIGIN 7.0.

Mentions: DSC measurements demonstrated that the CDR-H3 mutations did not affect the stability of the ligand-free forms of the Fabs (Fig. 3). The melting temperatures (Tm) determined from the midpoint unfolding transition of WT Fab, WDWD, and ΔLoop were 70, 72, and 72°C, respectively. Therefore, decreasing the hydrophobicity of CDR-H3 at the apex translates into a modest increase in the thermostability of the Fabs (ΔTm = 2°C).


Structural and Thermodynamic Basis of Epitope Binding by Neutralizing and Nonneutralizing Forms of the Anti-HIV-1 Antibody 4E10.

Rujas E, Gulzar N, Morante K, Tsumoto K, Scott JK, Nieva JL, Caaveiro JM - J. Virol. (2015)

Thermal stability by DSC. DSC thermograms for WT, WDWD, and ΔLoop are shown as indicated in the panels. Unfolding of the three Fabs shows a single thermal transition between 30 and 90°C. The midpoint of the thermal unfolding (Tm) and the associated enthalpy (ΔH) are also given. The values of Tm and ΔH were obtained by curve fitting with the program ORIGIN 7.0.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645341&req=5

Figure 3: Thermal stability by DSC. DSC thermograms for WT, WDWD, and ΔLoop are shown as indicated in the panels. Unfolding of the three Fabs shows a single thermal transition between 30 and 90°C. The midpoint of the thermal unfolding (Tm) and the associated enthalpy (ΔH) are also given. The values of Tm and ΔH were obtained by curve fitting with the program ORIGIN 7.0.
Mentions: DSC measurements demonstrated that the CDR-H3 mutations did not affect the stability of the ligand-free forms of the Fabs (Fig. 3). The melting temperatures (Tm) determined from the midpoint unfolding transition of WT Fab, WDWD, and ΔLoop were 70, 72, and 72°C, respectively. Therefore, decreasing the hydrophobicity of CDR-H3 at the apex translates into a modest increase in the thermostability of the Fabs (ΔTm = 2°C).

Bottom Line: The conclusions of our structure-function analysis strengthen the idea that to exert effective neutralization, the hydrophobic apex of the solvent-exposed CDR-H3 loop must recognize an antigenic structure more complex than just the linear α-helical epitope and likely constrained by the viral membrane lipids.However, 4E10 (or 4E10-like) antibodies are rarely found in HIV-1-infected individuals or elicited through vaccination.We conclude that the difference between neutralizing and nonneutralizing antibodies of 4E10 is neither structural nor energetic but is related to the capacity to recognize the HIV-1 gp41 epitope inserted in biological membranes.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Bilbao, Spain.

Show MeSH
Related in: MedlinePlus