Estimation of anisotropic bending rigidities and spontaneous curvatures of crescent curvature-inducing proteins from tethered-vesicle experimental data

• Published in: Soft matter 2023-07, Vol.19 (28), p.53-531
• Main Authors: Noguchi, Hiroshi, Walani, Nikhil, Arroyo, Marino
• Format: Article
• Language: English
• Subjects: Anisotropy; Bending; Curvature; Density; Deviation; Experimental data; Mean field theory; Membrane proteins; Proteins
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/d3sm00340j

The Bin/amphiphysin/Rvs (BAR) superfamily proteins have a crescent binding domain and bend biomembranes along the domain axis. However, their anisotropic bending rigidities and spontaneous curvatures have not been experimentally determined. Here, we estimated these values from the bound protein densities on tethered vesicles using a mean-field theory of anisotropic bending energy and orientation-dependent excluded volume. The dependence curves of the protein density on the membrane curvature are fitted to the experimental data for the I-BAR and N-BAR domains reported by C. Prévost et al. Nat. Commun ., 2015, 6, 8529 and F.-C. Tsai et al. Soft Matter , 2021, 17, 4254-4265, respectively. For the I-BAR domain, all three density curves of different chemical potentials exhibit excellent fits with a single parameter set of anisotropic bending energy. When the classical isotropic bending energy is used instead, one of the curves can be fitted well, but the others exhibit large deviations. In contrast, for the N-BAR domain, two curves are not well fitted simultaneously the anisotropic model, although it is significantly improved compared to the isotropic model. This deviation likely suggests a cluster formation of the N-BAR domains. We estimated the anisotropic bending rigidities and spontaneous curvatures of I-BAR and N-BAR domains by fitting experimental data, using a mean-field theory of anisotropic bending energy and orientation-dependent excluded volume.