engleski

Mean-field electrostatics explained through application to viruses

I will expose the standard Poisson-Boltzmann (PB) and Debye-Huckel (DH) approaches to electrostatic interactions in salty solutions. These will be illustrated through elaborated examples. In particular, I will show elementary application of PB and DH approaches to viruses. The electrostatic interactions are known to be important for the assembly [4] and structure [1, 5, 6] of viruses which come in two essential “flavors” – ones containing the, usually, single-stranded RNA molecule, and the others containing the, usually, double-stranded DNA molecule. Both type of genomes are strongly negatively charged in the solution, and their encapsulation in the viral protein coating (capsid) may sometimes require specific form of electrostatic “screening”, such as positive protein tails on the capsid interior, or the encapsulation of the histone-like, positively charged proteins, together with the genome. The worked-through exercises will show the strength and deficiencies of mean-field approaches and indicate the situations where more advanced approaches to electrostatics are needed. The lecture will be based on the following papers authored by the lecturer: [1] A. Šiber, A. Lošdorfer Božič, and R. Podgornik "Energies and pressures in viruses: contribution of nonspecific electrostatic interactions“, Phys.Chem.Chem.Phys. 14, 3746 (2012). [2] A. Lošdorfer Božič, A. Šiber, and R. Podgornik "Electrostatic self-energy of a partially formed spherical shell in salt solution: Application to stability of tethered and fluid shells as models for viruses and vesicles“, Phys. Rev. E 83, 041916 (2011). [3] A. Šiber, R. Zandi and R. Podgornik "Thermodynamics of nanospheres encapsulated in virus capsids“, Phys. Rev. E 81, 051919 (2010). [4] A. Šiber and A. Majdandžić, "Spontaneous curvature as a regulator of the size of virus capsids“, Phys. Rev. E 80, 021910 (2009). [5] A. Šiber and R. Podgornik, "Nonspecific interactions in spontaneous assembly of empty versus functional single-stranded RNA viruses“, Phys. Rev. E 78, 051915 (2008). [6] A. Šiber and R. Podgornik, "Role of electrostatic interactions in the assembly of empty spherical viral capsids", Phys. Rev. E 76, 061906 (2007).

virus; charge; electrostatics; capsid; protein

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