Modelling of bacteriophage capsids and free nucleic acids

Abstract

The reconstruction of sphere shells as realized in bacteriophage capsids can be achieved by ab initio modelling approaches based on a genetic algorithm or simulated annealing. The application of tight constraints such as icosahedral symmetry makes the DAMMIN procedure the method of choice. The ab initio models obtained may be compared with three-dimensional models derived from crystal data. This information, in conjunction with surface calculations and application of specific hydration algorithms, allows the generation of biophysically relevant hydrated three-dimensional models. Modelling free RNA of viruses represents another challenge to advanced modelling intentions. While application of the DAMMIN procedure provides the generation of appropriate models for the overall structure of nucleic acids, inclusion of further constraints improves the biological relevance of the resultant models. This may be achieved by our in-house program SUBSTRUCT, which allows involvement of secondary structure details. © International Union of Crystallography 2007.