In protein crystallography, much time and effort are often required to
trace an initial model from an interpretable electron density map and to refine
it until it best agrees with the crystallographic data. Here, we present a
method to build and refine a protein model automatically and without user
intervention, starting from diffraction data extending to resolution higher
than 2.3 Å and reasonable estimates of crystallographic phases. The
method is based on an iterative procedure that describes the electron density
map as a set of unconnected atoms and then searches for protein-like patterns.
Automatic pattern recognition (model building) combined with refinement, allows
a structural model to be obtained reliably within a few CPU hours. We demonstrate
the power of the method with examples of a few recently solved structures.
