Comprehensive Multi-Option Structure Determination Pipeline

All existing programs and procedures are being gradually assembled into an integrated system where multiple choices are available along the structure determination path. Partner 1A has extended the development of its Auto-Rickshaw software pipeline for automated structure solution by incorporating into it a combination of molecular replacement and single anomalous diffraction (MRSAD) to complement the pre- existing model refinement, experimental phasing, phase enhancements and automated model building methods. MRSAD phasing requires a search model and/or sequence as well as X-ray data from derivatised protein crystals or X-ray data collected at longer wavelengths. The procedure is initiated by a Web-based graphical user interface for data and parameter input and for monitoring progress in structure determination. A large number of possible structure solution and phase enhancement paths are possible, and the optimal path is selected by the decision-makers as the structure solution evolves. This MRSAD option can be used for reducing the bias from a MR solution, building a complete structure from a partial and/or fragmented model, or when SAD phasing alone is not enough to solve the structure. AutoRickshaw has been successfully running on a large and fast cluster and at the time of the 4th Annual BIOXHIT meeting in April 2008 has been made available to the crystallographic community worldwide.