Ronan Keegan

Overview of the CCP4 suite and current developments

An overview of the CCP4 software suite for macromolecular crystallography is given.

Automated search-model discovery and preparation for structure solution by molecular replacement.

A novel automation pipeline for macromolecular structure solution by molecular replacement is described. There is a special emphasis on the discovery and preparation of a large number of search models, all of which can be passed to the core molecular-replacement programs. For routine molecular-replacement problems, the pipeline automates what a crystallographer might do and its value is simply one of convenience. For more difficult cases, the pipeline aims to discover the particular template structure and model edits required to produce a viable search model and may succeed in finding an efficacious combination that would be missed otherwise. The pipeline is described in detail and a number of examples are given. The examples are chosen to illustrate successes in real crystallography problems and also particular features of the pipeline. It is concluded that exploring a range of search models automatically can be valuable in many cases.

MrBUMP: an automated pipeline for molecular replacement

An automation pipeline for macromolecular structure solution by molecular replacement with a special emphasis on the discovery and preparation of a large number of search models is described.

AMPLE: a cluster-and-truncate approach to solve the crystal structures of small proteins using rapidly computed ab initio models.

Protein ab initio models predicted from sequence data alone can enable the elucidation of crystal structures by molecular replacement. However, the calculation of such ab initio models is typically computationally expensive. Here, a computational pipeline based on the clustering and truncation of cheaply obtained ab initio models for the preparation of structure ensembles is described. Clustering is used to select models and to quantitatively predict their local accuracy, allowing rational truncation of predicted inaccurate regions. The resulting ensembles, with or without rapidly added side chains, solved 43% of all test cases, with an 80% success rate for all-α proteins. A program implementing this approach, AMPLE, is included in the CCP4 suite of programs. It only requires the input of a FASTA sequence file and a diffraction data file. It carries out the modelling using locally installed Rosetta, creates search ensembles and automatically performs molecular replacement and model rebuilding.

Crystal structure of the Nipah virus phosphoprotein tetramerization domain

ABSTRACT The Nipah virus phosphoprotein (P) is multimeric and tethers the viral polymerase to the nucleocapsid. We present the crystal structure of the multimerization domain of Nipah virus P: a long, parallel, tetrameric, coiled coil with a small, α-helical cap structure. Across the paramyxoviruses, these domains share little sequence identity yet are similar in length and structural organization, suggesting a common requirement for scaffolding or spatial organization of the functions of P in the virus life cycle.

Molecular replacement using ab initio polyalanine models generated with ROSETTA

The success of the molecular-replacement method for solving protein structures from experimental diffraction data depends on the availability of a suitable search model. Typically, this is derived from a previously solved structure, sometimes by homology modelling. Very recently, Baker, Read and coworkers have demonstrated a successful molecular-replacement case based on an ab initio model generated by ROSETTA [Qian et al. (2007), Nature (London), 450, 259-264]. In this contribution, a number of additional test cases in which ab initio models generated using modest computational resources give correct molecular-replacement solutions are reported. Unsuccessful cases are also reported for comparison and the factors influencing the success of this route to structure solution are discussed.

Evaluating the solution from MrBUMP and BALBES

The automated pipelines for molecular replacement MrBUMP and BALBES are reviewed, with an emphasis on understanding their output. Conclusions are drawn from their performance in extensive trials.

Routine phasing of coiled-coil protein crystal structures with AMPLE

AMPLE solved 80% of a large set of coiled-coil protein targets of diverse architectures by molecular replacement with ab initio structure predictions. Successes included targets of up to 253 residues, cases of diffraction to only 2.9 Å resolution and macromolecular complexes containing proteins with other folds or DNA.

SPINE workshop on automated X-ray analysis: a progress report

The Structural Proteomics In Europe (SPINE) consortium contained a workpackage to address the automated X-ray analysis of macromolecules. The aim of this workpackage was to increase the throughput of three-dimensional structures while maintaining the high quality of conventional analyses. SPINE was able to bring together developers of software with users from the partner laboratories. Here, the results of a workshop organized by the consortium to evaluate software developed in the member laboratories against a set of bacterial targets are described. The major emphasis was on molecular-replacement suites, where automation was most advanced. Data processing and analysis, use of experimental phases and model construction were also addressed, albeit at a lower level.

CCP4i2: the new graphical user interface to the CCP4 program suite

CCP4i2 is a graphical user interface to the CCP4 (Collaborative Computational Project, Number 4) software suite and a Python language framework for software automation.