Stuart McNicholas

Overview of the CCP4 suite and current developments

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

REFMAC5 dictionary: organization of prior chemical knowledge and guidelines for its use

One of the most important aspects of macromolecular structure refinement is the use of prior chemical knowledge. Bond lengths, bond angles and other chemical properties are used in restrained refinement as subsidiary conditions. This contribution describes the organization and some aspects of the use of the flexible and human/machine-readable dictionary of prior chemical knowledge used by the maximum-likelihood macromolecular-refinement program REFMAC5. The dictionary stores information about monomers which represent the constitutive building blocks of biological macromolecules (amino acids, nucleic acids and saccharides) and about numerous organic/inorganic compounds commonly found in macromolecular crystallography. It also describes the modifications the building blocks undergo as a result of chemical reactions and the links required for polymer formation. More than 2000 monomer entries, 100 modification entries and 200 link entries are currently available. Algorithms and tools for updating and adding new entries to the dictionary have also been developed and are presented here. In many cases, the REFMAC5 dictionary allows entirely automatic generation of restraints within REFMAC5 refinement runs.

Presenting your structures: the CCP4mg molecular-graphics software

The CCP4 molecular-graphics program now uses the Qt framework to provide a modern look and feel. There are many new features including rendering for publication-quality images and sequence alignment.

Developments in the CCP4 molecular-graphics project

Progress towards structure determination that is both high-throughput and high-value is dependent on the development of integrated and automatic tools for electron-density map interpretation and for the analysis of the resulting atomic models. Advances in map-interpretation algorithms are extending the resolution regime in which fully automatic tools can work reliably, but at present human intervention is required to interpret poor regions of macromolecular electron density, particularly where crystallographic data is only available to modest resolution [for example, I/sigma(I) < 2.0 for minimum resolution 2.5 A]. In such cases, a set of manual and semi-manual model-building molecular-graphics tools is needed. At the same time, converting the knowledge encapsulated in a molecular structure into understanding is dependent upon visualization tools, which must be able to communicate that understanding to others by means of both static and dynamic representations. CCP4 mg is a program designed to meet these needs in a way that is closely integrated with the ongoing development of CCP4 as a program suite suitable for both low- and high-intervention computational structural biology. As well as providing a carefully designed user interface to advanced algorithms of model building and analysis, CCP4 mg is intended to present a graphical toolkit to developers of novel algorithms in these fields.

The CCP4 molecular-graphics project

This new package will provide easy-to-use access to crystallographic structure solution, model building and structure analysis. It will be possible for any developer to integrate scientific software into the system.

Conformation‐independent structural comparison of macromolecules with ProSMART

The Procrustes Structural Matching Alignment and Restraints Tool (ProSMART) has been developed to allow local comparative structural analyses independent of the global conformations and sequence homology of the compared macromolecules. This allows quick and intuitive visualization of the conservation of backbone and side-chain conformations, providing complementary information to existing methods.

The new CCP4 Coordinate Library as a toolkit for the design of coordinate-related applications in protein crystallography

The new CCP4 Coordinate Library is a development aiming to provide a common layer of coordinate-related functionality to the existing applications in the CCP4 suite, as well as a variety of tools that can simplify the design of new applications where they relate to atomic coordinates. The Library comprises a wide spectrum of useful functions, ranging from parsing coordinate formats and elementary editing operations on the coordinate hierarchy of biomolecules, to high-level functionality such as calculation of secondary structure, interatomic bonds, atomic contacts, symmetry transformations, structure superposition and many others. Most of the functions are available in a C++ object interface; however, a Fortran interface is provided for compatibility with older CCP4 applications. The paper describes the general principles of the Library design and the most important functionality. The Library, together with documentation, is available under the LGPL license from the CCP4 suite version 5.0 and higher.

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.

Three-dimensional structures of two heavily N-glycosylated Aspergillus sp. family GH3 β-d-glucosidases

The three-dimensional structures of two industrially important family GH3 β-d-glucosidases from A. fumigatus and A. oryzae are reported at 1.95 Å resolution. Both enzymes show extensive N-glycosylation. The extensive glycans pose special problems for crystallographic refinement, and new techniques and protocols were developed especially for this work.

Automating tasks in protein structure determination with the clipper python module: Automating Tasks in Protein Structure Determination

Scripting programming languages provide the fastest means of prototyping complex functionality. Those with a syntax and grammar resembling human language also greatly enhance the maintainability of the produced source code. Furthermore, the combination of a powerful, machine‐independent scripting language with binary libraries tailored for each computer architecture allows programs to break free from the tight boundaries of efficiency traditionally associated with scripts. In the present work, we describe how an efficient C++ crystallographic library such as Clipper can be wrapped, adapted and generalized for use in both crystallographic and electron cryo‐microscopy applications, scripted with the Python language. We shall also place an emphasis on best practices in automation, illustrating how this can be achieved with this new Python module.