Imperfect pseudo-merohedral twinning in crystals of fungal fatty acid synthase

A case of imperfect pseudo-merohedral twinning in monoclinic crystals of fungal fatty acid synthase is discussed. A space-group transition during crystal dehydration resulted in a Moiré pattern-like interference of the twinned diffraction patterns.

Structure–function studies of the RNA polymerase II elongation complex

X-ray crystallographic and complementary functional studies have contributed significantly to the current understanding of gene transcription. Here, recent structure–function studies on various aspects of the elongation phase of transcription are summarized.

Model-building strategies for low-resolution X-ray crystallographic data

Interpretation of low-resolution X-ray crystallographic data can prove to be a difficult task. The challenges faced in electron-density interpretation, the strategies that have been employed to overcome them and developments to automate the process are reviewed.

X-ray structure determination at low resolution

Refinement is meaningful even at 4 Å or lower, but with present methodologies it should start from high-resolution crystal structures whenever possible.

On vital aid: the why, what and how of validation

The need for validation of macromolecular crystal structures is discussed. A general approach to validation is presented, together with examples of its implementation in the special case of macromolecular crystallography.

Case-controlled structure validation

A case-matched control protocol provides a useful method to compare sets of macromolecular structures.

Structure validation in chemical crystallography

This paper reports on the current status of structure validation in chemical crystallography.

Analysis and validation of carbohydrate three-dimensional structures

The article summarizes the information that is gained from and the errors that are found in carbohydrate structures in the Protein Data Bank. Validation tools that can locate these errors are described.

Prospects for de novo phasing with de novo protein models

In a first systematic exploration of phasing with Rosetta de novo models, it is shown that all-atom refinement of coarse-grained models significantly improves both the model quality and performance in molecular replacement with the Phaser software.

Re-refinement from deposited X-ray data can deliver improved models for most PDB entries

An evaluation of validation and real-space intervention possibilities for improving existing automated (re-)refinement methods.

An emerging consensus for the structure of EmrE

The ongoing story of the structure of EmrE, the archetypical member of the small multidrug-resistance family, is described.

Analysis of errors in the structure determination of MsbA

An analysis is presented of the methodological errors that led to the incorrect structure of MsbA.