Purification, crystallization and preliminary X-ray analysis of the DndE protein from Salmonella enterica serovar Cerro 87, which is involved in DNA phosphorothioation

The phenomenon of DNA phosphorothioation (DNA sulfur modification) is widespread among prokaryotes and may serve as a mechanism to restrict gene transfer among bacteria. DndE is one of five essential proteins that are required for the DNA phosphorothioation process. However, its exact biochemical role in sulfur modification of DNA remains unclear. In this study, the DndE protein homologue from Salmonella enterica serovar Cerro 87 was overexpressed, purified and crystallized. The crystals of the DndE protein diffracted to 2.7 Å resolution and belonged to space group P3₁21. These results will facilitate detailed structural analysis of DndE and further elucidation of its biochemical function.