Crystallization and data collection of the nucleotide-binding domain of Mg-ATPase.

Understanding of how P-type ATPases work would greatly benefit from the elucidation of more high-resolution structures. The nucleotide-binding domain of Mg-ATPase was selected for structural studies because Mg-ATPase is closely related to eukaryotic Ca-ATPase and Na,K-ATPase while the nucleotide-binding domain itself has diverged substantially. Two fragments of Mg-ATPase were cloned in Escherichia coli and purified. The entire cytoplasmic loop (residues 367-673), consisting of the phosphorylation and nucleotide-binding domains, expressed well and was purified in large quantities. The smaller 19.5 kDa nucleotide-binding domain (residues 383-545) expressed less well but formed crystals that diffracted to a resolution of 1.53 A which will be used for molecular replacement.