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 Å which will be used for molecular replacement.