Structure of the azurin mutant nickel-Trp48Met from Pseudomonas aeruginosa at 2.2 Å resolution

The structure of the azurin mutant nickel-Trp48Met from Pseudomonas aeruginosa has been determined by difference Fourier synthesis using phases from the wild-type azurin model. The final crystallographic R value is 0.170 for 17 394 reflections to a resolution of 2.2 Å. The mutant crystallized in the orthorhombic space group P2₁2₁2₁, a = 57.4, b = 80.4, c = 110.3 Å. The four molecules in the asymmetric unit are packed as a dimer of dimers. The nickel metal site of this mutant structure is similar to the zinc metal site in the azurin Asp47 mutant. The site-specific mutation was performed at residue Trp48, which is located in the center of the protein in a highly hydrophobic environment, to investigate its suggested role in the long-range electron-transfer pathway between the disulfide bond on one side of the protein to the Cu centre. The structure around the mutation site Met48 showed no significant change compared with the wild-type structure.