Crystallization and preliminary X-ray diffraction studies of AsaP1_E294A and AsaP1_E294Q, two inactive mutants of the toxic zinc metallopeptidase AsaP1 from Aeromonas salmonicida subsp. achromogenes.

Two mutants of the toxic extracellular zinc endopeptidase AsaP1 (AsaP1_E294Q and AsaP1_E294A) of Aeromonas salmonicida subsp. achromogenes were expressed in Escherichia coli and crystallized by the vapour-diffusion method. Crystals were obtained using several precipitants and different protein concentrations. Protein crystals were found in a monoclinic (C2) as well as an orthorhombic (P2(1)2(1)2(1)) space group. The crystals belonging to the monoclinic space group C2 had unit-cell parameters a = 103.4, b = 70.9, c = 54.9 A, beta = 109.3 degrees for AsaP1_E294A, and a = 98.5, b = 74.5, c = 54.7 A, beta = 112.4 degrees for AsaP1_E294Q. The unit-cell parameters of the orthorhombic crystal obtained for AsaP1_E294A were a = 57.9, b = 60.2, c = 183.6 A. The crystals of the two different mutants diffracted X-rays beyond 2.0 A resolution.