Crystallization and preliminary X-ray diffraction analysis of a recombinant cysteine-free mutant of crmA

CrmA is an unusual serpin that has a reactive-center loop one residue short er than other members of the superfamily. Most interestingly, crmA has inhi bitory activity against both cysteine and serine proteinases involved in th e regulation of cell apoptosis. The three-dimensional structure of crmA wil l give insight into the mechanism that this serpin employs to inhibit both cysteine and the serine proteinases, as well as help to explain the signifi cance of the shorter reactive-center loop. The monodisperse cysteine-free m utant of crmA was crystallized in the presence of phosphate salts. Crystals diffract to 2.90 Angstrom and belong to space group P2(1)2(1)2(1), with un it-cell parameters a = 42.67, b = 93.15, c = 101.63 Angstrom.