Expression, purification, crystallization and preliminary X-ray diffraction analysis of Deg5 from Arabidopsis thaliana

Arabidopsis thaliana Deg5 is an ATP-independent serine protease which resides on the luminal side of the thylakoid in chloroplasts. Deg5 and another Deg/HtrA-family protease, Deg8, have a synergistic function in the turnover of the D1 protein of photosystem II (PSII), which is prone to damage arising from high light exposure. An inactive mutant of the protein, Deg5(S266A), was overexpressed in Escherichia coli. After purification and crystallization, crystals that diffracted to 2.6 angstrom resolution were obtained. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 109.1, b = 126.0, c = 83.3 angstrom, beta = 102.9 degrees, and contained three molecules in the asymmetric unit. The calculated Matthews coefficient and solvent content were 3.0 angstrom(3) Da(-1) and 59.0%, respectively.