CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION ANALYSIS OF GINGIPAIN R2 FROM PORPHYROMONAS-GINGIVALIS IN COMPLEX WITH H-D-PHE-PHE-ARG-CHLOROMETHYLKETONE

Gingipain R2 is a 50 kDa proteinase from the oral pathogenic bacterium Porphyromonas gingivalis. This proteinase, which displays no signific ant sequence homology to any protein previously analyzed by X-ray crys tallography, has been crystallized using the vapor diffusion method. T wo different crystal forms were obtained from a solution containing po lyethylene glycol (MW 8,000) (space group P2(1)2(1)2(1)) or magnesium sulfate (space group R3) as precipitating agent. Complete diffraction data sets have been collected up to 2.0 and 2.9 Angstrom resolution, r espectively. Cell dimensions are a = 51.9 Angstrom, b = 79.9 Angstrom, and c = 99.6 Angstrom (P2(1)2(1)2(1)), and a = b = 176.6 Angstrom, an d c = 143.4 Angstrom (R3). Considerations of the possible values of V- m accounts for the presence of one monomer per asymmetric unit in the case of the orthorhombic crystal form, whereas the rhombohedral crysta l form, together with the analysis of the self-rotation function, coul d accommodate a tetramer in the asymmetric unit.