title: Resolving the space-group ambiguity of crystals of tomato fruit polygalacturonase.
abstract: The first polygalacturonase from a plant, tomato fruit PG2, has been crystallized and data have been collected to a resolution of 1.87 A. The autoindexing program strongly favors one of the primitive orthorhombic cells. A plausible molecular-replacement solution for two molecules in the asymmetric unit has been found for data assigned to space group P2(1)2(1)2(1). Although the numerical criteria and the electron-density maps are reasonable for this solution, manually adjusted models do not refine to an R factor below 0.48. Visual inspection of hkl Bragg planes does not reveal a breakdown in mm symmetry. Nevertheless, the correct space group has been determined to be P2(1), with similar unit-cell parameters, a beta angle of 90.04 degrees and four molecules in the asymmetric unit. The R(sym) of 0.053 for data processed in P2(1)2(1)2(1) is very similar to the R(sym) of 0.047 for the same data processed in P2(1). Comparisons of the intermediate results using the P2(1)2(1)2(1) and P2(1) data sets are provided and the subtle indications of an initial erroneous space-group assignment are discussed.
authors.affiliation: University of California, Irvine, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Heffron
authors.forename: Stephan
authors.initials: S
authors.lastname: Watkins
authors.forename: Rhonda
authors.initials: R
authors.lastname: Moeller
authors.forename: Aise Huma
authors.initials: AH
authors.lastname: Taban
authors.forename: Rafal
authors.initials: R
authors.lastname: Butowt
authors.forename: Dean
authors.initials: D
authors.lastname: DellaPenna
authors.forename: Frances
authors.initials: F
authors.lastname: Jurnak
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D005638:Fruit / Q000201:enzymology; D018551:Solanum lycopersicum / Q000201:enzymology*; D008958:Models, Molecular; D011096:Polygalacturonase / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D011096:Polygalacturonase