Detection and use of pseudo-translation in determination of protein structures.
Two types of pseudo-translation symmetry, pseudo-twofold translational symmetry and pseudo-body-centered symmetry, have been found in protein crystals of chorismate mutase and cyclophilin C. Statistics on diffraction intensity from these two crystals showed that the presence of pseudo-translations in atomic space yielded a distribution of systematically strong and weak reflections at low resolution. The diffraction pattern resulting from pseudo-translational symmetry was apparently similar to that from true crystallographic symmetry at 4 A resolution, but was distinct at high resolution. Pseudo-translation can be detected by comparing the average magnitudes of certain parity groups of reflections in three-dimensional hkl space. Based on the structures of chorismate mutase and cyclophilin C, the ratio of >1.2 for the average magnitudes of parity groups is sufficient to indicate the existence of pseudo-translation. Although pseudo-translation often makes structure determination more difficult, the additional information of pseudo-translation has been used successfully in the structure determination of chorismate mutase by multiple isomorphous replacement and of cyclophilin C by molecular replacement. Thus, examination of pseudo-translation is recommended at an early stage of structure determination.
Chook
Y M
YM
Laboratory of Cellular Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Lipscomb
W N
WN
Ke
H
H
D002826:Chorismate Mutase / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D000072622:Cyclophilin C; D021983:Cyclophilins; D016572:Cyclosporine / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D020104:Immunophilins / Q000737:chemistry* / Q000378:metabolism; D046911:Macromolecular Substances; D008433:Mathematics; D008958:Models, Molecular; D011487:Protein Conformation
D046911:Macromolecular Substances; D016572:Cyclosporine; D021983:Cyclophilins; D000072622:Cyclophilin C; D020104:Immunophilins; D002826:Chorismate Mutase