Combined pseudo-merohedral twinning, non-crystallographic symmetry and pseudo-translation in a monoclinic crystal form of the gammadelta T-cell ligand T10.
T10 is a non-classical class Ib-like major histocompatibility complex (MHC) cell-surface antigen which binds directly to certain gammadelta T-cell receptors in the absence of any exogenous and endogenous ligands, such as peculiar lipids or glycolipids. The crystal structure at 2.5 A resolution of murine T10 was determined by molecular replacement using data from an almost perfectly twinned monoclinic crystal. The space group is P2(1), with unit-cell parameters a = 78.2, b = 70.0, c = 139.2 A, beta = 106.8 degrees. Self-rotation function analysis and various intensity statistics revealed the presence of pseudo-merohedral twinning, but these tests underestimated the true twin fraction of alpha approximately 0.46. Native Patterson analyses pointed to the presence of pseudo-translation among the four molecules present in the asymmetric unit. Data analysis, structure determination and model refinement are discussed.
Rudolph
Markus G
MG
Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. markus.rudolph@bio.uni-goettingen.de
Wingren
Christer
C
Crowley
Michael P
MP
Chien
Yueh Hsiu
YH
Wilson
Ian A
IA
D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry* / Q000276:immunology; D003460:Crystallization; D018360:Crystallography, X-Ray; D006183:H-2 Antigens / Q000737:chemistry*; D051379:Mice; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology
D000954:Antigens, Surface; D006183:H-2 Antigens; D016692:Receptors, Antigen, T-Cell, gamma-delta; C493536:T10 antigen, mouse