Crystallization and preliminary X-ray diffraction study of a bacterially produced T-cell antigen receptor Vα domain

A recombinant form of the variable domain of the α chain of a murine T- cell receptor specific for the N-terminal nonapeptide of myelin basin protein in association with the major histocompatibility complex class II I-A(u) molecule has been crystallized in a form suitable for X-ray diffraction analysis. This protein was secreted into the periplasmic space of Escherichia coli cells and affinity-purified using a nickel chelate adsorbent. The crystals are orthorhombic, space group P21212, with unit cell dimensions a=97.7 Å, b=79.6 Å, c=30.4 Å and diffract to beyond 2.2 Å resolution. The ability to crystallize a T-cell receptor domain produced in bacteria strongly suggests that the periplasmic space can provide a suitable environment for the correct in vivo folding of this class of antigen recognition molecules.