Expression, refolding and crystallization of murine MHC class I H-2D^b in complex with human β₂-microglobulin

Mouse MHC class I H-2Db in complex with human β2m and the LCMV-derived peptide gp33 has been produced and crystallized. Resolution of the structure of this complex combined with the structural comparison with the previously solved crystal structure of H-2Db/mβ2m/gp33 should lead to a better understanding of how the β2m subunit affects the overall conformation of MHC complexes as well as the stability of the presented peptides. β₂-Microglobulin (β₂m) is non-covalently linked to the major histocompatibility (MHC) class I heavy chain and interacts with CD8 and Ly49 receptors. Murine MHC class I can bind human β₂m (hβ₂m) and such hybrid molecules are often used in structural and functional studies. The replacement of mouse β₂m (mβ₂m) by hβ₂m has important functional consequences for MHC class I complex stability and specificity, but the structural basis for this is unknown. To investigate the impact of species-specific β₂m subunits on MHC class I conformation, murine MHC class I H-2D^b in complex with hβ₂m and the peptide gp33 derived from lymphocytic choriomeningitis virus (LCMV) has been expressed, refolded in vitro and crystallized. Crystals containing two complexes per asymmetric unit and belonging to the space group P2₁, with unit-cell parameters a = 68.1, b = 65.2, c = 101.9 Å, β = 102.4°, were obtained