1-aminoadenosine and 1-octen-3-ol

The X-ray structure of bovine Odorant Binding Protein (bOBP) revealed its association as a domain swapped dimer. bOBP, devoid of any cysteines, contrasts with other mammalian OBPs, which are monomeric and possess at least one disulfide bridge. We have produced a mutant of bOBP in which a glycine residue was inserted after position 121. This mutation yielded a monomeric bOBP-121Gly+ in which domain swapping has been reverted. Here, we have subsequently introduced two mutations, Trp64Cys and His155Cys, in view to stabilize the putative monomer with a disulfide bridge. We have determined the crystal structure of this triple mutant at 1.65 A resolution. The mutant protein is monomeric, stabilized by a disulfide bridge between Trp64Cys and His155Cys, with a backbone superimposable to that of native bOBP, with the exception of the hinge and of the 10 residues at the C-terminus. bOBP triple mutant binds 1-amino-anthracene, 1-octen-3-ol (bOBP co-purified ligand) and other ligands with microM Kd values comparable to those of the swapped dimer.

Topics: Adenosine; Amino Acid Sequence; Animals; Binding Sites; Cattle; Chromatography, Gel; Circular Dichroism; Crystallography, X-Ray; Dimerization; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Octanols; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Receptors, Odorant; Sequence Homology, Amino Acid