In a situation so far unique among neurotransmitter receptors, glutamate receptors share amino acid sequence similarities with the bacterial periplasmic binding proteins (PBPs). On the basis of the primary structure similarity of two bacterial periplasmic proteins (lysine/arginine/ornithine- and phosphate-binding proteins) with the chick cerebellar kainate-binding protein (KBP), a member of the ionotropic glutamate receptor family, we have generated a three-dimensional model structure of the KBP extracellular domain. By an interplay between homology modeling and site-directed mutagenesis, we have investigated the kainate binding properties of 55 different mutants (corresponding to 43 positions) and studied the interactions of some of these mutants with various glutamatergic ligands. As a result, we present here the subsets of amino acids accounting for the binding free energies and specificities of KBP for kainate, glutamate, and CNQX and propose a three-dimensional model, at the microarchitectural level, of the glutamatergic binding domain.
|Number of pages||12|
|State||Published - Nov 1996|
Bibliographical noteFunding Information:
Correspondence should be addressed to V. I. T. or A. D.-T. We are indebted to Prof. J.-P. Changeux for his unfailing support and judicious advice and Dr. G. Schreiber for useful discussions. We thank Mrs. C. Lamed for technical assistance. This work was supported by grants to V. I. T from the Minerva Foundation (Munich, Federal Republic of Germany), The Golden Charitable Trust, and the Leo and Julia Forchheimer Center for Molecular Genetics. A. D.-T. and F. M. were supported by grants from the College de France, Centre National de la Recherche Scientifique, the Association Francaise Contre les Myopathies, the Human Frontier Science Program, and the European Economic Community Biotech Program. M. E. and V. I. T. acknowledge the support of the Kimmelman Center for Biomolecular Assembly. V. I. T. holds the Louis and Florence Katz-Cohen professorial chair of Neuropharmacology.