Gaetano T. Montelione
Protein Engineering and Rational Drug DesignThe general aim of our research is to use NMR spectroscopy as a tool for protein engineering and rational drug design. We develop new methods for protein solution structure determination and apply these techniques to proteins of pharmaceutical or medical interest. The combined techniques of NMR spectroscopy and conformational energy calculations are being used to (1) determine three dimensional structures of small proteins in solution, (2) determine the structures of protein-protein, protein-receptor, and protein-nucleic acid complexes, (3) characterize effects of amino acid substitutions on protein structure, stability, and dynamics, (4) direct efforts to design and engineer proteins and provide information for rational drug design, and (5) study the molecular mechanisms by which proteins fold into their biologically-active conformations. We have determined three-dimensional structures of several protein growth factors including human and mouse epidermal and hyman type-a transforming growth factors. We are also working with isotope-labeled protein : protease complexes to develop NMR methods useful for characterizing protein - protein interactions.
Recently, we have also determined a three dimensional structure of an IgG-binding domain of staphylococcal Protein A by NMR. We have also characterized its structure bound to an IgG antibody. This IgG-binding domain is structurally homologous to a family of cytokine growth regulating molecules, which themselves bind to IgG-like receptor proteins. These studies provide a model system for understanding details of growth factor : receptor interactions. We are also working to determine 3D structures of RNA-binding proteins and their complexes with both single and double-stranded RNA.
Nuclear relaxation time measurements are also used to characterize intramolecular motion in these small proteins. We have published a detailed study of molecular dynamics and interal motions in human type-a transforming growth factor based on nitrogen-15 relaxation studies, and are in the process of comparing these experimental data with molecular dynamics simulations that provide a motion picture of the structural dynamics of hTGFa in solution. This research has important implications in the fields of protein physical chemistry, molecular design, receptor-ligand interactions, and oncogenesis.