NUCLEAR MAGNETIC RESONANCE OF BIOLOGICAL SYSTEMS
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David P. Weliky Assistant Professor (b. 1963). B.A., 1985, Swarthmore College; Ph.D., 1995, University of Chicago; Postdoctoral Fellow, 1995-97, National Institutes of Health. Biophysical and Physical Chemistry. Solid state nuclear magnetic resonance of biomolecules; structure determination of AIDS-related molecular complexes; development of new structure determination methods for selectively- and fully-labeled proteins. 517-355-9715, Ext. 281 |
Solid state nuclear magnetic resonance spectroscopy is a powerful new approach to determining atomic-level structure and dynamics in noncrystalline biomolecular systems, including proteins in membrane or frozen solution environments. Because of their size and noncrystalline nature, these biologically significant systems are generally not amenable to structure determination by the more conventional techniques of X-ray crystallography and solution NMR spectroscopy. Our research group’s effort is twofold: (1) application of existing solid state NMR methods to structure determination of specific important biomolecular systems; and (2) invention of new methods for macromolecular structure determination.
While doing this research, students learn a variety of skills including peptide synthesis, protein expression and purification, design and construction of NMR equipment, NMR theory and pulse sequence development, and computer simulation. We often collaborate with pharmaceutical companies and other biomedical researchers.
Applications – HIV-1 Fusion Peptide. Fusion between cells and cellular components has an essential role in organismal life and plays an important part in such significant physiological processes as egg fertilization and synaptic transmission in the nervous system. Membrane fusion is also an important step in HIV infection of human cells and is mediated by the hydrophobic ‘fusion peptide’ region of the gp41 viral envelope protein. We are using solid state NMR to determine the conformation, membrane orientation, and aggregation state of the membrane-bound HIV-1 fusion peptide. These data are being incorporated into an atomic-level structural model of fusion-peptide induced membrane fusion.
Methods Development. Our methods development research has short-term and long-term components. In the short-term, we are measuring the chemical shift anisotropy (CSA) principal values of specific nuclei in proteins and correlating these values with secondary structure and hydrogen bonding around these nuclei. These CSA principal value measurements are straightforward, require relatively small amounts of material, and are broadly applicable to protein structure determination.
We also have a long-term interest in solid state NMR of fully labeled peptides and proteins, analogous to the highly successful solution NMR methodologies for protein structure determination. At this time, solid state NMR methods still need to be developed both to assign the individual resonances in the NMR spectra of fully labeled proteins and to determine molecular structure from these spectra. We are developing such methods on systems with a small number of fully labeled amino acids.
Representatative Publications
Probing Hydrogen Bonds in the Antibody-Bound HIV-1 gp120 V3 Loop by Solid State NMR REDOR Measurements, J. J. Balbach, J. Yang, D. P. Weliky, P. J. Steinbach, V. Tugarinov, J. Anglister, and R. Tycko, J. Biomolecular NMR, 16, 313 (2000).
Solid State NMR Evidence for an Antibody-Dependent Conformation of the V3 Loop of HIV-1 gp120, D. P. Weliky, A. E. Bennett, A. Zvi, J. Anglister, P. J. Steinbach, and R. Tycko, Nature Structural Biology, 6, 141 (1999).
Quantitative Conformational Measurements in Solid State NMR by Constant-Time Homonuclear Dipolar Recoupling, A. E. Bennett, D. P. Weliky, and R. Tycko, J. Am. Chem. Soc., 120, 4897 (1998).
Determination of Peptide Conformations by Two-Dimensional Magic Angle Spinning NMR Exchange Spectroscopy with Rotor Synchroni-zation, D. P. Weliky and R. Tycko, J. Am. Chem. Soc., 118, 8487 (1996).
Investigation of Molecular Structure in Solids by Two-Dimensional NMR Exchange Spectroscopy with Magic Angle Spinning, R. Tycko, D. P. Weliky, and A. E. Berger, J. Chem. Phys., 105, 7915 (1996).