Solid-state and solution NMR, protein structure, cataract, membrane proteins, physical chemistry, chemical biology
2005 Camille and Henry Dreyfus New Faculty Award
2009 NSF CAREER Award
2008 AAAS Fellow
Postdoctoral researcher, University of California, Berkeley, 2002-2005
We develop and use modern NMR methods to investigate biological macromolecules, including membranes and membrane proteins, disease-related and functional protein aggregates, and other locally ordered protein networks. Locally ordered protein networks are biomaterials that have significant short-range order but lack long-range crystallinity. Although these materials are difficult to study because of their compositional heterogeneity, they are central to many interesting biophysical questions. Graduate and undergraduate students are involved in all aspects of this research, including design and construction of NMR equipment, development of pulse sequences, and preparation of protein and membrane samples.
NMR technology development for structural biology of difficult protein systems.
Current instrumentation projects include the development of a 4-channel 1H/13C/2H/15N MAS probe for protein studies and next-generation switched-angle spinning (SAS) NMR probes for biological samples. The 4-channel probe will enable us to make optimal use of 2H in multidimensional NMR studies. The quadrupolar splitting of 2H, a spin-1 nucleus, is a sensitive probe of local conformation and mobility. Despite the popularity of partial deuteration, which is often used to simplify the 1H spectra of proteins, because few probes are capable of detecting 2H directly, particularly not with simultaneous 1H/13C/2H/15N capability. Our new probe will allow many multi-dimensional experiments to be performed on highly deuterated protein samples, making it possible to use 2H as a probe of local order and mobility in solid and semi-solid samples, and to perform 2H-13C and 2H-15N correlations. These advances will provide general methodology applicable to all solid and semi-solid proteins.
Switched-angle spinning (SAS) NMR is an extension of MAS in which the spinning axis is varied during a single experiment, such that an evolution off the magic angle is followed by detection at the magic angle. This results in an isotropic spectrum in the direct dimension correlated to the chemical shift anisotropy or dipolar couplings obtained in the indirect dimension. Therefore, SAS measures the isotropic spectrum that is needed to assign the resonances of different chemical sites, while providing valuable information that would be lost in a simple MAS experiment, all without changing the concentration of any components or the temperature. We are developing biomolecular NMR experiments in which all the anisotropic interactions are recoupled by spinning off the magic angle, and then symmetry-based sequences are used for selective decoupling. This approach takes advantage of the mobility of the sample, making it an asset instead of a liability. Finally, this method will enable measurement of dipolar couplings and structure determination of membrane proteins, many of which do not assume their biologically relevant conformations in isotropic solution.
Understanding the molecular basis of crystallin protein solubility and cataract.
One important biological application of our NMR methodology is the structural proteins of the eye lens, the crystallins. These proteins generate the refractive properties of the lens, and are generally not regenerated; they must remain stable and soluble for a lifetime. Cataract, which is a major cause of blindness, results when structural crystallins aggregate, causing opacity of the lens. Structural information about the native crystallin oligomers and the aggregates formed when this system breaks down will lead to greater understanding of cataract formation and possibly to future non-surgical interventions.
Kingsley, C. N., Bierma, J. C., Pham, V., Martin, R. W. The γS-crystallin Proteins From the Antarctic Nototheniid Toothfish: a Model System for Investigating Differential Resistance to Chemical and Thermal Denaturation. The Journal of Physicl Chemistry B. 118(47):13544-53.
Martin, R. W. (2014). NMR studies of eye lens crystallins. In R. K. Harris, R. Wasylishen (Eds.), eMagRes (Encyclopedia of NMR). Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom. John Wiley & Sons, Ltd.
Kingsley, C. N., Brubaker, W. D., Markovic, S., Diehl, A., Brindley, A. J., Oschkinat, H., Martin, R. W. (2013). Preferential and specific binding of human αB-crystallin to a cataract-related variant of γS-crystallin. Structure, 12(12), 2221-2227. (Featured on the cover).
Jiang, J., Golchert, K. J., Kingsley, C. N., Brubaker, W. D., Martin, R. W., Mukamel, S. (2013). Exploring the aggregation propensity of γS-crystallin protein variants using two- dimensional spectroscopic tools. Journal of Physical Chemistry B, 117(46), 14294-14301.
Donovan, K. J., Allen, M. A., Martin, R. W., Shaka, A. J. (2012). Improving the double quantum ltered COSY experiment by "Moving Tube NMR". Journal of Magnetic Resonance, 219, 41-45. (Featured on the cover).
Brindley, A. J., Martin, R. W. (2012). Effect of divalent cations on DMPC/DHPC bicelle formation and alignment. Langmuir, 28(20), 7788-7796.
Thureau, P., Ziarelli, F., Thevand, A., Martin, R. W., Farmer, P. J., Viel, S., Mollica, G. (2012). Probing motional behavior of eumelanin and pheomelanin by solid-state NMR: new insights into the pigment properties. Chemistry - A European Journal, 18, 10689-10700.
Brubaker, W. D., Martin, R. W. (2012). 1H, 13C, and 15N assignments of wild-type human γS-crystallin and its cataract-related variant γS-G18V. Biomolecular NMR Assignments, 6(1), 63-67.
Espinosa, C. A., Thureau, P., Shapiro, R. A., Livak, I. M., Martin, R. W. (2011). Modulation of cross polarization in motionally averaged solids by Variable Angle Spinning NM. Chemical Physics Letters, 508(4-6), 314-319.
Brubaker, W. D., Freites, J. A., Golchert, K. J., Shapiro, R. A., Morikis, V., Tobias, D. J., Martin, R. W. (2011). Separating instability from aggregation propensity in γS-crystallin variants. Biophyical Journal, 100, 498-506.
Nowacka, A., Mohr, P., Norrman, J., Martin, R. W. (2010). Polarization transfer solid-state NMR for studying amphiphiles in coexisting solid and liquid crystalline phases. Langmuir, 26, 16848-16856.
Litvak, I. M., Espinosa, C. A., Shapiro, R. A., Oldham, A. N., Duong, V. V., Martin, R. W. (2010). Pneumatic switched angle spinning NMR probe with capacitively coupled double saddle coil. Journal of Magnetic Resonance. 206(2), 183-189.
Shapiro, R. A., Brindley, A. J., Martin, R. W. (2010). Thermal Stabilization of DMPC/DHPC Bicelles by Addition of Cholesterol Sulfate. J. Am. Chem. Soc., 132(33), 11406-11407.
Franck, J. M., Demas, V., Martin, R. W., Bouchard, L. S. (2009). Shimmed matching pulses: Simultaneous control of rf and static gradients for inhomogeneity correction. J. Chem. Phys., 131, 234506.
Donovan, K. J., Allen, M. A., Martin, R. W., Shaka, A. J. (2009). Sensitive, quantitative carbon-13 NMR spectra by mechanical sample translation. Journal of Magnetic Resonance, 197, 237-241.
Ferreira, T. M., Medronho, B., Martin, R. W., Topgaard, D. (2009). Segmental order parameters in a nonionic surfactant lamellar phase studied with 1H-13C solid-state NMR. Phys. Chem. Chem. Phys., 10, 6033-6038.
Qian, C., Thureau, P., Martin, R. W. (2008). Variable angle spinning (VAS) experiments for strongly oriented systems: methods development and preliminary results. Magnetic Resonance in Chemistry, 46, 351-355.
Qian, C., Pines, A., Martin, R. W. (2007). Design and construction of a contactless mobile RF coil for double resonance Variable Angle Spinning NMR. Journal of Magnetic Resonance, 188, 183-189.
Jachmann, R. C., Trease, D. R., Bouchard, L. S., Sakellariou, D., Martin, R. W., Schlueter, R. D., Budinger, T. F., Pines, A. (2007). Multipole shimming of permanent magnets using harmonic corrector rings. Rev. Sci. Inst., 78, 035115.
R. W. Martin, R. C. Jachmann, D. Sakellariou, U. G. Nielsen, and A. Pines, "High-resolution NMR spectroscopy of biological tissues using projected magic angle spinning," Magnetic Resonance in Medicine 54; 253-257 (2005).
D. Sakellariou, C. A. Meriles, R. W. Martin, and A. Pines, "NMR in rotating magnetic fields: Magic angle field spinning," Magnetic Resonance Imaging 23 (2); 295-299 (2005).
T. I. Igumenova, A. E. McDermott, K. W. Zilm, R. W. Martin, E. K. Paulson, and A. J. Wand, "Assignments of carbon NMR resonances for microcrystalline ubiquitin," J. Am. Chem. Soc. 126 (21); 6720-6727 (2004).
A. G. Shahkhatuni, A. A. Shakhatuni, H. A. Panosyan, G. H. J. Park, R. W. Martin, and A. Pines, "NMR studies of 13C-iodomethane: Different behavior in thermotropic and lyotropic liquid crystals," J. Phys. Chem. A 108 (33); 6809-6813 (2004).
C. Leal, D. Topgaard, R. W. Martin, and H. Wennerstrom, "NMR studies of molecular mobility in a DNA-amphiphile complex," J. Phys. Chem. B 108; 15392-15397 (2004).
G. H. J. Park, R. W. Martin, D. Sakellariou, A. Pines, A. G. Shahkhatuni, A. A. Shakhatuni, and H. A. Panosyan, "Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of 13C-iodomethane," Chem. Phys. Lett. 399; 196-199 (2004).
E. K. Paulson, R. W. Martin, and K. W. Zilm, "Cross-polarization, radio-frequency field homogeneity, and circuit balancing in high-field solid-state NMR probes," Journal of Magnetic Resonance 171; 314-323 (2004).
D. Topgaard, R. W. Martin, D. Sakellariou, C. A. Meriles, and A. Pines, "NMR spectroscopy in an inhomogeneous magnetic field using 'shim pulses'," Proc. Natl. Acad. Sci. USA 101 (51); 17576-17581 (2004).
R. W. Martin and K. W. Zilm, "Variable temperature system using vortex tube cooling and fiber optic temperature sensor for low temperature magic angle spinning NMR," Journal of Magnetic Resonance 168; 202-209 (2004).
D. Sakellariou., C. A. Meriles, R. W. Martin, and A. Pines, "High-resolution NMR of anisotropic samples with spinning away from the magic angle," Chem. Phys. Lett. 377; 333-339 (2003).
R. W. Martin and K. W. Zilm, "Preparation of protein nanocrystals and their characterization by solid-state NMR," Journal of Magnetic Resonance 165; 162-174 (2003).
R. W. Martin, E. K. Paulson, and K. W. Zilm, "Design of a triple resonance magic angle sample spinning probe for high field solid-state nuclear magnetic resonance," Review of Scientific Instruments 74(6); 3045-3061 (2003).
A. McDermott, T. Polenova, A. Bockmann, K. W. Zilm, E. K. Paulson., R. W. Martin, and G. T. Montelione, "Partial NMR assignments for uniformly 13C-15N-enriched BPTI in the solid state," Journal of Biomolecular NMR. 16; 209-219 (2000).