STRUCTURE OF A CAPSID ASSEMBLY BY 1H-DETECTED MAS NMR
Protein structure determination is key to the detailed description of many biological processes. The critical factor that would allow general application of magic-angle spinning (MAS) solid-state NMR to this end is improvement in sensitivity and resolution for as many nuclear spins as possible. This was achieved at the CRMN with the detection of resolved 1H resonances in protonated proteins by increasing MAS rates to frequencies of 100 kHz and above. For large proteins and assemblies, ultrafast spinning narrows spectral resonances better than Brownian motion on which solution NMR relies, removing a fundamental barrier to the NMR study of large systems. This was exploited in a milestone publication to determine the de novo structure of a 28-kDa protein dimer in a 2.5-MDa viral capsid assembly.
STRUCTURE OF A SURFACE SITE BY DNP-SENS NMR
The ability to detect and characterize the three-dimensional (3D) structure of molecules at the atomic scale, through the introduction of a range of physical methods, has transformed molecular, biological and materials science over the past 50 years. However, if the species of interest is located on a surface, structure determination has so far not been possible. In this context, the demonstration that the full 3D structure of a Pt complex anchored on an amorphous silica surface could be determined by DNP SENS has been landmark achievement. The 200-fold increase in the NMR sensitivity of the surface fragment provided by DNP enabled the implementation of a series of multidimensional and multi-nuclear NMR correlation experiments providing quantitative structural restraints. Several 13C-15N and 29Si-15N distances were obtained under rotational echo double resonance (REDOR) experiments. The result, in combination with EXAFS, was a detailed structure for the surface complex, determined with a precision of 0.71 Å.
DEVELOPMENT OF NMR METHODS FOR FRAGMENT-BASED DRUG DISCOVERY
We are developing NMR methods for drug discovery, more particularly fragment-based drug discovery. In particular, we are developing approaches for fragment screening against membrane proteins, especially the GPCR family. While GPCR are currently the most targeted proteins by drugs on the market, there is a huge therapeutic potential for this family of proteins and therefore the necessity to develop methods to identify allosteric ligands. We are also interested in NMR-based strategies that will facilitate or accelerate fragment to hit development, using either labelled and unlabelled protein samples.
With the CRCL, we are developing molecules, as anti-cancer therapeutics, or as chemical probes to better understand the biological pathways involved in cancer.
Hyperpolarization by dissolution dynamic nuclear polarization has made ultra-sensitive magnetic resonance become a reality and has triggered the development of a plethora of promising applications in spectroscopy and imaging. Unfortunately, some severe limitations severely restrain the widespread use of this method, amongst which the experimental complexity, the need for trained personnel, and the exuberant price. We are developing solutions for a broad democratization of hyperpolarization by enabling transport over long distances, so as to bring molecules directly in a hyperpolarized state at the point of use. We have recently pioneered a new concept in which transport was demonstrated in some micro-crystalline formulated 13C-labelled molecules (see for example here the extension of the lifetime of hyperpolarized pyruvate from minutes to tens of hours). We are currently working on a new approach where arbitrary molecules, with arbitrary formulations (ranging from crystals to glass and frozen solutions), can be equally hyperpolarized at state-of-the-art levels exceeding P(13C) > 40%, and further stored for hours in view of transport to a remote point of use.
NEW METHODS FOR CONFORMATIONAL DYNAMICS OF BIOMOLECULES
Describing conformational plasticity of biomolecules is essential to understand their detailed biophysics and connect it to their biological function. However, the complexity of these processes often prevents such descriptions. We actively developed novel experimental and computational methods, both for RNA or proteins to access the description to those key biophysical processes. In particular, we described how a chaperone protein can dynamically perturb the conformational landscape of its substrate to trigger its folding in absence of external source of energy.