Chemistry Seminar with Professor Tatyana Polenova from the University of Delaware at 4pm

Abstract: 

NMR spectroscopy is a premier methodology for studying a wide array of naturally occurring and manmade systems and is unprecedented in the information content it provides. Yet, the notoriously low sensitivity of NMR is a main limitation that restricts its capacity to probe structures, dynamics, interactions and mechanisms in complex environments, such as those present in cells or at interfaces and surfaces in multi-component systems. In this seminar, I will discuss our recent efforts to establish next-generation magnetic resonance methods that overcome sensitivity as well as resolution bottlenecks in atomic-level characterization of large biological assemblies, manmade materials and pharmaceutical formulations at natural abundance, and proteins in their natural cellular milieus. To study these systems, we integrate magic angle spinning (MAS) NMR and dynamic nuclear polarization (DNP). I will first present MAS NMR methodologies designed to yield large sensitivity and resolution enhancements with 1H and 19F detection at high MAS frequencies (62-111 kHz) and permit efficient recoupling of dipolar and chemical shift anisotropies. With these experiments at hand, we have determined structures and dynamics of microtubule-associated protein assemblies with polymerized microtubules, microcrystalline proteins, and protein-ligand complexes. I will next introduce 19F DNP-enhanced MAS NMR spectroscopy in protein assemblies and proteins in mammalian cells. I will demonstrate that with very large, 35-100-fold signal enhancements afforded by these experiments, high signal-to-noise ratio MAS NMR spectra on nanomole-quantities of proteins in cells can be recorded in only minutes, and two-dimensional dipolar correlation spectra with remarkable resolution are obtained. This work paves the way for 19F DNP-enhanced MAS NMR applications in cellular milieus, for probing protein structure, dynamics and ligand interactions in native-like environments. I will then demonstrate the power of integrating MAS NMR with medium-resolution cryo-EM and data-driven MD simulations to gain comprehensive insights into the structure and dynamics of HIV-1 protein assemblies and connect these to function.