For an organism to survive, its proteins must adopt a diversity of conformations in a challenging
environment where macromolecular crowding can derail even robust biological pathways. This
situation becomes critical when considering proteins with energetic folding landscapes that
permit many conformational states. In these cases, the environment can clearly influence the
conformation by favoring one pathway over another. Because the aggregating proteins that are
responsible for neurodegenerative diseases like Alzheimer’s and Parkinson’s diseases often
have identical sequences in healthy and diseased individuals, differences in cellular
environment are responsible for the conformational switch. Yet, despite the importance of the
environment for protein folding, structural investigations of biomolecules are typically confined to
in vitro systems, which cannot capture important structural features imposed by biological
environments. Solid-state NMR spectroscopy is currently undergoing a “sensitivity renaissance”
with the development of dynamic nuclear polarization (DNP). Experiments that would require
decades of experimental time with traditional ssNMR methods can be collected in a day with
DNP NMR. Moreover, while most structural biology approaches require purified samples, NMR
spectroscopy does not. Because NMR reports quantitatively on the relative populations - with
atomic level precision - it can report on the identity and relative abundance of structural
polymorphs. Here, we will capitalize on the methodology for in cell structural biology using DNP-
assisted NMR we have developed in our group to determine if and how biological settings
influence the conformations of both the highly ordered and intrinsically disordered regions with
atomic level precision.
