Cryo-Electron Microscopy Applications

Neurodegenerative diseases encompass a broad range of neurological disorders characterized by the progressive dysfunction and degradation of neurons in the central nervous system. This includes well-known pathologies such as Alzheimer’s, Parkinson’s, and Huntington’s Disease as well as Amyotrophic Lateral Sclerosis (ALS). While the physical manifestation of these diseases has been extensively observed and characterized, the molecular basis is still an area of active investigation. By using structural biology, researchers have begun to unravel the molecular changes that lead to neurological disorder – these efforts, in turn, drive the development of therapeutics that can slow or stop the course of disease.

In recent years, cryo-EM technology has improved dramatically, enabling the characterization of large sample areas and macromolecular proteins. This is particularly important for neurodegenerative disease research, where disorders are often characterized by the agglomeration and precipitation of complex protein aggregates. Researchers have already utilized cryo-EM to uncover the atomic structures of numerous proteins associated with neurodegenerative diseases such as tau filaments, ɑ-synuclein fibrils, and amyloid ß aggregates, as well as small molecule drug candidates that bind to these structures.

In general, protein structure and function correlate. By understanding the structural features of the protein aggregates implicated in neurodegenerative diseases, scientists can address how they form, interact with the cellular environment, and alter brain function. Membrane proteins and large macromolecular structures are challenging targets for X-ray crystallography and NMR spectroscopy (e.g., while membrane proteins account for over 60% of drug targets, they only make up ~2% of existing crystal structures). Cryo-EM techniques, meanwhile, do not require crystal growth, making them more flexible and capable of determining the structures of non-crystalline proteins. With cryo-EM, researchers can analyze the complex conformations, structures, and modified forms of proteins; multiple conformations can even be studied within a single sample.

Cryo-EM techniques help examine a broad range of biological structures and provides the ability to visualize otherwise difficult or complicated biologics. For example, protein samples, which are frozen in vitreous (non-crystalline) ice, can be examined in a near-native, fully hydrated state, thereby enabling accelerated structural drug discovery. Near-atomic resolution cryo-electron microscopy can be employed throughout the drug discovery process, from target identification, through lead characterization, to epitope mapping.