In situ structural biology allows us to study molecules in near-native conditions.

In situ is latin for “in place”; this is in contrast to how structural biology is done ex situ, on purified proteins or reconstituted complexes. When studying viruses, this can take on different meanings. Individual virions can be considered basic infectious units, so as long as they remain intact, their components can be considered in situ. During its life cycle, the viral machinery is operating within the cell, so in this context, within the cell would be considered in situ.

Structural biology within cells presents a number of challenges, including specimen thickness and difficulty finding regions of interested. In order to meet these challenges, we employ several multi-scale methods complementary to cryo-ET. In order to section cells to imageable thicknesses, we use cryo-focused ion beam (cryo-FIB) milling. To target regions of interest, we use correlative light and electron microscopy (CLEM). To effectively combine these methods, we aim to use cutting edge hardware and the develop the necessary software to best use the data.