Advances in structure determination by cryo‐EM to unravel membrane‐spanning pore formation

The beta pore‐forming proteins (β‐PFPs) are a large class of polypeptides that are produced by all Kingdoms of life to contribute to their species' own survival. Pore assembly is a sophisticated multi‐step process that includes receptor/membrane recognition and oligomerization events, and is ensued by large‐scale structural rearrangements, which facilitate maturation of a prepore into a functional membrane spanning pore. A full understanding of pore formation, assembly, and maturation has traditionally been hindered by a lack of structural data; particularly for assemblies representing differing conformations of functional pores. However, recent advancements in cryo‐electron microscopy (cryo‐EM) techniques have provided the opportunity to delineate the structures of such flexible complexes, and in different states, to near‐atomic resolution. In this review, we place a particular emphasis on the use of cryo‐EM to uncover the mechanistic details including architecture, activation, and maturation for some of the prominent members of this family.