A dramatic protein fold switch powers a bactericidal nanomachine.

ABSTRACT: Fold switching, where a protein region interconverts between entirely distinct three-dimensional structures, is emerging as vital for certain protein functions. Here, we report a remarkable example in the F7 pyocin, a phage tail-like bactericidal nanomachine. Cryogenic electron microscopy and tomography reveal that a 163-residue segment of the central tail fiber undergoes a dramatic transition-from a trimeric α-helical coiled-coil to a triangular β-prism-upon binding to the bacterial cell surface. This massive fold switch remodels the tail tip, ejects the internal tape measure protein, and drives membrane puncture. Site-directed mutations that selectively destabilize the β-prism conformation completely abolish bactericidal activity without impairing particle assembly, implying that the ene

SUBMITTER: He Y 

PROVIDER: S-EPMC12874032 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature