Shiga toxin-converting bacteriophages play a critical role in the emergence and virulence of pathogenic Escherichia coli strains. Despite their significance, detailed structural information on these phages remains scarce. Here we present a high-resolution cryo-electron microscopy and proteomic analysis of the phi24B bacteriophage, revealing an icosahedral capsid with T=9 symmetry, decorated by a processed esterase protein (gp84) and stabilized by cementing proteins. The tail assembly comprises a dodecameric portal, two rings of adapter proteins sharing a common fold, a hexameric nozzle, six lateral tail fibers, and a flexible central needle fiber. The binding sites of the fibers are described. Comparative analysis indicates conservation of the tail structure with related podoviruses but very different peripheral features.
The Central Coupler of the AAA+ ATPase ClpXP Controls Intersubunit Communication and Couples the Conversion of Chemical Energy into the Generation of Force
ClpX is a clockwise hexameric helical arrangement that hydrolyzes ATP to unfold proteins and translocate them into the proteolytic chamber. We investigate the central coupler,