Molecular 'knitting machine' for bacterial capsules mapped in 3D

Most bacteria, including many bacterial pathogens, are surrounded by an outer protective layer of sugar molecules, known as a capsule. This primarily protects the bacteria from environmental influences, but also serves as a kind of cloak of invisibility, enabling them to evade the phagocytes of our immune system. Structural biologists at the Helmholtz Center for Infection Research (HZI) have now used cryo-electron microscopy to visualize the central Wza-Wzc protein complex, with which sugar molecules pass from the interior of the bacterial cell to the outside, in three dimensions at the atomic level for the first time.