Pathogens have evolved sophisticated molecular strategies to colonize their hosts and establish persistent infections, and to evade the host’s defense mechanisms. In this molecular tug of war, many bacteria produce extracellular protein fibers to attach to host tissue, and to form highly resistant bacterial communities called biofilms. Some of these fibers share stunning structural similarities with toxic protein deposits found in human neurodegenerative diseases. Researches at the HZI analyze their structures, how bacteria can make them safely and use them for their own purposes.