EMBO J 31 10, 2249–2260 (2012); published online March 30 2012
Once thought to exist only in eukaryotic cells, the highly conserved bacterial cytoskeleton is now known to function analogously to its eukaryotic counterparts, particularly in cell shape and division. For instance, the actin-like MreB protein and its homologs are important to maintain cell shape in many rod-shaped bacteria, probably by organizing how peptidoglycan is synthesized. FtsZ, a tubulin homolog, forms a scaffold for the cytokinetic ring, or divisome, by GTP-dependent polymerization into protofilaments. In this issue of The EMBO Journal, Szwedziak et al (2012) reveal the first crystal structures of cell division protein FtsA polymerizing into actin-like filaments, along with in vivo evidence that this self-interaction is crucial for proper cell division.