A bacterial dynamin-like protein

Dynamins form a superfamily of large mechano-chemical GTPases that includes the classical dynamins and dynamin-like proteins (DLPs)1. They are found throughout the Eukarya, functioning in core cellular processes such as endocytosis and organelle division1. Many bacteria are predicted by sequence to possess large GTPases with the same multidomain architecture that is found in DLPs2. Mechanistic dissection of dynamin family members has been impeded by a lack of high-resolution structural data currently restricted to the GTPase3,4 and pleckstrin homology5 domains, and the dynamin-related human guanylate-binding protein6. Here we present the crystal structure of a cyanobacterial DLP in both nucleotide-free and GDP-associated conformation. The bacterial DLP shows dynamin-like qualities, such as helical self-assembly and tubulation of a lipid bilayer. In vivo, it localizes to the membrane in a manner reminiscent of FZL7, a chloroplast-specific dynamin-related protein with which it shares sequence similarity. Our results provide structural and mechanistic insight that may be relevant across the dynamin superfamily. Concurrently, we show compelling similarity between a cyanobacterial and chloroplast DLP that, given the endosymbiotic ancestry of chloroplasts8, questions the evolutionary origins of dynamins.