C. elegans dynamin-related protein DRP-1 controls severing of the mitochondrial outer membrane

Little is known about the mechanism of mitochondrial division. We show here that mitochondria are disrupted by mutations in a C. elegans dynamin-related protein (DRP-1). Mutant DRP-1 causes the mitochondrial matrix to retract into large blebs that are both surrounded and connected by tubules of outer membrane. This indicates that scission of the mitochondrial outer membrane is inhibited, while scission of the inner membrane still occurs. Overexpressed wild-type DRP-1 causes mitochondria to become excessively fragmented, consistent with an active role in mitochondrial scission. DRP-1 fused to GFP is observed in spots on mitochondria where scission eventually occurs. These data indicate that wild-type DRP-1 contributes to the final stages of mitochondrial division by controlling scission of the mitochondrial outer membrane.