Filamentous actin destabilization by HO favors DnmA aggregation, with crucial roles of cysteines 450 and 776 in mitochondrial and peroxisomal division in .

Mitochondria constitute major sources of HO and other reactive oxygen species in eukaryotic cells. The division of these organelles is crucial for multiple processes in cell biology and relies on highly regulated mechano-GTPases that are oligomerization dependent and belong to the dynamin-related protein family, like DnmA. Our previous work demonstrated that HO induces mitochondrial constriction, division, and remodeling of the outer membrane. Here, we show that HO also induces a DnmA aggregation consistent with higher-order oligomerization and its recruitment to mitochondria. The study of this response uncovered that HO induces the depolymerization and reorganization of actin as well as the critical role that cysteines 450 and 776 play in DnmA function. Our results provide new insights into the mechanisms of reactive oxygen species cell signaling and how they can regulate the dynamics of the actin cytoskeleton and the division of mitochondria and peroxisomes.