Mammalian Homologue NME3 of DYNAMO1 Regulates Peroxisome Division.

Peroxisomes proliferate by sequential processes comprising elongation, constriction, and scission of peroxisomal membrane. It is known that the constriction step is mediated by a GTPase named dynamin-like protein 1 (DLP1) upon efficient loading of GTP. However, mechanism of fuelling GTP to DLP1 remains unknown in mammals. We earlier show that nucleoside diphosphate (NDP) kinase-like protein, termed dynamin-based ring motive-force organizer 1 (DYNAMO1), generates GTP for DLP1 in a red alga, Cyanidioschyzon merolae. In the present study, we identified that nucleoside diphosphate kinase 3 (NME3), a mammalian homologue of DYNAMO1, localizes to peroxisomes. Elongated peroxisomes were observed in cells with suppressed expression of NME3 and fibroblasts from a patient lacking NME3 due to the homozygous mutation at the initiation codon of NME3. Peroxisomes proliferated by elevation of NME3 upon silencing the expression of ATPase family AAA domain containing 1, ATAD1. In the wild-type cells expressing catalytically-inactive NME3, peroxisomes were elongated. These results suggest that NME3 plays an important role in peroxisome division in a manner dependent on its NDP kinase activity. Moreover, the impairment of peroxisome division reduces the level of ether-linked glycerophospholipids, ethanolamine plasmalogens, implying the physiological importance of regulation of peroxisome morphology.

Onsite GTP fuelling via DYNAMO1 drives division of mitochondria and peroxisomes.

Mitochondria and peroxisomes proliferate by division. During division, a part of their membrane is pinched off by constriction of the ring-shaped mitochondrial division (MD) and peroxisome-dividing (POD) machinery. This constriction is mediated by a dynamin-like GTPase Dnm1 that requires a large amount of GTP as an energy source. Here, via proteomics of the isolated division machinery, we show that the 17-kDa nucleoside diphosphate kinase-like protein, dynamin-based ring motive-force organizer 1 (DYNAMO1), locally generates GTP in MD and POD machineries. DYNAMO1 is widely conserved among eukaryotes and colocalizes with Dnm1 on the division machineries. DYNAMO1 converts ATP to GTP, and disruption of its activity impairs mitochondrial and peroxisomal fissions. DYNAMO1 forms a ring-shaped complex with Dnm1 and increases the magnitude of the constricting force. Our results identify DYNAMO1 as an essential component of MD and POD machineries, suggesting that local GTP generation in Dnm1-based machinery regulates motive force for membrane severance.