Abstract
Drp1 is a dynamin-like GTPase that mediates mitochondrial and peroxisomal division in a process dependent on self-assembly and coupled to GTP hydrolysis. Despite the link between Drp1 malfunction and human disease, the molecular details of its membrane activity remain poorly understood. Here we reconstituted and directly visualized Drp1 activity in giant unilamellar vesicles. We quantified the effect of lipid composition and GTP on membrane binding and remodeling activity by fluorescence confocal microscopy and flow cytometry. In contrast to other dynamin relatives, Drp1 bound to both curved and flat membranes even in the absence of nucleotides. We also found that Drp1 induced membrane tubulation that was stimulated by cardiolipin. Moreover, Drp1 promoted membrane tethering dependent on the intrinsic curvature of the membrane lipids and on GTP. Interestingly, Drp1 concentrated at membrane contact surfaces and, in the presence of GTP, formed discrete clusters on the vesicles. Our findings support a role of Drp1 not only in the formation of lipid tubes but also on the stabilization of tightly apposed membranes, which are intermediate states in the process of mitochondrial fission.
Highlights
Drp1 mediates mitochondrial division via a poorly understood mechanism
To determine whether this is the case for our purified Drp1, GTPase reactions were measured in the absence or presence of MLL large unilamellar vesicles (LUVs), which mimic the lipid composition of the mitochondrial outer membrane
When we quantified the number of tubes produced in giant unilamellar vesicles (GUVs) samples of the different lipid compositions, we found that Drp1-Al488 produced more lipid tubes in CLcontaining vesicles compared with phosphatidic acid (PA)-containing ones, suggesting that Drp1-induced membrane tubulation is not exclusively mediated by the negative curvature of the lipid (Fig. 2C)
Summary
Drp mediates mitochondrial division via a poorly understood mechanism. Results: Drp promotes giant vesicle tethering and concentrates at contact sites in structures similar to those found in dividing mitochondria. Drp is a dynamin-like GTPase that mediates mitochondrial and peroxisomal division in a process dependent on self-assembly and coupled to GTP hydrolysis. Our findings support a role of Drp in the formation of lipid tubes and on the stabilization of tightly apposed membranes, which are intermediate states in the process of mitochondrial fission. Despite the identification of new mediators involved in mitochondrial fission, the molecular details of how Drp itself mediates membrane division in either mitochondria or peroxisomes remain poorly understood. Drp induced the formation of lipid tubes depending on protein concentration, where cardiolipin seemed to be a potent stimulator These findings are in agreement with the proposed constriction activity of Drp on mitochondrial membranes. Drp promoted vesicle tethering and concentrated at the membrane contact sites, which are structural intermediates in the molecular pathway of membrane division likely involving non-lamellar lipid arrangements. Our findings support a molecular mechanism by which Drp promotes membrane fission by stabilizing membrane topologies involved in membrane fission
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
