Identification and function of conformational dynamics in the multidomain GTP ase dynamin

Abstract

Vesicle release upon endocytosis requires membrane fission, catalyzed by the large GTPase dynamin. Dynamin contains five domains that together orchestrate its mechanochemical activity. Hydrogen-deuterium exchange coupled with mass spectrometry revealed global nucleotide-and membrane-binding-dependent conformational changes, as well as the existence of an allosteric relay element in the a2 S helix of the dynamin stalk domain. As predicted from structural studies, FRET analyses detect large movements of the pleckstrin homology domain (PHD) from a 'closed' conformation docked near the stalk to an 'open' conformation able to interact with membranes. We engineered dynamin constructs locked in either the closed or open state by chemical cross-linking or deletion mutagenesis and showed that PHD movements function as a conformational switch to regulate dynamin self-assembly, membrane binding, and fission. This PHD conformational switch is impaired by a centronuclear myopathy-causing disease mutation, S619L, highlighting the physiological significance of its role in regulating dynamin function. Together, these data provide new insight into coordinated conformational changes that regulate dynamin function and couple membrane binding, oligomerization, and GTPase activity during dynamin-catalyzed membrane fission.

Cryo-EM Studies of Drp1 Reveal Cardiolipin Interactions that Activate the Helical Oligomer

“…Within this region, additional protein density was apparent (Fig. 1h , dotted orange hexagon), and we attribute this to VD interactions near the stalk, comparable to interactions between the PH domain and stalk of dynamin 37 . In this conformation, interactions between the VD and lipid would likely be transient, which is consistent with the weak membrane association.…”

Early and nonredundant functions of dynamin isoforms in clathrin-mediated endocytosis

“…, 2010 ) and also as a docking site for intramolecular regulation of dynamin assembly through PH domain interactions ( Kenniston and Lemmon, 2010 ; Reubold, Faelber, et al. , 2015 ; Srinivasan et al. , 2016 ), alterations in either or both functions could affect the lifetime and/or extent of dynamin interactions at CCPs.…”

Drp1 polymerization stabilizes curved tubular membranes similar to those of constricted mitochondria

“…According to this model, the GTPase domains in Drp1 oligomers are located on one side of the filament and opposite to the membrane, whereas the B-inserts face the membrane (Fröhlich et al, 2013). In contrast to classical dynamins, Drp1 does not contain a PH domain for membrane binding or curvature sensing and generation (Srinivasan et al, 2016). Instead, Drp1 includes a region known as a variable domain, whose function is still debated but has been related to membrane binding and negative regulation of cytosolic Drp1 assembly (Francy et al, 2015).…”