Dual function C-terminal domain of dynamin-1: modulation of self-assembly by interaction of the assembly site with SH3 domains

Impairment of endocytosis by mutational targeting of dynamin-1 GTPases can result in paralysis and embryonic lethality. Dynamin-1 assembles at coated pits where it functions to cleave vesicles from donor membranes. Receptor endocytosis is modulated by SH3 (Src homology 3) domain proteins, which directly bind to Dynamin C-terminal proline motif sequences, affecting both the Dynamin GTPase activity and its recruitment to coated pits. We have determined that dynamin-dynamin interactions, which are required for Dynamin helix formation, involve these same SH3 domain-binding C-terminal proline motif sequences. Consequently, SH3 domain proteins induce the in vitro disassembly of Dynamin helices. Our results therefore suggest the the dual function of the Dynamin C-terminus (involving Amino acids 800-840) permits direct regulation of Dynamin assembly and function through interaction with SH3 domain proteins. Additionally, the N-terminal GTPase domain plays an important role in assembly. Finally, we show that the central PH (pleckstrin homology) domain exerts a strong inhibitory effect on the capacity for dynamin-1 self-assembly.