F-BAR Proteins of the Syndapin Family Shape the Plasma Membrane and Are Crucial for Neuromorphogenesis

Membrane remodeling by Fes/Cip4 homology-Bin/Amphiphysin/Rvs167 (F-BAR) proteins is regulated by autoinhibitory interactions between their SRC homology 3 (SH3) and F-BAR domains. The structural basis of autoregulation, and whether it affects interactions of SH3 domains with other cellular ligands, remain unclear. Here we used single-particle electron microscopy to determine the structure of the F-BAR protein Nervous Wreck (Nwk) in both soluble and membrane-bound states. On membrane binding, Nwk SH3 domains do not completely dissociate from the F-BAR dimer, but instead shift from its concave surface to positions on either side of the dimer. Unexpectedly, along with controlling membrane binding, these autoregulatory interactions inhibit the ability of Nwk-SH3a to activate Wiskott–Aldrich syndrome protein (WASp)/actin related protein (Arp) 2/3-dependent actin filament assembly. In Drosophila neurons, Nwk autoregulation restricts SH3a domain-dependent synaptopod formation, synaptic growth, and actin organization. Our results define structural rearrangements in Nwk that control F-BAR–membrane interactions as well as SH3 domain activities, and suggest that these two functions are tightly coordinated in vitro and in vivo.

Section: Resultsmentioning

confidence: 99%

Coordinated autoinhibition of F-BAR domain membrane binding and WASp activation by Nervous Wreck

Stanishneva‐Konovalova

Kelley

Eskin

et al. 2016

“…Syndapin family members also are crucial regulators of notochord development (22) and neuromorphogenesis by linking membrane deformation to N-WASPdependent actin polymerization (28). We speculate that N-WASP binding to syndapin 1 SH3 (15) will cause conformational changes similar to those elicited by association of dynamin.…”

Section: Association Of Syndapin 1 With Dynamin 1 or A Dynamin 1-derimentioning

confidence: 95%

“…Thus, syndapin 1 and dynamin 1 appear to undergo a functional partnership in driving membrane remodeling during endocytosis. Discussion BAR domain superfamily proteins play a fundamental role in shaping membranes during diverse cellular processes (3) ranging from the formation of endocytic vesicles (5,10,17,24,25) and T tubules in muscle (26,27) to cell migration and morphogenesis (16,22,28,29). Previous studies have allowed us a glimpse at the molecular mechanisms by which BAR/F-BAR domain proteins drive membrane bending (4,5) or sense and stabilize curved membrane domains (1,7).…”

Section: Association Of Syndapin 1 With Dynamin 1 or A Dynamin 1-derimentioning

confidence: 99%

“…We speculate that N-WASP binding to syndapin 1 SH3 (15) will cause conformational changes similar to those elicited by association of dynamin. Interestingly, during neuromorphogenesis, syndapin 1 appears to release N-WASP from autoinhibition (28). Hence, syndapin 1 action during actin-dependent remodeling of the neuronal plasma membrane and bulk endocytosis (17) may follow similar regulatory principles.…”

Section: Association Of Syndapin 1 With Dynamin 1 or A Dynamin 1-derimentioning

confidence: 99%

See 1 more Smart Citation

Molecular basis for SH3 domain regulation of F-BAR–mediated membrane deformation

Rao

Vahedi-Faridi

et al. 2010

143

183

Members of the Bin/amphiphysin/Rvs (BAR) domain protein superfamily are involved in membrane remodeling in various cellular pathways ranging from endocytic vesicle and T-tubule formation to cell migration and neuromorphogenesis. Membrane curvature induction and stabilization are encoded within the BAR or Fer-CIP4 homology-BAR (F-BAR) domains, α-helical coiled coils that dimerize into membrane-binding modules. BAR/F-BAR domain proteins often contain an SH3 domain, which recruits binding partners such as the oligomeric membrane-fissioning GTPase dynamin. How precisely BAR/F-BAR domain-mediated membrane deformation is regulated at the cellular level is unknown. Here we present the crystal structures of full-length syndapin 1 and its F-BAR domain. Our data show that syndapin 1 F-BAR-mediated membrane deformation is subject to autoinhibition by its SH3 domain. Release from the clamped conformation is driven by association of syndapin 1 SH3 with the proline-rich domain of dynamin 1, thereby unlocking its potent membrane-bending activity. We hypothesize that this mechanism might be commonly used to regulate BAR/F-BAR domain-induced membrane deformation and to potentially couple this process to dynamin-mediated fission. Our data thus suggest a structure-based model for SH3-mediated regulation of BAR/F-BAR domain function.

“…In neuromorphogenesis, Pacsin1 functions at the interface of endocytosis and membrane trafficking, acting as an adaptor to link membrane deformation via its F-BAR domain to vesicle internalization and trafficking via its SH3 domain (24,35). Also functioning in neurons, the phosphatase activity of Synaptojanin1 is crucial for phosphoinositide homeostasis and for the maintenance of a functional pool of synaptic vesicles (36).…”

Section: Discussionmentioning

confidence: 99%

Identification of neuronal substrates implicates Pak5 in synaptic vesicle trafficking

Strochlic

Concilio

Viaud

et al. 2012

Synaptic transmission is mediated by a complex set of molecular events that must be coordinated in time and space. While many proteins that function at the synapse have been identified, the signaling pathways regulating these molecules are poorly understood. Pak5 (p21-activated kinase 5) is a brain-specific isoform of the group II Pak kinases whose substrates and roles within the central nervous system are largely unknown. To gain insight into the physiological roles of Pak5, we engineered a Pak5 mutant to selectively radiolabel its substrates in murine brain extract. Using this approach, we identified two novel Pak5 substrates, Pacsin1 and Synaptojanin1, proteins that directly interact with one another to regulate synaptic vesicle endocytosis and recycling. Pacsin1 and Synaptojanin1 were phosphorylated by Pak5 and the other group II Paks in vitro, and Pak5 phosphorylation promoted Pacsin1-Synaptojanin1 binding both in vitro and in vivo. These results implicate Pak5 in Pacsin1-and Synaptojanin1-mediated synaptic vesicle trafficking and may partially account for the cognitive and behavioral deficits observed in group II Pak-deficient mice.