Little evidence that FAM65B belongs to the family of phox homology (PX) and bin/amphiphysin/rvs (BAR) domain-containing proteins.
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ABSTRACT:
SUBMITTER: Teasdale RD
PROVIDER: S-EPMC4191800 | biostudies-literature | 2014 Sep
REPOSITORIES: biostudies-literature
Publications
Little evidence that FAM65B belongs to the family of phox homology (PX) and bin/amphiphysin/rvs (BAR) domain-containing proteins.
Teasdale Rohan D RD Collins Brett M BM
Proceedings of the National Academy of Sciences of the United States of America 20140919 39
Similar Datasets
Project description:We provide direct evidence that Bin/Amphiphysin/Rvs (BAR) family members bend the steady state membrane architecture of organelles in intact cells. In response to inducible BAR molecular actuators, organelles exhibit distinct changes to the orientation and degree of their membrane curvature. This rapidly inducible system may offer a mechanism by which to better understand the structure-function relationship of intracellular organelles.
| S-EPMC4894391 | biostudies-literature
Project description:Bin/Amphiphysin/Rvs (BAR) domain-containing proteins are essential players in the dynamics of intracellular compartments. The BAR domain is an evolutionarily conserved dimeric module characterized by a crescent-shaped structure whose intrinsic curvature, flexibility, and ability to assemble into highly ordered oligomers contribute to inducing the curvature of target membranes. Endophilins, diverging into A and B subgroups, are BAR and SH3 domain-containing proteins. They exert activities in membrane dynamic processes such as endocytosis, autophagy, mitochondrial dynamics, and permeabilization during apoptosis. Here, we report on the involvement of the third α-helix of the endophilin A BAR sequence in dimerization and identify leucine 215 as a key residue within a network of hydrophobic interactions stabilizing the entire BAR dimer interface. With the combination of N-terminal truncation retaining the high dimerization capacity of the third α-helices of endophilin A and leucine 215 substitution by aspartate (L215D), we demonstrate the essential role of BAR sequence-mediated dimerization on SH3 domain partnership. In comparison with wild type, full-length endophilin A2 heterodimers with one protomer bearing the L215D substitution exhibit very significant changes in membrane binding and shaping activities as well as a dramatic decrease of SH3 domain partnership. This suggests that subtle changes in the conformation and/or rigidity of the BAR domain impact both the control of membrane curvature and downstream binding to effectors. Finally, we show that expression, in mammalian cells, of endophilin A2 bearing the L215D substitution impairs the endocytic recycling of transferrin receptors.
| S-EPMC3281743 | biostudies-literature
Project description:Proteins of the Bin/amphiphysin/Rvs (BAR) domain superfamily are essential in controlling the shape and dynamics of intracellular membranes. Here, we present evidence for the unconventional function of a member of the endophilin family of BAR and Src homology 3 domain-containing proteins, namely endophilin B2, in the perinuclear organization of intermediate filaments. Using mass spectrometry analysis based on capturing endophilin B2 partners in in situ pre-established complexes in cells, we unravel the interaction of endophilin B2 with plectin 1, a variant of the cytoskeleton linker protein plectin as well as with vimentin. Endophilin B2 directly binds the N-terminal region of plectin 1 via Src homology 3-mediated interaction and vimentin indirectly via plectin-mediated interaction. The relevance of these interactions is strengthened by the selective and drastic reorganization of vimentin around nuclei upon overexpression of endophilin B2 and by the extensive colocalization of both proteins in a meshwork of perinuclear filamentous structures. By generating mutants of the endophilin B2 BAR domain, we show that this phenotype requires the BAR-mediated membrane binding activity of endophilin B2. Plectin 1 or endophilin B2 knockdown using RNA interference disturbed the perinuclear organization of vimentin. Altogether, these data suggest that the endophilin B2-plectin 1 complex functions as a membrane-anchoring device organizing and stabilizing the perinuclear network of vimentin filaments. Finally, we present evidence for the involvement of endophilin B2 and plectin 1 in nuclear positioning in individual cells. This points to the potential importance of the endophilin B2-plectin complex in the biological functions depending on nuclear migration and positioning.
| S-EPMC3779758 | biostudies-literature
Project description:Control of membrane curvature is required in many important cellular processes, including endocytosis and vesicular trafficking. Endophilin is a bin/amphiphysin/rvs (BAR) domain protein that induces vesicle formation by promotion of membrane curvature through membrane binding as a dimer. Using site-directed spin labeling and EPR spectroscopy, we show that the overall BAR domain structure of the rat endophilin A1 dimer determined crystallographically is maintained under predominantly vesiculating conditions. Spin-labeled side chains on the concave surface of the BAR domain do not penetrate into the acyl chain interior, indicating that the BAR domain interacts only peripherally with the surface of a curved bilayer. Using a combination of EPR data and computational refinement, we determined the structure of residues 63-86, a region that is disordered in the crystal structure of rat endophilin A1. Upon membrane binding, residues 63-75 in each subunit of the endophilin dimer form a slightly tilted, amphipathic alpha-helix that directly interacts with the membrane. In their predominant conformation, these helices are located orthogonal to the long axis of the BAR domain. In this conformation, the amphipathic helices are positioned to act as molecular wedges that induce membrane curvature along the concave surface of the BAR domain.
| S-EPMC2888429 | biostudies-literature
Project description:The process of membrane curvature generation by BAR (Bin/amphiphysin/Rvs) domains is thought to involve the plastering of the negatively charged cell membrane to the positively charged concave surface of the BAR domain. Recent work [Peter, B. J., et al. (2004) Science, 303,495-499; Masuda, M., et al. (2006) EMBO J. 25, 2889-2897; and Gallop, J. L., et al. (2006) EMBO J. 25, 2898-2910] has demonstrated the importance of the charged, crescent-shaped surface and the N-terminal amphipathic helices (present in N-BAR domains) for generating membrane curvature. These experiments suggest that curvature is generated by the synergistic action of the N-terminal helices embedding in the lipid bilayer and the charged crescent-shaped dimer acting to "scaffold" membrane curvature. Here, we present atomistic molecular dynamics simulations that directly show membrane binding to the concave face of N-BAR domains, resulting in the generation of local membrane curvature that matches the curvature presented by the BAR domain. These simulations provide direct molecular-scale evidence that BAR domains create curvature by acting as a scaffold, forcing the membrane to locally adopt the intrinsic shape of the BAR domain. We find that BAR domains bind strongly through the maximum curvature surface and, additionally, at an orientation that presents a lesser degree of curvature, thus enabling N-BAR domains to induce a range of local curvatures. Finally, we find that the N-terminal region may play a role in biasing the orientations of N-BAR domains on the membrane surface to those that favor binding to the concave face and subsequent membrane bending.
| S-EPMC1622778 | biostudies-literature
Project description:Dynamin mediates various membrane fission events, including the scission of clathrin-coated vesicles. Here, we provide direct evidence for cooperative membrane recruitment of dynamin with the BIN/amphiphysin/Rvs (BAR) proteins, endophilin and amphiphysin. Surprisingly, endophilin and amphiphysin recruitment to membranes was also dependent on binding to dynamin due to auto-inhibition of BAR-membrane interactions. Consistent with reciprocal recruitment in vitro, dynamin recruitment to the plasma membrane in cells was strongly reduced by concomitant depletion of endophilin and amphiphysin, and conversely, depletion of dynamin dramatically reduced the recruitment of endophilin. In addition, amphiphysin depletion was observed to severely inhibit clathrin-mediated endocytosis. Furthermore, GTP-dependent membrane scission by dynamin was dramatically elevated by BAR domain proteins. Thus, BAR domain proteins and dynamin act in synergy in membrane recruitment and GTP-dependent vesicle scission.
| S-EPMC3585104 | biostudies-literature
Project description:Cellular proteins containing Bin/amphiphysin/Rvs (BAR) domains play a key role in clathrin-mediated endocytosis. Despite extensive structural and functional studies of BAR domains, it is still unknown how exactly these domains interact with the plasma membrane containing phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) and whether they function by a universal mechanism or by different mechanisms. Here we report that PtdIns(4,5)P(2) specifically induces partial membrane penetration of the N-terminal amphiphilic α-helix (H(0)) of two representative N-BAR domains from Drosophila amphiphysin (dAmp-BAR) and rat endophilin A1 (EndoA1-BAR). Our quantitative fluorescence imaging analysis shows that PtdIns(4,5)P(2)-dependent membrane penetration of H(0) is important for self-association of membrane-bound dAmp-BAR and EndoA1-BAR and their membrane deformation activity. EndoA1-BAR behaves differently from dAmp-BAR because the former has an additional amphiphilic α-helix that penetrates the membrane in a PtdIns(4,5)P(2)-independent manner. Depletion of PtdIns(4,5)P(2) from the plasma membrane of HEK293 cells abrogated the membrane deforming activity of EndoA1-BAR and dAmp-BAR. Collectively, these studies suggest that the local PtdIns(4,5)P(2) concentration in the plasma membrane may regulate the membrane interaction and deformation by N-BAR domain-containing proteins during clathrin-mediated endocytosis.
| S-EPMC3464517 | biostudies-literature
Project description:Membrane-sculpting BAR (Bin/Amphiphysin/Rvs) domains form a crescent-shaped homodimer that can sense and induce membrane curvature through its positively charged concave face. We have recently shown that Arfaptin-2, which was originally identified as a binding partner for the Arf and Rac1 GTPases, binds to Arl1 through its BAR domain and is recruited onto Golgi membranes. There, Arfaptin-2 induces membrane tubules. Here, we report the crystal structure of the Arfaptin-2 BAR homodimer in complex with two Arl1 molecules bound symmetrically to each side, leaving the concave face open for membrane association. The overall structure of the Arl1·Arfaptin-2 BAR complex closely resembles that of the PX-BAR domain of sorting nexin 9, suggesting similar mechanisms underlying BAR domain targeting to specific organellar membranes. The Arl1·Arfaptin-2 BAR structure suggests that one of the two Arl1 molecules competes with Rac1, which binds to the concave face of the Arfaptin-2 BAR homodimer and may hinder its membrane association.
| S-EPMC3408144 | biostudies-literature
Project description:Transverse tubules (t-tubules) regulate cardiac excitation-contraction coupling and exhibit interchamber and interspecies differences in expression. In cardiac disease, t-tubule loss occurs and affects the systolic calcium transient. However, the mechanisms controlling t-tubule maintenance and whether these factors differ between species, cardiac chambers, and in a disease setting remain unclear.To determine the role of the Bin/Amphiphysin/Rvs domain protein amphiphysin II (AmpII) in regulating t-tubule maintenance and the systolic calcium transient.T-tubule density was assessed by di-4-ANEPPS, FM4-64 or WGA staining using confocal microscopy. In rat, ferret, and sheep hearts t-tubule density and AmpII protein levels were lower in the atrium than in the ventricle. Heart failure (HF) was induced in sheep using right ventricular tachypacing and ferrets by ascending aortic coarctation. In both HF models, AmpII protein and t-tubule density were decreased in the ventricles. In the sheep, atrial t-tubules were also lost in HF and AmpII levels decreased. Conversely, junctophilin 2 levels did not show interchamber differences in the rat and ferret nor did they change in HF in the sheep or ferret. In addition, in rat atrial and sheep HF atrial cells where t-tubules were absent, junctophilin 2 had sarcomeric intracellular distribution. Small interfering RNA-induced knockdown of AmpII protein reduced t-tubule density, calcium transient amplitude, and the synchrony of the systolic calcium transient.AmpII is intricately involved in t-tubule maintenance. Reducing AmpII protein decreases t-tubule density, reduces the amplitude, and increases the heterogeneity of the systolic calcium transient.
| S-EPMC4274343 | biostudies-literature
Project description:ArfGAP With Coiled-Coil, Ankyrin Repeat And PH Domains 4 (ACAP4) is an ADP-ribosylation factor 6 (ARF6) GTPase-activating protein essential for EGF-elicited cell migration. However, how ACAP4 regulates membrane dynamics and curvature in response to EGF stimulation is unknown. Here, we show that phosphorylation of the N-terminal region of ACAP4, named the Bin, Amphiphysin, and RSV161/167 (BAR) domain, at Tyr34 is necessary for EGF-elicited membrane remodeling. Domain structure analysis demonstrates that the BAR domain regulates membrane curvature. EGF stimulation of cells causes phosphorylation of ACAP4 at Tyr34, which subsequently promotes ACAP4 homodimer curvature. The phospho-mimicking mutant of ACAP4 demonstrates lipid-binding activity and tubulation in vitro, and ARF6 enrichment at the membrane is associated with ruffles of EGF-stimulated cells. Expression of the phospho-mimicking ACAP4 mutant promotes ARF6-dependent cell migration. Thus, the results present a previously undefined mechanism by which EGF-elicited phosphorylation of the BAR domain controls ACAP4 molecular plasticity and plasma membrane dynamics during cell migration.
| S-EPMC3703971 | biostudies-literature