13. Kelley, CF; Messelaar, EM; Eskin, TL; Wang, SY; Song, KK; Vishnia, K; Becalska, AN; Shupliakov, O; Hagan, MF; Danino, D; Sokolova, OS; Nicastro, D; Rodal, AA. (2015) Membrane Charge Directs the Outcome of F-BAR Domain Lipid Binding and Autoregulation.Cell Reports 13: 2597-2609 Membrane Charge Directs the Outcome of F-BAR Domain Lipid Binding and Autoregulation
F-BAR domain proteins regulate and sense membrane curvature by interacting with negatively charged phospholipids and assembling into higher-order scaffolds. However, regulatory mechanisms controlling these interactions are poorly understood. Here, we show that Drosophila Nervous Wreck (Nwk) is autoregulated by a C-terminal SH3 domain module that interacts directly with its F-BAR domain. Surprisingly, this autoregulation does not mediate a simple "on-off'' switch for membrane remodeling. Instead, the isolated Nwk F-BAR domain efficiently assembles into higher-order structures and deforms membranes only within a limited range of negative membrane charge, and autoregulation elevates this range. Thus, autoregulation could either reduce membrane binding or promote higher-order assembly, depending on local cellular membrane composition. Our findings uncover an unexpected mechanism by which lipid composition directs membrane remodeling. DOI PubMed
9.Becalska, AN; Kelley, CF; Berciu, C; Stanishneva-Konovalova, TB; Fu, XF; Wang, SY; Sokolova, OS; Nicastro, D; Rodal, AA. (2013) Formation of membrane ridges and scallops by the F-BAR protein Nervous Wreck.Mol. Biol. Cell 24: 2406-2418 Formation of membrane ridges and scallops by the F-BAR protein Nervous Wreck
Eukaryotic cells are defined by extensive intracellular compartmentalization, which requires dynamic membrane remodeling. FER/Cip4 homology-Bin/amphiphysin/Rvs (F-BAR) domain family proteins form crescent-shaped dimers, which can bend membranes into buds and tubules of defined geometry and lipid composition. However, these proteins exhibit an unexplained wide diversity of membrane-deforming activities in vitro and functions in vivo. We find that the F-BAR domain of the neuronal protein Nervous Wreck (Nwk) has a novel higher-order structure and membrane-deforming activity that distinguishes it from previously described F-BAR proteins. The Nwk F-BAR domain assembles into zigzags, creating ridges and periodic scallops on membranes in vitro. This activity depends on structural determinants at the tips of the F-BAR dimer and on electrostatic interactions of the membrane with the F-BAR concave surface. In cells, Nwk-induced scallops can be extended by cytoskeletal forces to produce protrusions at the plasma membrane. Our results define a new F-BAR membrane-deforming activity and illustrate a molecular mechanism by which positively curved F-BAR domains can produce a variety of membrane curvatures. These findings expand the repertoire of F-BAR domain mediated membrane deformation and suggest that unique modes of higher-order assembly can define how these proteins sculpt the membrane. DOI PubMed
4.Becalska, AN; Kim, YR; Belletier, NG; Lerit, DA; Sinsimer, KS; Gavis, ER. (2011) Aubergine is a component of a nanos mRNA localization complex.Dev. Biol. 349: 46-52 Aubergine is a component of a nanos mRNA localization complex
Aubergine; nanos; Drosophila; mRNA localization; Rumplestiltskin; Segmentation
Localization of nanos (nos) mRNA to the posterior pole of the Drosophila oocyte is essential for abdominal segmentation and germline development during embryogenesis. Posterior localization is mediated by a complex cis-acting localization signal in the nos 3' untranslated region that comprises multiple partially redundant elements. Genetic analysis suggests that this signal is recognized by RNA-binding proteins and associated factors that package nos mRNA into a localization competent ribonucleoprotein complex. However, functional redundancy among localization elements has made the identification of individual localization factors difficult. Indeed, only a single direct-acting nos localization factor, Rumpelstiltskin (Rump), has been identified thus far. Through a sensitized genetic screen, we have now identified the Argonaute family member Aubergine (Aub) as a nos localization factor. Aub interacts with nos mRNA in vivo and co-purifies with Rump in an RNA-dependent manner. Our results support a role for Aub, independent of its function in RNA silencing, as a component of a nos mRNA localization complex. (C) 2010 Elsevier Inc. All rights reserved. DOI PubMed
2.Becalska, AN; Gavis, ER. (2010) Bazooka regulates microtubule organization and spatial restriction of germ plasm assembly in the Drosophila oocyte.Dev. Biol. 340: 528-538 Bazooka regulates microtubule organization and spatial restriction of germ plasm assembly in the Drosophila oocyte
Bazooka/Par-3; Drosophila oogenesis; Axis formation; Germ plasm
Localization of the germ plasm to the posterior of the Drosophila oocyte is required for anteroposterior patterning and germ cell development during embryogenesis. While mechanisms governing the localization of individual germ plasm components have been elucidated, the process by which germ plasm assembly is restricted to the posterior pole is poorly understood. In this study, we identify a novel allele of bazooka (baz), the Drosophila homolog of Par-3, which has allowed the analysis of baz function throughout oogenesis. We demonstrate that baz is required for spatial restriction of the germ plasm and axis patterning, and we uncover multiple requirements for baz in regulating the organization of the oocyte microtubule cytoskeleton. Our results suggest that distinct cortical domains established by Par proteins polarize the oocyte through differential effects on microtubule organization. We further show that microtubule plus-end enrichment is sufficient to drive germ plasm assembly even at a distance from the oocyte cortex, suggesting that control of microtubule organization is critical not only for the localization of germ plasm components to the posterior of the oocyte but also for the restriction of germ plasm assembly to the posterior pole. (C) 2010 Elsevier Inc. All rights reserved. DOI PubMed
1.Becalska, AN; Gavis, ER. (2009) Lighting up mRNA localization in Drosophila oogenesis.Development 136: 2493-2503 Lighting up mRNA localization in Drosophila oogenesis
The asymmetric localization of four maternal mRNAs - gurken, bicoid, oskar and nanos - in the Drosophila oocyte is essential for the development of the embryonic body axes. Fluorescent imaging methods are now being used to visualize these mRNAs in living tissue, allowing dynamic analysis of their behaviors throughout the process of localization. This review summarizes recent findings from such studies that provide new insight into the elaborate cellular mechanisms that are used to transport mRNAs to different regions of the oocyte and to maintain their localized distributions during oogenesis. DOI PubMed
