scholarly journals Megator, an Essential Coiled-Coil Protein that Localizes to the Putative Spindle Matrix during Mitosis inDrosophila

2004 ◽  
Vol 15 (11) ◽  
pp. 4854-4865 ◽  
Author(s):  
Hongying Qi ◽  
Uttama Rath ◽  
Dong Wang ◽  
Ying-Zhi Xu ◽  
Yun Ding ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Matrix Proteins ◽  
P Element ◽  
Structural Basis ◽  
Spindle Matrix ◽  
Terminal Domain ◽  
Coiled Coil Domain ◽  
Coiled Coil Region ◽  
Spherical Structures ◽  
Spindle Structure

We have used immunocytochemistry and cross-immunoprecipitation analysis to demonstrate that Megator (Bx34 antigen), a Tpr ortholog in Drosophila with an extended coiled-coil domain, colocalizes with the putative spindle matrix proteins Skeletor and Chromator during mitosis. Analysis of P-element mutations in the Megator locus showed that Megator is an essential protein. During interphase Megator is localized to the nuclear rim and occupies the intranuclear space surrounding the chromosomes. However, during mitosis Megator reorganizes and aligns together with Skeletor and Chromator into a fusiform spindle structure. The Megator metaphase spindle persists in the absence of microtubule spindles, strongly implying that the existence of the Megator-defined spindle does not require polymerized microtubules. Deletion construct analysis in S2 cells indicates that the COOH-terminal part of Megator without the coiled-coil region was sufficient for both nuclear as well as spindle localization. In contrast, the NH2-terminal coiled-coil region remains in the cytoplasm; however, we show that it is capable of assembling into spherical structures. On the basis of these findings we propose that the COOH-terminal domain of Megator functions as a targeting and localization domain, whereas the NH2-terminal domain is responsible for forming polymers that may serve as a structural basis for the putative spindle matrix complex.

scholarly journals Model for the architecture of caveolae based on a flexible, net-like assembly of Cavin1 and Caveolin discs

2016 ◽  
Vol 113 (50) ◽  
pp. E8069-E8078 ◽  
Author(s):  
Miriam Stoeber ◽  
Pascale Schellenberger ◽  
C. Alistair Siebert ◽  
Cedric Leyrat ◽  
Ari Helenius ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Complex Formation ◽  
Membrane Binding ◽  
Coiled Coil ◽  
Structural Basis ◽  
Membrane Domains ◽  
Coiled Coil Domain ◽  
Regular Dodecahedron ◽  
Plasma Membrane Domains ◽  
Electron Cryotomography

Caveolae are invaginated plasma membrane domains involved in mechanosensing, signaling, endocytosis, and membrane homeostasis. Oligomers of membrane-embedded caveolins and peripherally attached cavins form the caveolar coat whose structure has remained elusive. Here, purified Cavin1 60S complexes were analyzed structurally in solution and after liposome reconstitution by electron cryotomography. Cavin1 adopted a flexible, net-like protein mesh able to form polyhedral lattices on phosphatidylserine-containing vesicles. Mutating the two coiled-coil domains in Cavin1 revealed that they mediate distinct assembly steps during 60S complex formation. The organization of the cavin coat corresponded to a polyhedral nano-net held together by coiled-coil segments. Positive residues around the C-terminal coiled-coil domain were required for membrane binding. Purified caveolin 8S oligomers assumed disc-shaped arrangements of sizes that are consistent with the discs occupying the faces in the caveolar polyhedra. Polygonal caveolar membrane profiles were revealed in tomograms of native caveolae inside cells. We propose a model with a regular dodecahedron as structural basis for the caveolae architecture.

scholarly journals Expression, purification and preliminary structural analysis of the coiled-coil domain ofDeinococcus radioduransRecN

2012 ◽  
Vol 68 (2) ◽  
pp. 218-221 ◽  
Author(s):  
Simone Pellegrino ◽  
Daniele de Sanctis ◽  
Sean McSweeney ◽  
Joanna Timmins
Keyword(s):  
Model Building ◽  
Deinococcus Radiodurans ◽  
Coiled Coil ◽  
Globular Domain ◽  
Entire Genome ◽  
Saxs Data ◽  
Coiled Coil Domain ◽  
Density Maps ◽  
Coiled Coil Region ◽  
High Doses

Deinococcus radioduranshas developed an efficient mechanism which allows the integrity of its entire genome to be fully restored after exposure to very high doses of ionizing radiation. Homologous recombination plays a crucial role in this process. RecN is a protein that belongs to the SMC-like protein family and is suggested to be involved in DNA repair. RecN is composed of a globular domain and an antiparallel coiled-coil region which connects the N- and C-termini. It has been suggested that dimerization of RecN occursviathe coiled-coil domain, but to date there is no structural or biochemical evidence for this. Here, SAXS studies and preliminary X-ray diffraction data of crystals of the purified coiled-coil domain of RecN are presented. The structure was solved by single-wavelength anomalous dispersion using SeMet derivatives, and preliminary electron-density maps support the rod-like model derived from the SAXS data. Model building and refinement are still ongoing.

scholarly journals Structural basis of NLR activation and innate immune signalling in plants

2022 ◽  
Author(s):  
Natsumi Maruta ◽  
Hayden Burdett ◽  
Bryan Y. J. Lim ◽  
Xiahao Hu ◽  
Sneha Desa ◽  
...  
Keyword(s):  
Immune Responses ◽  
Interleukin 1 ◽  
Three Dimensional ◽  
Coiled Coil ◽  
Innate Immune ◽  
Structural Basis ◽  
Innate Immune Responses ◽  
Oligomeric State ◽  
Coiled Coil Domain ◽  
The Family

AbstractAnimals and plants have NLRs (nucleotide-binding leucine-rich repeat receptors) that recognize the presence of pathogens and initiate innate immune responses. In plants, there are three types of NLRs distinguished by their N-terminal domain: the CC (coiled-coil) domain NLRs, the TIR (Toll/interleukin-1 receptor) domain NLRs and the RPW8 (resistance to powdery mildew 8)-like coiled-coil domain NLRs. CC-NLRs (CNLs) and TIR-NLRs (TNLs) generally act as sensors of effectors secreted by pathogens, while RPW8-NLRs (RNLs) signal downstream of many sensor NLRs and are called helper NLRs. Recent studies have revealed three dimensional structures of a CNL (ZAR1) including its inactive, intermediate and active oligomeric state, as well as TNLs (RPP1 and ROQ1) in their active oligomeric states. Furthermore, accumulating evidence suggests that members of the family of lipase-like EDS1 (enhanced disease susceptibility 1) proteins, which are uniquely found in seed plants, play a key role in providing a link between sensor NLRs and helper NLRs during innate immune responses. Here, we summarize the implications of the plant NLR structures that provide insights into distinct mechanisms of action by the different sensor NLRs and discuss plant NLR-mediated innate immune signalling pathways involving the EDS1 family proteins and RNLs.

scholarly journals The homo-oligomerisation of both Sas-6 and Ana2 is required for efficient centriole assembly in flies

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Matthew A Cottee ◽  
Nadine Muschalik ◽  
Steven Johnson ◽  
Joanna Leveson ◽  
Jordan W Raff ◽  
...  
Keyword(s):  
Point Mutations ◽  
Coiled Coil ◽  
Higher Order ◽  
Centriole Duplication ◽  
Terminal Domain ◽  
Coiled Coil Domain ◽  
Centriole Assembly ◽  
Tetramer Structure

Sas-6 and Ana2/STIL proteins are required for centriole duplication and the homo-oligomerisation properties of Sas-6 help establish the ninefold symmetry of the central cartwheel that initiates centriole assembly. Ana2/STIL proteins are poorly conserved, but they all contain a predicted Central Coiled-Coil Domain (CCCD). Here we show that the Drosophila Ana2 CCCD forms a tetramer, and we solve its structure to 0.8 Å, revealing that it adopts an unusual parallel-coil topology. We also solve the structure of the Drosophila Sas-6 N-terminal domain to 2.9 Å revealing that it forms higher-order oligomers through canonical interactions. Point mutations that perturb Sas-6 or Ana2 homo-oligomerisation in vitro strongly perturb centriole assembly in vivo. Thus, efficient centriole duplication in flies requires the homo-oligomerisation of both Sas-6 and Ana2, and the Ana2 CCCD tetramer structure provides important information on how these proteins might cooperate to form a cartwheel structure.

scholarly journals Relevance of Ebola virus VP35 homo-dimerization on the type I interferon cascade inhibition

2019 ◽  
Vol 27 ◽  
pp. 204020661988922 ◽  
Author(s):  
Francesco Di Palma ◽  
Gian Luca Daino ◽  
Venkata Krishnan Ramaswamy ◽  
Angela Corona ◽  
Aldo Frau ◽  
...  
Keyword(s):  
Ebola Virus ◽  
Type I Interferon ◽  
Coiled Coil ◽  
Coarse Grained ◽  
Type I ◽  
Wild Type ◽  
Terminal Domain ◽  
Coiled Coil Region ◽  
Interferon Antagonism

Ebola virus high lethality relies on its ability to efficiently bypass the host innate antiviral response, which senses the viral dsRNA through the RIG-I receptor and induces type I interferon α/β production. In the bypassing action, the Ebola virus protein VP35 plays a pivotal role at multiple levels of the RIG-I cascade, masking the viral 5′-triphosphorylated dsRNA from RIG-I, and interacting with other cascade components. The VP35 type I interferon inhibition is exerted by the C-terminal domain, while the N-terminal domain, containing a coiled-coil region, is primarily required for oligomerization. However, mutations at key VP35 residues L90/93/107A (VP35-3m) in the coiled-coil region were reported to affect oligomerization and reduce type I interferon antagonism, indicating a possible but unclear role of homo-oligomerization on VP35 interaction with the RIG-I pathway components. In this work, we investigated the VP35 dimerization thermodynamics and its contribution to type I interferon antagonism by computational and biological methods. Focusing on the coiled-coil region, we combined coarse-grained and all-atom simulations on wild type VP35 and VP35-3m homo-dimerization. According to our results, wild type VP35 coiled-coil is able to self-assemble into dimers, while VP35-3m coiled-coil shows poor propensity to even dimerize. Free-energy calculations confirmed the key role of L90, L93 and L107 in stabilizing the coiled-coil homo-dimeric structure. In vitro type I interferon antagonism studies, using full-length wild type VP35 and VP35-3m, revealed that VP35 homo-dimerization is an essential preliminary step for dsRNA binding, which appears to be the main factor of the VP35 RIG-I cascade inhibition, while it is not essential to block the other steps.

scholarly journals Accommodation of structural rearrangements in the huntingtin-interacting protein 1 coiled-coil domain

2010 ◽  
Vol 66 (3) ◽  
pp. 314-318 ◽  
Author(s):  
Jeremy D. Wilbur ◽  
Peter K. Hwang ◽  
Frances M. Brodsky ◽  
Robert J. Fletterick
Keyword(s):  
Light Chain ◽  
Coiled Coil ◽  
Actin Binding ◽  
Interacting Protein ◽  
Similar Region ◽  
Coiled Coil Domain ◽  
Coiled Coil Region ◽  
Huntingtin Interacting Protein 1 ◽  
Conformational Regulation ◽  
Huntingtin Interacting Protein

Huntingtin-interacting protein 1 (HIP1) is an important link between the actin cytoskeleton and clathrin-mediated endocytosis machinery. HIP1 has also been implicated in the pathogenesis of Huntington's disease. The binding of HIP1 to actin is regulated through an interaction with clathrin light chain. Clathrin light chain binds to a flexible coiled-coil domain in HIP1 and induces a compact state that is refractory to actin binding. To understand the mechanism of this conformational regulation, a high-resolution crystal structure of a stable fragment from the HIP1 coiled-coil domain was determined. The flexibility of the HIP1 coiled-coil region was evident from its variation from a previously determined structure of a similar region. A hydrogen-bond network and changes in coiled-coil monomer interaction suggest that the HIP1 coiled-coil domain is uniquely suited to allow conformational flexibility.

scholarly journals The crystal structure of mouse LC3B in complex with the FYCO1 LIR reveals the importance of the flanking region of the LIR motif

2017 ◽  
Vol 73 (3) ◽  
pp. 130-137 ◽  
Author(s):  
Shunya Sakurai ◽  
Taisuke Tomita ◽  
Toshiyuki Shimizu ◽  
Umeharu Ohto
Keyword(s):  
Crystal Structure ◽  
Coiled Coil ◽  
Adaptor Protein ◽  
Structural Basis ◽  
Core Sequence ◽  
Coiled Coil Domain ◽  
Flanking Sequences ◽  
Flanking Region ◽  
Membrane Components ◽  
Lir Motif

FYVE and coiled-coil domain-containing protein 1 (FYCO1), a multidomain autophagy adaptor protein, mediates microtubule plus-end-directed autophagosome transport by interacting with kinesin motor proteins and with the autophagosomal membrane components microtubule-associated protein 1 light chain 3 (LC3), Rab7 and phosphatidylinositol 3-phosphate (PI3P). To establish the structural basis for the recognition of FYCO1 by LC3, the crystal structure of mouse LC3B in complex with the FYCO1 LC3-interacting region (LIR) motif peptide was determined. Structural analysis showed that the flanking sequences N-terminal and C-terminal to the LIR core sequence of FYCO1, as well as the tetrapeptide core sequence, were specifically recognized by LC3B and contributed to the binding. Moreover, comparisons of related structures revealed a conserved mechanism of FYCO1 recognition by different LC3 isoforms among different species.

scholarly journals N-terminus-mediated dimerization of ROCK-I is required for RhoE binding and actin reorganization

2008 ◽  
Vol 411 (2) ◽  
pp. 407-414 ◽  
Author(s):  
Ritu Garg ◽  
Kirsi Riento ◽  
Nicholas Keep ◽  
Jonathan D. H. Morris ◽  
Anne J. Ridley
Keyword(s):  
Kinase Activity ◽  
Coiled Coil ◽  
Kinase Domain ◽  
Serine Threonine Kinase ◽  
Actin Reorganization ◽  
Coiled Coil Domain ◽  
C Terminus ◽  
Coiled Coil Region ◽  
N Terminus ◽  
In Cells

ROCK-I (Rho-associated kinase 1) is a serine/threonine kinase that can be activated by RhoA and inhibited by RhoE. ROCK-I has an N-terminal kinase domain, a central coiled-coil region and a RhoA-binding domain near the C-terminus. We have previously shown that RhoE binds to the N-terminal 420 amino acids of ROCK-I, which includes the kinase domain as well as N-terminal and C-terminal extensions. In the present study, we show that N-terminus-mediated dimerization of ROCK-I is required for RhoE binding. The central coiled-coil domain can also dimerize ROCK-I in cells, but this is insufficient in the absence of the N-terminus to allow RhoE binding. The kinase activity of ROCK-I1–420 is required for dimerization and RhoE binding; however, inclusion of part of the coiled-coil domain compensates for lack of kinase activity, allowing RhoE to bind. N-terminus-mediated dimerization is also required for ROCK-I to induce the formation of stellate actin stress fibres in cells. These results indicate that dimerization via the N-terminus is critical for ROCK-I function in cells and for its regulation by RhoE.

scholarly journals Structural Basis of Mitochondrial Scaffolds by Prohibitin Complexes: Insight into a Role of the Coiled-Coil Region

iScience ◽  
2019 ◽  
Vol 19 ◽  
pp. 1065-1078 ◽  
Author(s):  
Takahiro Yoshinaka ◽  
Hidetaka Kosako ◽  
Takuma Yoshizumi ◽  
Ryo Furukawa ◽  
Yu Hirano ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Structural Basis ◽  
Coiled Coil Region ◽  
Insight Into

scholarly journals Stu2 uses a 15-nm parallel coiled coil for kinetochore localization and concomitant regulation of the mitotic spindle

2018 ◽  
Vol 29 (3) ◽  
pp. 285-294 ◽  
Author(s):  
Karen P. Haase ◽  
Jaime C. Fox ◽  
Amy E. Byrnes ◽  
Rebecca C. Adikes ◽  
Sarah K. Speed ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Coiled Coil ◽  
Structure And Dynamics ◽  
Conserved Regions ◽  
Terminal Domain ◽  
Spindle Structure

The yeast microtubule polymerase Stu2’s C-terminal domain is a 15-nm parallel, homodimeric coiled coil with two spatially distinct conserved regions. Determinants in these conserved regions optimally position Stu2 on the mitotic spindle to drive proper spindle structure and dynamics.

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