scholarly journals Molecular Architecture of the Bardet-Biedl Syndrome Protein 2-7-9 Subcomplex

2019 ◽  
Author(s):  
W. Grant Ludlam ◽  
Takuma Aoba ◽  
Jorge Cuéllar ◽  
M. Teresa Bueno-Carrasco ◽  
Aman Makaju ◽  
...  
Keyword(s):  
Genetic Disease ◽  
Molecular Basis ◽  
Primary Cilia ◽  
Molecular Model ◽  
Coiled Coil ◽  
Chemical Crosslinking ◽  
Molecular Architecture ◽  
Bardet Biedl Syndrome ◽  
Helical Domain ◽  
Syndrome Protein

SummaryBardet-Biedl syndrome (BBS) is a genetic disease caused by mutations that disrupt the function of the BBSome, an eight-subunit complex that plays an important role in transport of proteins in primary cilia. To better understand the molecular basis of the disease, we analyzed the structure of a BBSome subcomplex consisting of three homologous BBS proteins (BBS2, BBS7, and BBS9) by an integrative structural modeling approach using electron microscopy and chemical crosslinking coupled with mass spectrometry. The resulting molecular model revealed an overall structure that resembles a flattened triangle. Within the structure, BBS2 and BBS7 form a tight dimer based on a coiled-coil interaction, and BBS9 associates with the dimer via an interaction with the α-helical domain of BBS2. Interestingly, a BBS-linked mutation of BBS2 (R632P) is located in the α-helical domain at the interface between BBS2 and BBS9, and binding experiments showed that this mutation disrupted the interaction of BBS2 with BBS9. This finding suggests that BBSome assembly is disrupted by the R632P substitution, providing a molecular explanation for BBS in patients harboring this mutation.

scholarly journals Addressing the Molecular Mechanism of Longitudinal Lamin Assembly Using Chimeric Fusions

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1633 ◽  
Author(s):  
Giel Stalmans ◽  
Anastasia V. Lilina ◽  
Pieter-Jan Vermeire ◽  
Jan Fiala ◽  
Petr Novák ◽  
...  
Keyword(s):  
Cell Nucleus ◽  
Molecular Model ◽  
Coiled Coil ◽  
Cross Linking ◽  
Specific Interactions ◽  
Molecular Architecture ◽  
Filament Assembly ◽  
Assembly Mechanism ◽  
Recombinant Fragments ◽  
Chemical Cross Linking

The molecular architecture and assembly mechanism of intermediate filaments have been enigmatic for decades. Among those, lamin filaments are of particular interest due to their universal role in cell nucleus and numerous disease-related mutations. Filament assembly is driven by specific interactions of the elementary dimers, which consist of the central coiled-coil rod domain flanked by non-helical head and tail domains. We aimed to investigate the longitudinal ‘head-to-tail’ interaction of lamin dimers (the so-called ACN interaction), which is crucial for filament assembly. To this end, we prepared a series of recombinant fragments of human lamin A centred around the N- and C-termini of the rod. The fragments were stabilized by fusions to heterologous capping motifs which provide for a correct formation of parallel, in-register coiled-coil dimers. As a result, we established crystal structures of two N-terminal fragments one of which highlights the propensity of the coiled-coil to open up, and one C-terminal rod fragment. Additional studies highlighted the capacity of such N- and C-terminal fragments to form specific complexes in solution, which were further characterized using chemical cross-linking. These data yielded a molecular model of the ACN complex which features a 6.5 nm overlap of the rod ends.

scholarly journals Molecular architecture of the Bardet–Biedl syndrome protein 2-7-9 subcomplex

2019 ◽  
Vol 294 (44) ◽  
pp. 16385-16399 ◽  
Author(s):  
W. Grant Ludlam ◽  
Takuma Aoba ◽  
Jorge Cuéllar ◽  
M. Teresa Bueno-Carrasco ◽  
Aman Makaju ◽  
...  
Keyword(s):  
Molecular Architecture ◽  
Bardet Biedl Syndrome ◽  
Syndrome Protein

scholarly journals Cryo-EM reveals the complex architecture of dynactin’s shoulder and pointed end

2020 ◽  
Author(s):  
Clinton K. Lau ◽  
Francis J. O’Reilly ◽  
Balaji Santhanam ◽  
Samuel E. Lacey ◽  
Juri Rappsilber ◽  
...  
Keyword(s):  
High Resolution ◽  
Molecular Basis ◽  
Molecular Motor ◽  
Coiled Coil ◽  
Molecular Architecture ◽  
Pointed End ◽  
Complex Architecture

AbstractDynactin is a 1.1 MDa complex that activates the molecular motor, dynein, for ultra-processive transport along microtubules. In order to do this it forms a tripartite complex with dynein and a coiled-coil adaptor. Dynactin consists of an actin-related filament whose length is defined by its flexible shoulder domain. Despite previous cryo-EM structures, the molecular architecture of the shoulder and pointed end of the filament is still poorly understood due to the lack of high-resolution information in these regions. Here we combine multiple cryo-EM datasets and define precise masking strategies for particle signal subtraction and 3D classification. This overcomes domain flexibility and results in high resolution maps into which we can build the shoulder and pointed end. The unique architecture of the shoulder positions the four identical p50 subunits in different conformations to bind dynactin’s filament and securely houses the p150 subunit. The pointed end map allows us to build the first structure of p62, and reveals the molecular basis for cargo adaptor binding to different sites at the pointed end.

scholarly journals Altered hematopoietic system and self-tolerance in Bardet-Biedl Syndrome

2020 ◽  
Author(s):  
Oksana Tsyklauri ◽  
Veronika Niederlova ◽  
Elizabeth Forsythe ◽  
Ales Drobek ◽  
Avishek Prasai ◽  
...  
Keyword(s):  
Immune System ◽  
Animal Models ◽  
Mouse Model ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Genetic Disease ◽  
Primary Cilia ◽  
Hematopoietic System ◽  
Bardet Biedl Syndrome ◽  
Self Tolerance

AbstractBardet-Biedl Syndrome (BBS) is a pleiotropic genetic disease caused by dysfunction of primary cilia. The immune system of patients with BBS or another ciliopathy has not been investigated, most likely because hematopoietic cells do not form cilia. However, there are multiple indications that the impairment of the processes typically associated with cilia might influence the hematopoietic compartment and immunity. In this study, we analyzed clinical data of BBS patients as well as a corresponding mouse model of BBS4 deficiency. We uncovered that BBS patients have higher incidence of certain autoimmune diseases. BBS patients and animal models have elevated white blood cell levels and altered red blood cell and platelet compartments. Moreover, we observed that BBS4 deficiency alters the development and homeostasis of B cells in mice. Some of the hematopoietic system alterations were caused by the BBS-induced obesity. Overall, our study reveals a connection between a ciliopathy and the alterations of the immune system and the hematopoietic compartment.

Exploration of cell wall architecture with the rapid-freeze deep-etch technique

1993 ◽  
Vol 51 ◽  
pp. 128-129
Author(s):  
Béatrice Satiat-Jeunemaitre ◽  
Chris Hawes
Keyword(s):  
Plant Cell ◽  
Cell Walls ◽  
Cell Biology ◽  
Molecular Model ◽  
Three Dimensional ◽  
Secretory Activity ◽  
Wall Structure ◽  
Specimen Preparation ◽  
Molecular Architecture ◽  
Plant Cell Walls

The comprehension of the molecular architecture of plant cell walls is one of the best examples in cell biology which illustrates how developments in microscopy have extended the frontiers of a topic. Indeed from the first electron microscope observation of cell walls it has become apparent that our understanding of wall structure has advanced hand in hand with improvements in the technology of specimen preparation for electron microscopy. Cell walls are sub-cellular compartments outside the peripheral plasma membrane, the construction of which depends on a complex cellular biosynthetic and secretory activity (1). They are composed of interwoven polymers, synthesised independently, which together perform a number of varied functions. Biochemical studies have provided us with much data on the varied molecular composition of plant cell walls. However, the detailed intermolecular relationships and the three dimensional arrangement of the polymers in situ remains a mystery. The difficulty in establishing a general molecular model for plant cell walls is also complicated by the vast diversity in wall composition among plant species.

scholarly journals Identification of a Coiled Coil in Werner Syndrome Protein That Facilitates Multimerization and Promotes Exonuclease Processivity

2010 ◽  
Vol 285 (33) ◽  
pp. 25699-25707 ◽  
Author(s):  
J. Jefferson P. Perry ◽  
Aroumougame Asaithamby ◽  
Adam Barnebey ◽  
Foad Kiamanesch ◽  
David J. Chen ◽  
...  
Keyword(s):  
Werner Syndrome ◽  
Coiled Coil ◽  
Werner Syndrome Protein ◽  
Syndrome Protein

scholarly journals cDNA Cloning of the Basement Membrane Chondroitin Sulfate Proteoglycan Core Protein, Bamacan: A Five Domain Structure Including Coiled-Coil Motifs

1997 ◽  
Vol 136 (2) ◽  
pp. 433-444 ◽  
Author(s):  
Rong-Rong Wu ◽  
John R. Couchman
Keyword(s):  
Basement Membrane ◽  
Chondroitin Sulfate ◽  
Core Protein ◽  
Coiled Coil ◽  
Basement Membranes ◽  
Cdna Clones ◽  
Molecular Architecture ◽  
Unusual Structure ◽  
Extracellular Matrix Molecule

Basement membranes contain several proteoglycans, and those bearing heparan sulfate glycosaminoglycans such as perlecan and agrin usually predominate. Most mammalian basement membranes also contain chondroitin sulfate, and a core protein, bamacan, has been partially characterized. We have now obtained cDNA clones encoding the entire bamacan core protein of Mr = 138 kD, which reveal a five domain, head-rod-tail configuration. The head and tail are potentially globular, while the central large rod probably forms coiled-coil structures, with one large central and several very short interruptions. This molecular architecture is novel for an extracellular matrix molecule, but it resembles that of a group of intracellular proteins, including some proposed to stabilize the mitotic chromosome scaffold. We have previously proposed a similar stabilizing role for bamacan in the basement membrane matrix. The protein sequence has low overall homology, apart from very small NH2- and COOH-terminal motifs. At the junctions between the distal globular domains and the coiled-coil regions lie glycosylation sites, with up to three N-linked oligosaccharides and probably three chondroitin chains. Three other Ser-Gly dipeptides are unfavorable for substitution. Fusion protein antibodies stained basement membranes in a pattern commensurate with bamacan, and they also Western blotted bamacan core protein from rat L2 cell cultures. The antibodies could also specifically immunoprecipitate an in vitro transcription/translation product from a full-length bamacan cDNA. The unusual structure of this proteoglycan is indicative of specific functional roles in basement membrane physiology, commensurate with its distinct expression in development and changes in disease models.

scholarly journals A conserved filamentous assembly underlies the structure of the meiotic chromosome axis

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Alan MV West ◽  
Scott C Rosenberg ◽  
Sarah N Ur ◽  
Madison K Lehmer ◽  
Qiaozhen Ye ◽  
...  
Keyword(s):  
Meiotic Recombination ◽  
Budding Yeast ◽  
Meiotic Chromosome ◽  
Coiled Coil ◽  
Chromosome Organization ◽  
Molecular Architecture ◽  
Master Regulators ◽  
Core Proteins ◽  
Protein Components ◽  
Chromosome Axis

The meiotic chromosome axis plays key roles in meiotic chromosome organization and recombination, yet the underlying protein components of this structure are highly diverged. Here, we show that ‘axis core proteins’ from budding yeast (Red1), mammals (SYCP2/SYCP3), and plants (ASY3/ASY4) are evolutionarily related and play equivalent roles in chromosome axis assembly. We first identify ‘closure motifs’ in each complex that recruit meiotic HORMADs, the master regulators of meiotic recombination. We next find that axis core proteins form homotetrameric (Red1) or heterotetrameric (SYCP2:SYCP3 and ASY3:ASY4) coiled-coil assemblies that further oligomerize into micron-length filaments. Thus, the meiotic chromosome axis core in fungi, mammals, and plants shares a common molecular architecture, and likely also plays conserved roles in meiotic chromosome axis assembly and recombination control.

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