scholarly journals Structural biology of laminins

2019 ◽  
Vol 63 (3) ◽  
pp. 285-295 ◽  
Author(s):  
Erhard Hohenester
Keyword(s):  
Structural Biology ◽  
Coiled Coil ◽  
Large Cell ◽  
Basement Membranes ◽  
Cell Adhesive ◽  
A Cell ◽  
The Cross ◽  
And Function ◽  
Polypeptide Chains

Abstract Laminins are large cell-adhesive glycoproteins that are required for the formation and function of basement membranes in all animals. Structural studies by electron microscopy in the early 1980s revealed a cross-shaped molecule, which subsequently was shown to consist of three distinct polypeptide chains. Crystallographic studies since the mid-1990s have added atomic detail to all parts of the laminin heterotrimer. The three short arms of the cross are made up of continuous arrays of disulphide-rich domains. The globular domains at the tips of the short arms mediate laminin polymerization; the surface regions involved in this process have been identified by structure-based mutagenesis. The long arm of the cross is an α-helical coiled coil of all three chains, terminating in a cell-adhesive globular region. The molecular basis of cell adhesion to laminins has been revealed by recent structures of heterotrimeric integrin-binding fragments and of a laminin fragment bound to the carbohydrate modification of dystroglycan. The structural characterization of the laminin molecule is essentially complete, but we still have to find ways of imaging native laminin polymers at molecular resolution.

scholarly journals Roles of the novel coiled-coil protein Rng10 in septum formation during fission yeast cytokinesis

2016 ◽  
Vol 27 (16) ◽  
pp. 2528-2541 ◽  
Author(s):  
Yajun Liu ◽  
I-Ju Lee ◽  
Mingzhai Sun ◽  
Casey A. Lower ◽  
Kurt W. Runge ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Rho Gtpases ◽  
Cellular Localization ◽  
Affinity Purification ◽  
Coiled Coil ◽  
The Novel ◽  
Septum Formation ◽  
Division Site ◽  
And Function

Rho GAPs are important regulators of Rho GTPases, which are involved in various steps of cytokinesis and other processes. However, regulation of Rho-GAP cellular localization and function is not fully understood. Here we report the characterization of a novel coiled-coil protein Rng10 and its relationship with the Rho-GAP Rga7 in fission yeast. Both rng10Δ and rga7Δ result in defective septum and cell lysis during cytokinesis. Rng10 and Rga7 colocalize on the plasma membrane at the cell tips during interphase and at the division site during cell division. Rng10 physically interacts with Rga7 in affinity purification and coimmunoprecipitation. Of interest, Rga7 localization is nearly abolished without Rng10. Moreover, Rng10 and Rga7 work together to regulate the accumulation and dynamics of glucan synthases for successful septum formation in cytokinesis. Our results show that cellular localization and function of the Rho-GAP Rga7 are regulated by a novel protein, Rng10, during cytokinesis in fission yeast.

scholarly journals High-resolution structures of a heterochiral coiled coil

2015 ◽  
Vol 112 (43) ◽  
pp. 13144-13149 ◽  
Author(s):  
David E. Mortenson ◽  
Jay D. Steinkruger ◽  
Dale F. Kreitler ◽  
Dominic V. Perroni ◽  
Gregory P. Sorenson ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Structural Information ◽  
Coiled Coil ◽  
Coiled Coils ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Polypeptide Chains ◽  
Packing Interactions

Interactions between polypeptide chains containing amino acid residues with opposite absolute configurations have long been a source of interest and speculation, but there is very little structural information for such heterochiral associations. The need to address this lacuna has grown in recent years because of increasing interest in the use of peptides generated from d amino acids (d peptides) as specific ligands for natural proteins, e.g., to inhibit deleterious protein–protein interactions. Coiled–coil interactions, between or among α-helices, represent the most common tertiary and quaternary packing motif in proteins. Heterochiral coiled–coil interactions were predicted over 50 years ago by Crick, and limited experimental data obtained in solution suggest that such interactions can indeed occur. To address the dearth of atomic-level structural characterization of heterochiral helix pairings, we report two independent crystal structures that elucidate coiled-coil packing between l- and d-peptide helices. Both structures resulted from racemic crystallization of a peptide corresponding to the transmembrane segment of the influenza M2 protein. Networks of canonical knobs-into-holes side-chain packing interactions are observed at each helical interface. However, the underlying patterns for these heterochiral coiled coils seem to deviate from the heptad sequence repeat that is characteristic of most homochiral analogs, with an apparent preference for a hendecad repeat pattern.

Domain organizations of extracellular matrix proteins and their evolution

Development ◽  
1994 ◽  
Vol 1994 (Supplement) ◽  
pp. 35-42
Author(s):  
Jürgen Engel ◽  
Vladimir P. Efimov ◽  
Patrik Maurer
Keyword(s):  
Extracellular Matrix ◽  
Cell Signalling ◽  
Coiled Coil ◽  
Structure And Function ◽  
Matrix Proteins ◽  
Cell Binding ◽  
Ecm Proteins ◽  
Triple Helices ◽  
And Function ◽  
Polypeptide Chains

The astonishing diversity in structure and function of extracellular matrix (ECM) proteins originates from different combinations of domains. These are defined as autonomously folding units. Many domains are similar in sequence and structure indicating common ancestry. Evolutionarily homologous domains are, however, often functionally very different, which renders function prediction from sequence difficult. Related and different domains are frequently repeated in the same or in different polypeptide chains. Common assembly domains include α-helical coiled-coil domains and collagen triple helices. Other domains have been shown to be involved in assembly to other ECM proteins or in cell binding and cell signalling. The function of most of the domains, however, remains to be elucidated. ECM proteins are rather recent `inventions', and most occur either in plants or mammals but not in both. Their creation by domain shuffling involved a number of different mechanisms at the DNA level in which introns played an important role.

scholarly journals Segregation and activation of myosin IIB creates a rear in migrating cells

2008 ◽  
Vol 183 (3) ◽  
pp. 543-554 ◽  
Author(s):  
Miguel Vicente-Manzanares ◽  
Margaret A. Koach ◽  
Leanna Whitmore ◽  
Marcelo L. Lamers ◽  
Alan F. Horwitz
Keyword(s):  
Self Assembly ◽  
De Novo ◽  
Coiled Coil ◽  
Myosin Isoforms ◽  
C Terminus ◽  
Filament Bundles ◽  
A Cell ◽  
Myosin Iia ◽  
And Function ◽  
Migrating Cells

We have found that MLC-dependent activation of myosin IIB in migrating cells is required to form an extended rear, which coincides with increased directional migration. Activated myosin IIB localizes prominently at the cell rear and produces large, stable actin filament bundles and adhesions, which locally inhibit protrusion and define the morphology of the tail. Myosin IIA forms de novo filaments away from the myosin IIB–enriched center and back to form regions that support protrusion. The positioning and dynamics of myosin IIA and IIB depend on the self-assembly regions in their coiled-coil C terminus. COS7 and B16 melanoma cells lack myosin IIA and IIB, respectively; and show isoform-specific front-back polarity in migrating cells. These studies demonstrate the role of MLC activation and myosin isoforms in creating a cell rear, the segregation of isoforms during filament assembly and their differential effects on adhesion and protrusion, and a key role for the noncontractile region of the isoforms in determining their localization and function.

Ruthenium phthalocyanines with axial carboxylate ligands: Synthesis and function in solar cells based on nanocrystalline TiO2

2002 ◽  
Vol 06 (03) ◽  
pp. 217-224 ◽  
Author(s):  
Masaru Yanagisawa ◽  
Ferenc Korodi ◽  
Jianjun He ◽  
Licheng Sun ◽  
Villy Sundström ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Nanocrystalline Tio2 ◽  
Axial Ligands ◽  
Phthalocyanine Dyes ◽  
A Cell ◽  
Flash Column Chromatography ◽  
And Function

The synthesis and characterization of phthalocyaninato-ruthenium ( PcRu ) complexes with potential functional axial ligands are described. The solubility of these PcRu complexes was much improved compared to their parent phthalocyanines without Ru , enabling purification by normal flash column chromatography and also NMR measurements in common solvents (e. g. DMSO - d 6 and CDCl 3). Adsorption of these phthalocyanine dyes onto the surface of a semiconductor through the carboxyl group(s) in the axial ligands prevents to some extent formation of H-aggregates, which is typical for phthalocyanines. It also prevents stacking of the dye molecules on the surface. The photovoltaic behavior of sandwich solar cells based on nanostructured TiO 2 films sensitized by these PcRu complexes was studied under irradiation with visible light. For a solar cell based on bis(4-carboxypyridine)-phthalocyaninato ruthenium(II) (1) sensitized nanoporous-nanocrystalline TiO 2, a monochromatic incident photon-to-current conversion efficiency (IPCE) of 21% was obtained at 640 nm. The overall conversion efficiency (η) was 0.61%, which is one of the best results for a solar cell based on a phthalocyanine dye. For a cell based on (4-carboxypyridine)-(4-(2-ethoxy)ethyloxycarbo-nylpyridine)-2,3,9,10,16,17,23,24-octa(n-pentyloxy)-phthalocyaninato ruthenium(II) (5) sensitized TiO 2, a IPCE of 6.6% at 640 nm and η of 0.58% were obtained.

scholarly journals RHAMM Is a Centrosomal Protein That Interacts with Dynein and Maintains Spindle Pole Stability

2003 ◽  
Vol 14 (6) ◽  
pp. 2262-2276 ◽  
Author(s):  
Christopher A. Maxwell ◽  
Jonathan J. Keats ◽  
Mary Crainie ◽  
Xuejun Sun ◽  
Tim Yen ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Direct Interaction ◽  
Spindle Pole ◽  
Cell Surface Receptor ◽  
Interaction Domain ◽  
Surface Receptor ◽  
A Cell ◽  
Carboxy Terminal ◽  
And Function ◽  
Hyaluronan Binding

The receptor for hyaluronan-mediated motility (RHAMM), an acidic coiled coil protein, has previously been characterized as a cell surface receptor for hyaluronan, and a microtubule-associated intracellular hyaluronan binding protein. In this study, we demonstrate that a subset of cellular RHAMM localizes to the centrosome and functions in the maintenance of spindle integrity. We confirm a previous study showing that the amino terminus of RHAMM interacts with microtubules and further demonstrate that a separate carboxy-terminal domain is required for centrosomal targeting. This motif overlaps the defined hyaluronan binding domain and bears 72% identity to the dynein interaction domain of Xklp2. RHAMM antibodies coimmunprecipitate dynein IC from Xenopus and HeLa extracts. Deregulation of RHAMM expression inhibits mitotic progression and affects spindle architecture. Structure, localization, and function, along with phylogenetic analysis, suggests that RHAMM may be a new member of the TACC family. Thus, we demonstrate a novel centrosomal localization and mitotic spindle-stabilizing function for RHAMM. Moreover, we provide a potential mechanism for this function in that RHAMM may cross-link centrosomal microtubules, through a direct interaction with microtubules and an association with dynein.

scholarly journals A yeast-optimized single-cell transcriptomics platform elucidates how mycophenolic acid and guanine alter global mRNA levels

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Guste Urbonaite ◽  
Jimmy Tsz Hang Lee ◽  
Ping Liu ◽  
Guillermo E. Parada ◽  
Martin Hemberg ◽  
...  
Keyword(s):  
Single Cell ◽  
Mycophenolic Acid ◽  
Mammalian Cells ◽  
Yeast Cells ◽  
Mrna Levels ◽  
A Cell ◽  
Size And Morphology ◽  
And Function ◽  
Morphology Characteristics

AbstractStochastic gene expression leads to inherent variability in expression outcomes even in isogenic single-celled organisms grown in the same environment. The Drop-Seq technology facilitates transcriptomic studies of individual mammalian cells, and it has had transformative effects on the characterization of cell identity and function based on single-cell transcript counts. However, application of this technology to organisms with different cell size and morphology characteristics has been challenging. Here we present yeastDrop-Seq, a yeast-optimized platform for quantifying the number of distinct mRNA molecules in a cell-specific manner in individual yeast cells. Using yeastDrop-Seq, we measured the transcriptomic impact of the lifespan-extending compound mycophenolic acid and its epistatic agent guanine. Each treatment condition had a distinct transcriptomic footprint on isogenic yeast cells as indicated by distinct clustering with clear separations among the different groups. The yeastDrop-Seq platform facilitates transcriptomic profiling of yeast cells for basic science and biotechnology applications.

Functional characterization of human brown adipose tissue metabolism

2020 ◽  
Vol 477 (7) ◽  
pp. 1261-1286 ◽  
Author(s):  
Marie Anne Richard ◽  
Hannah Pallubinsky ◽  
Denis P. Blondin
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Functional Characterization ◽  
Human Infants ◽  
Positron Emission ◽  
Brown Adipose ◽  
Treatment Of Obesity ◽  
And Function

Brown adipose tissue (BAT) has long been described according to its histological features as a multilocular, lipid-containing tissue, light brown in color, that is also responsive to the cold and found especially in hibernating mammals and human infants. Its presence in both hibernators and human infants, combined with its function as a heat-generating organ, raised many questions about its role in humans. Early characterizations of the tissue in humans focused on its progressive atrophy with age and its apparent importance for cold-exposed workers. However, the use of positron emission tomography (PET) with the glucose tracer [18F]fluorodeoxyglucose ([18F]FDG) made it possible to begin characterizing the possible function of BAT in adult humans, and whether it could play a role in the prevention or treatment of obesity and type 2 diabetes (T2D). This review focuses on the in vivo functional characterization of human BAT, the methodological approaches applied to examine these features and addresses critical gaps that remain in moving the field forward. Specifically, we describe the anatomical and biomolecular features of human BAT, the modalities and applications of non-invasive tools such as PET and magnetic resonance imaging coupled with spectroscopy (MRI/MRS) to study BAT morphology and function in vivo, and finally describe the functional characteristics of human BAT that have only been possible through the development and application of such tools.

Parasite defense mechanisms in bees: behavior, immunity, antimicrobials, and symbionts

2019 ◽  
Vol 4 (1) ◽  
pp. 59-76 ◽  
Author(s):  
Alison E. Fowler ◽  
Rebecca E. Irwin ◽  
Lynn S. Adler
Keyword(s):  
Defense Mechanisms ◽  
Poor Quality ◽  
Future Research ◽  
Immune Priming ◽  
Social Bees ◽  
Bee Health ◽  
Landscape Scales ◽  
And Function ◽  
Solitary Species

Parasites are linked to the decline of some bee populations; thus, understanding defense mechanisms has important implications for bee health. Recent advances have improved our understanding of factors mediating bee health ranging from molecular to landscape scales, but often as disparate literatures. Here, we bring together these fields and summarize our current understanding of bee defense mechanisms including immunity, immunization, and transgenerational immune priming in social and solitary species. Additionally, the characterization of microbial diversity and function in some bee taxa has shed light on the importance of microbes for bee health, but we lack information that links microbial communities to parasite infection in most bee species. Studies are beginning to identify how bee defense mechanisms are affected by stressors such as poor-quality diets and pesticides, but further research on this topic is needed. We discuss how integrating research on host traits, microbial partners, and nutrition, as well as improving our knowledge base on wild and semi-social bees, will help inform future research, conservation efforts, and management.

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