scholarly journals A conserved mechanism for meiotic chromosome organization through self-assembly of a filamentous chromosome axis core

2018 ◽  
Author(s):  
Alan M.V. West ◽  
Scott C. Rosenberg ◽  
Sarah N. Ur ◽  
Madison K. Lehmer ◽  
Qiaozhen Ye ◽  
...  
Keyword(s):  
Self Assembly ◽  
Meiotic Chromosome ◽  
Coiled Coil ◽  
Chromosome Organization ◽  
Molecular Architecture ◽  
Master Regulators ◽  
Dna Loop ◽  
Core Proteins ◽  
Protein Components ◽  
Chromosome Axis

AbstractThe 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 motifs in each complex that recruit meiotic HORMADs, the master regulators of meiotic recombination. We next find that axis core complexes 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 role in axis assembly and recombination control. We propose that the meiotic chromosome axis self-assembles through cooperative interactions between dynamic DNA loop-extruding cohesin complexes and the filamentous axis core, then serves as a platform for chromosome organization, recombination, and synaptonemal complex assembly.

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.

scholarly journals Structural basis of meiotic chromosome synaptic elongation through hierarchical fibrous assembly of SYCE2-TEX12

2020 ◽  
Author(s):  
James M. Dunce ◽  
Lucy J. Salmon ◽  
Owen R. Davies
Keyword(s):  
Self Assembly ◽  
Meiotic Chromosome ◽  
Coiled Coil ◽  
Building Blocks ◽  
Chromosome Length ◽  
Structural Basis ◽  
Intermediate Filament Proteins ◽  
Structural Support ◽  
Chromosome Synapsis ◽  
Assembly Mechanism

AbstractThe supramolecular structure of the synaptonemal complex (SC) mediates homologous chromosome synapsis and facilitates the formation of genetic crossovers during meiosis. The mammalian SC is formed of eight coiled-coil proteins which interact in specific subcomplexes and self-assemble into distinct macromolecular arrays that fulfil specific aspects of the SC’s dynamic functional architecture. Here, we report the structure of SC subcomplex SYCE2-TEX12 and its mechanism of self-assembly into fibres that define the SC’s midline longitudinal structure. X-ray crystal structures, electron microscopy, biophysical and mutational analyses reveal that SYCE2-TEX12 is assembled from 2:2 complexes in which TEX12 chains are positioned at either end of a rod-like SYCE2 dimer. These molecular building-blocks assemble laterally into 4:4 complexes, and longitudinally into fibres of potentially limitless length, which acts as string-like threads that wind around one another in intertwined fibres of up to 40-nm in width and several micrometres in length. This hierarchical assembly mechanism is reminiscent of intermediate filament proteins and results in SYCE2-TEX12 fibres that can span the entire chromosome length, thereby providing the underpinning structural support for SC elongation during meiotic chromosome synapsis.

scholarly journals SF-assemblin, the structural protein of the 2-nm filaments from striated microtubule associated fibers of algal flagellar roots, forms a segmented coiled coil.

1993 ◽  
Vol 121 (4) ◽  
pp. 837-845 ◽  
Author(s):  
K Weber ◽  
N Geisler ◽  
U Plessmann ◽  
A Bremerich ◽  
K F Lechtreck ◽  
...  
Keyword(s):  
Self Assembly ◽  
Sequence Similarity ◽  
Coiled Coil ◽  
Major Protein ◽  
Molecular Architecture ◽  
Structural Protein ◽  
Structural Domains ◽  
Distinct Cluster ◽  
Basal Apparatus

The microtubule associated system I fibers of the basal apparatus of the flagellate green alga Spermatozopsis similis are noncontractile and display a 28-nm periodicity. Paracrystals with similar periodicities are formed in vitro by SF-assemblin, which is the major protein component of system I fibers. We have determined the amino acid sequence of SF-assemblin and show that it contains two structural domains. The NH2-terminal 31 residues form a nonhelical domain rich in proline. The rod domain of 253 residues is alpha-helical and seems to form a segmented coiled coil with a 29-residue repeat pattern based on four heptads followed by a skip residue. The distinct cluster of acidic residues at the COOH-terminal end of the motifs (periodicity about 4 nm) may be related to tubulin binding of SF-assemblin and/or its self assembly. A similar structure has been predicted from cDNA cloning of beta-giardin, a protein of the complex microtubular apparatus of the sucking disc in the protozoan flagellate Giardia lamblia. Although the rod domains of SF-assemblin and beta-giardin share only 20% sequence identity, they have exactly the same length and display 42% sequence similarity. These results predict that system I fibers and related microtubule associated structures arise from molecules able to form a special segmented coiled coil which can pack into 2-nm filaments. Such molecules seem subject to a strong evolutionary drift in sequence but not in sequence principles and length. This conservation of molecular architecture may have important implications for microtubule binding.

scholarly journals Luminescent Supramolecular Nano- or Microstructures Formed in Aqueous Media by Amphiphile-Noble Metal Complexes

2020 ◽  
Vol 2020 ◽  
pp. 1-24 ◽  
Author(s):  
Carmen Cretu ◽  
Loredana Maiuolo ◽  
Domenico Lombardo ◽  
Elisabeta I. Szerb ◽  
Pietro Calandra
Keyword(s):  
Noble Metal ◽  
Smart Materials ◽  
Self Assembly ◽  
Noble Metals ◽  
Photophysical Properties ◽  
Aqueous Media ◽  
Molecular Architecture ◽  
Stimuli Responsive ◽  
Panoramic View ◽  
Amphiphilic Molecules

The involvement of metal ions within the self-assembly spontaneously occurring in surfactant-based systems gives additional and interesting features. The electronic states of the metal, together with the bonds that can be established with the organic amphiphilic counterpart, are the factors triggering new photophysical properties. Moreover, the availability of stimuli-responsive supramolecular amphiphile assemblies, able to disassemble in a back-process, provides reversible switching particularly useful in novel approaches and applications giving rise to truly smart materials. In particular, small amphiphiles with an inner distribution, within their molecular architecture, of various polar and apolar functional groups, can give a wide variety of interactions and therefore enriched self-assemblies. If it is joined with the opportune presence and localization of noble metals, whose chemical and photophysical properties are undiscussed, then very interesting materials can be obtained. In this minireview, the basic concepts on self-assembly of small amphiphilic molecules with noble metals are shown with particular reference to the photophysical properties aiming at furnishing to the reader a panoramic view of these exciting problematics. In this respect, the following will be shown: (i) the principles of self-assembly of amphiphiles that involve noble metals, (ii) examples of amphiphiles and amphiphile-noble metal systems as representatives of systems with enhanced photophysical properties, and (iii) final comments and perspectives with some examples of modern applications.

scholarly journals Molecular organization of mammalian meiotic chromosome axis revealed by expansion STORM microscopy

2019 ◽  
Vol 116 (37) ◽  
pp. 18423-18428 ◽  
Author(s):  
Huizhong Xu ◽  
Zhisong Tong ◽  
Qing Ye ◽  
Tengqian Sun ◽  
Zhenmin Hong ◽  
...  
Keyword(s):  
Meiotic Chromosome ◽  
Molecular Organization ◽  
Homologous Chromosomes ◽  
Meiotic Chromosomes ◽  
C Terminus ◽  
Stochastic Optical Reconstruction Microscopy ◽  
Optical Reconstruction ◽  
20 Nm ◽  
Chromosome Axis

During prophase I of meiosis, chromosomes become organized as loop arrays around the proteinaceous chromosome axis. As homologous chromosomes physically pair and recombine, the chromosome axis is integrated into the tripartite synaptonemal complex (SC) as this structure’s lateral elements (LEs). While the components of the mammalian chromosome axis/LE—including meiosis-specific cohesin complexes, the axial element proteins SYCP3 and SYCP2, and the HORMA domain proteins HORMAD1 and HORMAD2—are known, the molecular organization of these components within the axis is poorly understood. Here, using expansion microscopy coupled with 2-color stochastic optical reconstruction microscopy (STORM) imaging (ExSTORM), we address these issues in mouse spermatocytes at a resolution of 10 to 20 nm. Our data show that SYCP3 and the SYCP2 C terminus, which are known to form filaments in vitro, form a compact core around which cohesin complexes, HORMADs, and the N terminus of SYCP2 are arrayed. Overall, our study provides a detailed structural view of the meiotic chromosome axis, a key organizational and regulatory component of meiotic chromosomes.

Self-assembly of Stimuli Responsive Coiled-coil Fibrous Hydrogels

Soft Matter ◽  
2021 ◽  
Author(s):  
Michael Meleties ◽  
Priya Katyal ◽  
Bonnie Lin ◽  
Dustin Britton ◽  
Jin Kim Montclare
Keyword(s):  
Drug Delivery ◽  
Tissue Engineering ◽  
Self Assembly ◽  
Coiled Coil ◽  
Stimuli Responsive ◽  
Tunable Properties ◽  
Stimuli Sensitive ◽  
Biomedical Fields

Owing to their tunable properties, hydrogels comprised of stimuli sensitive polymers are one of the most appealing scaffolds with applications in tissue engineering, drug delivery and other biomedical fields. We...

Protein composition of nuclear matrix preparations from HeLa cells: an immunochemical approach

1986 ◽  
Vol 80 (1) ◽  
pp. 103-122
Author(s):  
R. Verheijen ◽  
H. Kuijpers ◽  
P. Vooijs ◽  
W. van Venrooij ◽  
F. Ramaekers
Keyword(s):  
Nuclear Matrix ◽  
Connective Tissue Diseases ◽  
Protein Composition ◽  
Cytoskeletal Proteins ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis ◽  
Core Proteins ◽  
Nuclear Rna ◽  
Hela S3 ◽  
Protein Components

Procedures for the isolation of HeLa S3 nuclear matrices were re-examined with special emphasis on the use of various nucleases and detergents as well as on the ionic strength of the final salt extraction. The protein composition of the resulting nuclear matrix preparations was analysed by one- and two-dimensional gel electrophoresis and found to be extremely reproducible. By means of co-electrophoresis several typical cytoskeletal proteins (actin, vimentin and cytokeratins) and heterogeneous nuclear RNA (hnRNA)-associated core proteins (hnRNP) were shown to be present in such nuclear matrix preparations. The nature of some other protein components was elucidated using two-dimensional immunoblotting and immunofluorescence. For this purpose mouse monoclonal antibodies to cytoskeletal components (vimentin, cytokeratins), small nuclear RNP (70 X 10(3) Mr protein of U1-RNP), hnRNP (C1/C2) and the pore-complex lamina (lamins A, B and C) were used next to human autoimmune sera obtained from patients with connective tissue diseases and directed against the residual nucleoli and the internal fibrillar mass. These antibodies enabled us to identify a number of proteins present specifically in the nuclear matrix and to show that part of the cytoskeletal proteins are still present in the isolated structures.

Induction of protein-like molecular architecture by self-assembly processes

1999 ◽  
Vol 7 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Gregg B. Fields
Keyword(s):  
Self Assembly ◽  
Molecular Architecture

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.

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