The Synaptonemal Complex Protein SCP3 Can Form Multistranded, Cross-striated Fibers In Vivo

The synaptonemal complex protein SCP3 is part of the lateral element of the synaptonemal complex, a meiosis-specific protein structure essential for synapsis of homologous chromosomes. We have investigated the fiber-forming properties of SCP3 to elucidate its role in the synaptonemal complex. By synthesis of SCP3 in cultured somatic cells, it has been shown that SCP3 can self-assemble into thick fibers and that this process requires the COOH-terminal coiled coil domain of SCP3, as well as the NH2-terminal nonhelical domain. We have further analyzed the thick SCP3 fibers by transmission electron microscopy and immunoelectron microscopy. We found that the fibers display a transversal striation with a periodicity of ∼20 nm and consist of a large number of closely associated, thin fibers, 5–10 nm in diameter. These features suggest that the SCP3 fibers are structurally related to intermediate filaments. It is known that in some species the lateral elements of the synaptonemal complex show a highly ordered striated structure resembling that of the SCP3 fibers. We propose that SCP3 fibers constitute the core of the lateral elements of the synaptonemal complex and function as a molecular framework to which other proteins attach, regulating DNA binding to the chromatid axis, sister chromatid cohesion, synapsis, and recombination.

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X-ray crystallographic studies of the middle part of the human synaptonemal complex protein 1 coiled-coil domain

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x15012728 ◽

2015 ◽

Vol 71 (9) ◽

pp. 1131-1134 ◽

Cited By ~ 1

Author(s):

Hyun Ho Park

Keyword(s):

Synaptonemal Complex ◽

Short Form ◽

Complex Structure ◽

Coiled Coil ◽

Middle Part ◽

X Ray ◽

Cell Parameters ◽

Coiled Coil Domain ◽

Complex Protein ◽

Synaptonemal Complex Protein

The synaptonemal complex is a meiosis-specific complex structure formed at the synapse of homologous chromosomes to hold them together during meiosis. Synaptonemal complex protein 1 (SYCP1) is one of the components of the syneptonemal complex. In this study, the short form of the coiled-coil domain of SYCP1 was overexpressed inEscherichia coliwith an engineered C-terminal His tag. The short form of the coiled-coil domain of SYCP1 was then purified to homogeneity and crystallized at 293 K. X-ray diffraction data were collected to a resolution of 3.0 Å from a crystal belonging to space groupI4, with unit-cell parametersa= 41.95,b= 41.95,c= 318.78 Å. The asymmetric unit was estimated to contain two molecules.

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Mice with cleavage-resistant N-cadherin exhibit synapse anomaly in the hippocampus and outperformance in spatial learning tasks

Molecular Brain ◽

10.1186/s13041-021-00738-1 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

M. Asada-Utsugi ◽

K. Uemura ◽

M. Kubota ◽

Y. Noda ◽

Y. Tashiro ◽

...

Keyword(s):

Memory Function ◽

Three Dimensional ◽

Excitatory Synapses ◽

Missense Mutations ◽

Glutamatergic Synapses ◽

Learning Tasks ◽

Transmission Electron ◽

Nmdar Activation ◽

And Function

AbstractN-cadherin is a homophilic cell adhesion molecule that stabilizes excitatory synapses, by connecting pre- and post-synaptic termini. Upon NMDA receptor (NMDAR) activation by glutamate, membrane-proximal domains of N-cadherin are cleaved serially by a-disintegrin-and-metalloprotease 10 (ADAM10) and then presenilin 1(PS1, catalytic subunit of the γ-secretase complex). To assess the physiological significance of the initial N-cadherin cleavage, we engineer the mouse genome to create a knock-in allele with tandem missense mutations in the mouse N-cadherin/Cadherin-2 gene (Cdh2R714G, I715D, or GD) that confers resistance on proteolysis by ADAM10 (GD mice). GD mice showed a better performance in the radial maze test, with significantly less revisiting errors after intervals of 30 and 300 s than WT, and a tendency for enhanced freezing in fear conditioning. Interestingly, GD mice reveal higher complexity in the tufts of thorny excrescence in the CA3 region of the hippocampus. Fine morphometry with serial section transmission electron microscopy (ssTEM) and three-dimensional (3D) reconstruction reveals significantly higher synaptic density, significantly smaller PSD area, and normal dendritic spine volume in GD mice. This knock-in mouse has provided in vivo evidence that ADAM10-mediated cleavage is a critical step in N-cadherin shedding and degradation and involved in the structure and function of glutamatergic synapses, which affect the memory function.

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Microtubule Actin Cross-Linking Factor (Macf)

The Journal of Cell Biology ◽

10.1083/jcb.147.6.1275 ◽

1999 ◽

Vol 147 (6) ◽

pp. 1275-1286 ◽

Cited By ~ 150

Author(s):

Conrad L. Leung ◽

Dongming Sun ◽

Min Zheng ◽

David R. Knowles ◽

Ronald K.H. Liem

Keyword(s):

Calcium Binding ◽

Coiled Coil ◽

Specific Protein ◽

Binding Domain ◽

Full Length ◽

Actin Binding ◽

Cross Linking ◽

Actin Binding Domain

We cloned and characterized a full-length cDNA of mouse actin cross-linking family 7 (mACF7) by sequential rapid amplification of cDNA ends–PCR. The completed mACF7 cDNA is 17 kb and codes for a 608-kD protein. The closest relative of mACF7 is the Drosophila protein Kakapo, which shares similar architecture with mACF7. mACF7 contains a putative actin-binding domain and a plakin-like domain that are highly homologous to dystonin (BPAG1-n) at its NH2 terminus. However, unlike dystonin, mACF7 does not contain a coiled–coil rod domain; instead, the rod domain of mACF7 is made up of 23 dystrophin-like spectrin repeats. At its COOH terminus, mACF7 contains two putative EF-hand calcium-binding motifs and a segment homologous to the growth arrest–specific protein, Gas2. In this paper, we demonstrate that the NH2-terminal actin-binding domain of mACF7 is functional both in vivo and in vitro. More importantly, we found that the COOH-terminal domain of mACF7 interacts with and stabilizes microtubules. In transfected cells full-length mACF7 can associate not only with actin but also with microtubules. Hence, we suggest a modified name: MACF (microtubule actin cross-linking factor). The properties of MACF are consistent with the observation that mutations in kakapo cause disorganization of microtubules in epidermal muscle attachment cells and some sensory neurons.

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Direct regulation of Arp2/3 complex activity and function by the actin binding protein coronin

The Journal of Cell Biology ◽

10.1083/jcb.200206113 ◽

2002 ◽

Vol 159 (6) ◽

pp. 993-1004 ◽

Cited By ~ 126

Author(s):

Christine L. Humphries ◽

Heath I. Balcer ◽

Jessica L. D'Agostino ◽

Barbara Winsor ◽

David G. Drubin ◽

...

Keyword(s):

Binding Protein ◽

Coiled Coil ◽

Actin Binding ◽

Complex Activity ◽

Actin Binding Protein ◽

Coiled Coil Domain ◽

Allele Specific ◽

And Function

Mechanisms for activating the actin-related protein 2/3 (Arp2/3) complex have been the focus of many recent studies. Here, we identify a novel mode of Arp2/3 complex regulation mediated by the highly conserved actin binding protein coronin. Yeast coronin (Crn1) physically associates with the Arp2/3 complex and inhibits WA- and Abp1-activated actin nucleation in vitro. The inhibition occurs specifically in the absence of preformed actin filaments, suggesting that Crn1 may restrict Arp2/3 complex activity to the sides of filaments. The inhibitory activity of Crn1 resides in its coiled coil domain. Localization of Crn1 to actin patches in vivo and association of Crn1 with the Arp2/3 complex also require its coiled coil domain. Genetic studies provide in vivo evidence for these interactions and activities. Overexpression of CRN1 causes growth arrest and redistribution of Arp2 and Crn1p into aberrant actin loops. These defects are suppressed by deletion of the Crn1 coiled coil domain and by arc35-26, an allele of the p35 subunit of the Arp2/3 complex. Further in vivo evidence that coronin regulates the Arp2/3 complex comes from the observation that crn1 and arp2 mutants display an allele-specific synthetic interaction. This work identifies a new form of regulation of the Arp2/3 complex and an important cellular function for coronin.

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Molecular basis for the fold organization and sarcomeric targeting of the muscle atrogin MuRF1

Open Biology ◽

10.1098/rsob.130172 ◽

2014 ◽

Vol 4 (3) ◽

pp. 130172 ◽

Cited By ~ 13

Author(s):

Barbara Franke ◽

Alexander Gasch ◽

Dayté Rodriguez ◽

Mohamed Chami ◽

Muzamil M. Khan ◽

...

Keyword(s):

Ubiquitin Ligase ◽

Quaternary Structure ◽

E3 Ubiquitin Ligase ◽

Coiled Coil ◽

Trim Protein ◽

Muscle Catabolism ◽

And Function ◽

Helical Region ◽

Structural Significance

MuRF1 is an E3 ubiquitin ligase central to muscle catabolism. It belongs to the TRIM protein family characterized by a tripartite fold of RING, B-box and coiled-coil (CC) motifs, followed by variable C-terminal domains. The CC motif is hypothesized to be responsible for domain organization in the fold as well as for high-order assembly into functional entities. But data on CC from this family that can clarify the structural significance of this motif are scarce. We have characterized the helical region from MuRF1 and show that, contrary to expectations, its CC domain assembles unproductively, being the B2- and COS-boxes in the fold (respectively flanking the CC) that promote a native quaternary structure. In particular, the C-terminal COS-box seemingly forms an α-hairpin that packs against the CC, influencing its dimerization. This shows that a C-terminal variable domain can be tightly integrated within the conserved TRIM fold to modulate its structure and function. Furthermore, data from transfected muscle show that in MuRF1 the COS-box mediates the in vivo targeting of sarcoskeletal structures and points to the pharmacological relevance of the COS domain for treating MuRF1-mediated muscle atrophy.

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Phosphorylation of the synaptonemal complex protein SYP-1 promotes meiotic chromosome segregation

10.1101/211672 ◽

2017 ◽

Cited By ~ 1

Author(s):

Aya Sato-Carlton ◽

Chihiro Nakamura-Tabuchi ◽

Stephane Kazuki Chartrand ◽

Tomoki Uchino ◽

Peter Mark Carlton

Keyword(s):

Synaptonemal Complex ◽

Meiotic Chromosome ◽

C Elegans ◽

Chromosome Domains ◽

Chromatid Cohesion ◽

Complex Protein ◽

Chromosomal Passenger ◽

Synaptonemal Complex Protein ◽

A Site ◽

Meiosis I

AbstractChromosomes that have undergone crossing-over in meiotic prophase must maintain sister chromatid cohesion somewhere along their length between the first and second meiotic divisions. While many eukaryotes use the centromere as a site to maintain cohesion, the holocentric organism C. elegans instead creates two chromosome domains of unequal length termed the short arm and long arm, which become the first and second site of cohesion loss at meiosis I and II. The mechanisms that confer distinct functions to the short and long arm domains remain poorly understood. Here, we show that phosphorylation of the synaptonemal complex protein SYP-1 is required to create these domains. Once crossovers are made, phosphorylated SYP-1 and PLK-2 become cooperatively confined to short arms and guide phosphorylated histone H3 and the chromosomal passenger complex to the site of meiosis I cohesion loss. Our results show that PLK-2 and phosphorylated SYP-1 ensure creation of the short arm subdomain, promoting disjunction of chromosomes in meiosis I.

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The extracellular matrix of the developing cornea: diversity, deposition and function*

Development ◽

10.1242/dev.103.supplement.195 ◽

1988 ◽

Vol 103 (Supplement) ◽

pp. 195-205

Author(s):

J. B. L. Bard ◽

M. K. Bansal ◽

A. S. A. Ross

Keyword(s):

Extracellular Matrix ◽

Chondroitin Sulphate ◽

Corneal Stroma ◽

Experimental System ◽

Collagen I ◽

And Function ◽

20 Nm

This paper examines the role of the extracellular matrix (ECM) in the development of the cornea. After a brief summary of the corneal structure and ECM, we describe evidence suggesting that the differentiation of neural crest (NC) cells into endothelium and fibroblasts is under the control of ocular ECM. We then examine the role of collagen I in stromal morphogenesis by comparing normal corneas with those of homozygous Movl3 mice which do not make collagen I. We report that, in spite of this absence, the cellular morphology of the Movl3 eye is indistinguishable from that of the wild type. In the 16-day mutant stroma, however, the remaining collagens form small amounts of disorganized, thin fibrils rather than orthogonally organized 20 nm-diameter fibrils; a result implying that collagen I plays only a structural role and that its absence is not compensated for. It also suggests that, because these remaining collagens will not form the normal fibrils that they will in vitro, fibrillogenesis in the corneal stroma differs from that elsewhere. The latter part of the paper describes our current work on chick stromal deposition using corneal epithelia isolated with an intact basal lamina that lay down in vitro ∼3μm-thick stromas of organized fibrils similar to that seen in vivo. This experimental system has yielded two unexpected results. First, the amount of collagen and proteoglycans produced by such epithelia is not dependent on whether its substratum is collagenous and we therefore conclude that stromal production by the intact epithelium is more autonomous than hitherto thought. Second, chondroitin sulphate (CS), the predominant proteoglycan, appears to play no role in stromal morphogenesis: epithelia cultured in testicular hyaluronidase, which degrades CS, lay down stromas whose organization and fibrildiameter distribution are indistinguishable from controls. One possible role for CS, however, is as a lubricant which facilitates corneal growth: it could allow fibrils to move over one another without deforming their orthogonal organization. Finally, we have examined the processes of fibrillogenesis in the corneal stroma and conclude that they are different from those elsewhere in the embryo and in vitro, perhaps because there is in the primary stroma an unidentified, highly hydrated ECM macromolecule that embeds the fibrils and that may mediate their morphogenesis.

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