scholarly journals Nucleic Acid-Dependent Cross-Linking of the Nucleocapsid Protein of Sindbis Virus

2000 ◽  
Vol 74 (9) ◽  
pp. 4302-4309 ◽  
Author(s):  
Timothy L. Tellinghuisen ◽  
Richard J. Kuhn
Keyword(s):  
Nucleic Acid ◽  
Capsid Protein ◽  
Nucleocapsid Protein ◽  
Sindbis Virus ◽  
Cross Linking ◽  
Cross Link ◽  
Threefold Axis ◽  
Assembly Pathway ◽  
The Cross

ABSTRACT The assembly of the alphavirus nucleocapsid core is a multistep event requiring the association of the nucleocapsid protein with nucleic acid and the subsequent oligomerization of capsid proteins into an assembled core particle. Although the mechanism of assembly has been investigated extensively both in vivo and in vitro, no intermediates in the core assembly pathway have been identified. Through the use of both truncated and mutant Sindbis virus nucleocapsid proteins and a variety of cross-linking reagents, a possible nucleic acid-protein assembly intermediate has been detected. The cross-linked species, a covalent dimer, has been detected only in the presence of nucleic acid and with capsid proteins capable of binding nucleic acid. Optimum nucleic acid-dependent cross-linking was seen at a protein-to-nucleic-acid ratio identical to that required for maximum binding of the capsid protein to nucleic acid. Identical results were observed when cross-linking in vitro assembled core particles of both Sindbis and Ross River viruses. Purified cross-linked dimers of truncated proteins and of mutant proteins that failed to assemble were found to incorporate into assembled core particles when present as minor components in assembly reactions, suggesting that the cross-linking traps an authentic intermediate in nucleocapsid core assembly. Endoproteinase Lys-C mapping of the position of the cross-link indicated that lysine 250 of one capsid protein was cross-linked to lysine 250 of an adjacent capsid protein. Examination of the position of the cross-link in relation to the existing model of the nucleocapsid core suggests that the cross-linked species is a cross-capsomere contact between a pentamer and hexamer at the quasi-threefold axis or is a cross-capsomere contact between hexamers at the threefold axis of the icosahedral core particle and suggests several possible assembly models involving a nucleic acid-bound dimer of capsid protein as an early step in the assembly pathway.

scholarly journals In Vitro Assembly of Sindbis Virus Core-Like Particles from Cross-Linked Dimers of Truncated and Mutant Capsid Proteins

2001 ◽  
Vol 75 (6) ◽  
pp. 2810-2817 ◽  
Author(s):  
Timothy L. Tellinghuisen ◽  
Rushika Perera ◽  
Richard J. Kuhn
Keyword(s):  
Capsid Protein ◽  
Sindbis Virus ◽  
Terminal Region ◽  
Full Length ◽  
Capsid Proteins ◽  
Size Difference ◽  
Cross Linking ◽  
Cross Link ◽  
Amino Terminal

ABSTRACT A nucleic acid-bound capsid protein dimer was previously identified using a Sindbis virus in vitro nucleocapsid assembly system and cross-linking reagents. Cross-link mapping, in combination with a model of the nucleocapsid core, suggested that this dimer contained one monomer from each of two adjacent capsomeres. This intercapsomere dimer is believed to be the initial intermediate in the nucleocapsid core assembly mechanism. This paper presents the purification of cross-linked dimers of a truncated capsid protein and the partial purification of cross-linked dimers of a full-length assembly-defective mutant. The assembly of core-like particles from these cross-linked capsid protein dimers is demonstrated. Core-like particles generated from cross-linked full-length mutant CP(19-264)L52D were examined by electron microscopy and appeared to have a morphology similar to that of wild-type in vitro-assembled core-like particles, although a slight size difference was often visible. Truncated cross-linked CP(81-264) dimers generated core-like particles as well. These core-like particles could subsequently be disassembled when reversible cross-linking reagents were used to form the dimers. The ability of the covalent intercapsomere cross-link to rescue capsid proteins with assembly defects or truncations in the amino-terminal region of the capsid protein supports the previous model of assembly and suggests a possible role for the amino-terminal region of the protein.

scholarly journals A SEX-LINKED DEFECT IN THE CROSS-LINKING OF COLLAGEN AND ELASTIN ASSOCIATED WITH THE MOTTLED LOCUS IN MICE

1974 ◽  
Vol 139 (1) ◽  
pp. 180-192 ◽  
Author(s):  
David W. Rowe ◽  
Ermona B. McGoodwin ◽  
George R. Martin ◽  
Michael D. Sussman ◽  
Douglas Grahn ◽  
...  
Keyword(s):  
Coat Color ◽  
Cross Linking ◽  
Genetic Abnormality ◽  
Cross Link ◽  
Skin Collagen ◽  
The Cross ◽  
Tissue Abnormalities ◽  
Link Formation ◽  
Experimental Lathyrism

A genetic abnormality in collagen and elastin cross-linking resembling experimental lathyrism has been identified in mice. The defect is an X-linked trait, attributed to the mottled locus which also influences coat color. The affected mice have aneurysms of the aorta and its branches, weak skin, and bone deformities in a spectrum of severity varying with the alleles at the mottled locus. A defect in the cross-linking of collagen was demonstrated in the skin of the affected animals by a marked increase in collagen extractability and a reduced proportion of cross-linked components in the extracted collagen. A decrease in lysine-derived aldehyde levels was found in both skin collagen and aortic elastin similar to that found in lathyritic tissue. Furthermore the in vitro formation of lysine-derived aldehyde was reduced. Thus the cause of the connective tissue abnormalities in these mice appears to be a defect in cross-link formation due to an impairment in aldehyde formation.

scholarly journals Microtubules and microtubule-associated proteins from the nematode Caenorhabditis elegans: periodic cross-links connect microtubules in vitro.

1986 ◽  
Vol 103 (1) ◽  
pp. 23-31 ◽  
Author(s):  
E J Aamodt ◽  
J G Culotti
Keyword(s):  
Caenorhabditis Elegans ◽  
Apparent Molecular Weight ◽  
Cross Link ◽  
Nematode Caenorhabditis Elegans ◽  
Microtubule Associated Proteins ◽  
C Elegans ◽  
Associated Proteins ◽  
Cross Links ◽  
The Cross

The nematode Caenorhabditis elegans should be an excellent model system in which to study the role of microtubules in mitosis, embryogenesis, morphogenesis, and nerve function. It may be studied by the use of biochemical, genetic, molecular biological, and cell biological approaches. We have purified microtubules and microtubule-associated proteins (MAPs) from C. elegans by the use of the anti-tumor drug taxol (Vallee, R. B., 1982, J. Cell Biol., 92:435-44). Approximately 0.2 mg of microtubules and 0.03 mg of MAPs were isolated from each gram of C. elegans. The C. elegans microtubules were smaller in diameter than bovine microtubules assembled in vitro in the same buffer. They contained primarily 9-11 protofilaments, while the bovine microtubules contained 13 protofilaments. The principal MAP had an apparent molecular weight of 32,000 and the minor MAPs were 30,000, 45,000, 47,000, 50,000, 57,000, and 100,000-110,000 mol wt as determined by SDS-gel electrophoresis. The microtubules were observed, by electron microscopy of negatively stained preparations, to be connected by stretches of highly periodic cross-links. The cross-links connected the adjacent protofilaments of aligned microtubules, and occurred at a frequency of one cross-link every 7.7 +/- 0.9 nm, or one cross-link per tubulin dimer along the protofilament. The cross-links were removed when the MAPs were extracted from the microtubules with 0.4 M NaCl. The cross-links then re-formed when the microtubules and the MAPs were recombined in a low salt buffer. These results strongly suggest that the cross-links are composed of MAPs.

EXPERIMENTAL VALIDATION OF THE CHARLESBY AND HORIKX MODELS APPLIED TO DE-VULCANIZATION OF SULFUR AND PEROXIDE VULCANIZATES OF NR AND EPDM

2016 ◽  
Vol 89 (4) ◽  
pp. 671-688 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Experimental Validation ◽  
Main Chain ◽  
Sol Gel ◽  
Chain Scission ◽  
Cross Linking ◽  
Cross Link ◽  
Practical Reality ◽  
Cross Links ◽  
The Cross ◽  
Theoretical Considerations

ABSTRACT The theoretical model developed by Charlesby to quantify the balance between cross-links creation of polymers and chain scission during radiation cross-linking and further modifications by Horikx to describe network breakdown from aging were merged to characterize the balance of both types of scission on the development of the sol content during de-vulcanization of rubber networks. There are, however, disturbing factors in these theoretical considerations vis-à-vis practical reality. Sulfur- and peroxide-cured NR and EPDM vulcanizates were de-vulcanized under conditions of selective cross-link and random main-chain scissions. Cross-link scission was obtained using thiol-amine reagents for selective cleavage of sulfur cross-links. Random main-chain scission was achieved by heating peroxide vulcanizates of NR with diphenyldisulfide, a method commonly employed for NR reclaiming. An important factor in the analyses of these experiments is the cross-linking index. Its value must be calculated using the sol fraction of the cross-linked network before de-vulcanization to obtain reliable results. The values for the cross-linking index calculated with sol-gel data before de-vulcanization appear to fit the experimentally determined modes of network scission during de-vulcanization very well. This study confirms that the treatment of de-vulcanization data with the merged Charlesby and Horikx models can be used satisfactorily to characterize the de-vulcanization of NR and EPDM vulcanizates.

scholarly journals The Effect of Oxidized Dopamine on the Structure and Molecular Chaperone Function of the Small Heat-Shock Proteins, αB-Crystallin and Hsp27

2021 ◽  
Vol 22 (7) ◽  
pp. 3700
Author(s):  
Junna Hayashi ◽  
Jennifer Ton ◽  
Sparsh Negi ◽  
Daniel E. K. M. Stephens ◽  
Dean L. Pountney ◽  
...  
Keyword(s):  
Heat Shock ◽  
Protein Aggregation ◽  
Molecular Chaperone ◽  
Cross Linking ◽  
Αb Crystallin ◽  
The Cross ◽  
Shock Proteins ◽  
And Function

Oxidation of the neurotransmitter, dopamine (DA), is a pathological hallmark of Parkinson’s disease (PD). Oxidized DA forms adducts with proteins which can alter their functionality. αB-crystallin and Hsp27 are intracellular, small heat-shock molecular chaperone proteins (sHsps) which form the first line of defense to prevent protein aggregation under conditions of cellular stress. In vitro, the effects of oxidized DA on the structure and function of αB-crystallin and Hsp27 were investigated. Oxidized DA promoted the cross-linking of αB-crystallin and Hsp27 to form well-defined dimer, trimer, tetramer, etc., species, as monitored by SDS-PAGE. Lysine residues were involved in the cross-links. The secondary structure of the sHsps was not altered significantly upon cross-linking with oxidized DA but their oligomeric size was increased. When modified with a molar equivalent of DA, sHsp chaperone functionality was largely retained in preventing both amorphous and amyloid fibrillar aggregation, including fibril formation of mutant (A53T) α-synuclein, a protein whose aggregation is associated with autosomal PD. In the main, higher levels of sHsp modification with DA led to a reduction in chaperone effectiveness. In vivo, DA is sequestered into acidic vesicles to prevent its oxidation and, intracellularly, oxidation is minimized by mM levels of the antioxidant, glutathione. In vitro, acidic pH and glutathione prevented the formation of oxidized DA-induced cross-linking of the sHsps. Oxidized DA-modified αB-crystallin and Hsp27 were not cytotoxic. In a cellular context, retention of significant chaperone functionality by mildly oxidized DA-modified sHsps would contribute to proteostasis by preventing protein aggregation (particularly of α-synuclein) that is associated with PD.

scholarly journals Improving the Color Stability of Naturally Colored Silk by Cross-Linking the Sericin with Phytic Acid

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Mingbo Ma ◽  
Pirah Ayaz ◽  
Wanhui Jin ◽  
Wenlong Zhou
Keyword(s):  
Phytic Acid ◽  
Color Stability ◽  
Constant Level ◽  
Cross Linking ◽  
Color Fastness ◽  
Cross Link ◽  
Biomedical Field ◽  
The Cross

The color of naturally colored silk (NCS) fades easily during home washing due to the loss of pigment accompanied by dissolution of the sericin. In this study, phytic acid was used to cross-link the sericin of NCS and reduce its solubility, aiming at improving the color fastness of NCS to repeated washing. It was found that the sericin-fixing effect increased as the concentration of phytic acid to 1.0 wt% and the cross-linking time to 5 h increased and then reached a constant level. Cross-linking at pH 7.0-8.5 and temperature 30-40°C could obtain relatively good sericin-fixing effects. The cross-linked NCS showed low sericin loss during the degumming and had much better color fastness to repeated washing as compared with the samples before cross-linking. The cross-linking method proposed in this study may be not only a kind of solution for improving the color fastness of NCS with high practicality but also an alternative for cross-linking sericin-based materials in the biomedical field.

scholarly journals Cross-linking Electrospun Polydioxanone-Soluble Elastin Blends: Material Characterization

2008 ◽  
Vol 3 (1) ◽  
pp. 155892500800300 ◽  
Author(s):  
Michael J. McClure ◽  
Scott A. Sell ◽  
Catherine P. Barnes ◽  
Whitney C. Bowen ◽  
Gary L. Bowlin
Keyword(s):  
Femoral Artery ◽  
Material Properties ◽  
In Vivo Studies ◽  
Uniaxial Tensile ◽  
Cross Linking ◽  
Materials Testing ◽  
Uniaxial Tensile Testing ◽  
The Cross

The purpose of this study was to establish whether material properties of elastin co-electrospun with polydioxanone (PDO) would change over time in both the uncross-linked state and the cross-linked state. First, uncross-linked scaffolds were placed in phosphate buffered saline (PBS) for three separate time periods: 15 minutes, 1 hour, and 24 hours, and subsequently tested using uniaxial materials testing. Several cross-linking reagents were then investigated to verify their ability to crosslink elastin: 1–ethyl-3–(dimethylaminopropyl)-carbodiimide (EDC), ethylene glycol diglycidyl ether (EGDE), and genipin. Uniaxial tensile testing was performed on scaffolds cross-linked with EDC and genipin, yielding results that warranted further investigation for PDO-elastin blends. Material properties of the cross-linked scaffolds were then found within range of both pig femoral artery and human femoral artery. These results demonstrate PDO-elastin blends could potentially be favorable as vascular grafts, thus warranting future in vitro and in vivo studies.

scholarly journals Cross-linking modifications of HDL apoproteins by oxidized phospholipids: structural characterization, in vivo detection, and functional implications

2020 ◽  
Vol 295 (7) ◽  
pp. 1973-1984
Author(s):  
Detao Gao ◽  
Mohammad Z. Ashraf ◽  
Lifang Zhang ◽  
Niladri Kar ◽  
Tatiana V. Byzova ◽  
...  
Keyword(s):  
Density Lipoprotein ◽  
Cross Linking ◽  
Oxidized Phospholipids ◽  
Cross Link ◽  
In Vivo Detection ◽  
Lysine Residues ◽  
Cross Links ◽  
Human Atheroma

Apolipoprotein A-I (apoA-I) is cross-linked and dysfunctional in human atheroma. Although multiple mechanisms of apoA-I cross-linking have been demonstrated in vitro, the in vivo mechanisms of cross-linking are not well-established. We have recently demonstrated the highly selective and efficient modification of high-density lipoprotein (HDL) apoproteins by endogenous oxidized phospholipids (oxPLs), including γ-ketoalkenal phospholipids. In the current study, we report that γ-ketoalkenal phospholipids effectively cross-link apoproteins in HDL. We further demonstrate that cross-linking impairs the cholesterol efflux mediated by apoA-I or HDL3 in vitro and in vivo. Using LC-MS/MS analysis, we analyzed the pattern of apoprotein cross-linking in isolated human HDL either by synthetic γ-ketoalkenal phospholipids or by oxPLs generated during HDL oxidation in plasma by the physiologically relevant MPO-H2O2-NO2− system. We found that five histidine residues in helices 5–8 of apoA-I are preferably cross-linked by oxPLs, forming stable pyrrole adducts with lysine residues in the helices 3–4 of another apoA-I or in the central domain of apoA-II. We also identified cross-links of apoA-I and apoA-II with two minor HDL apoproteins, apoA-IV and apoE. We detected a similar pattern of apoprotein cross-linking in oxidized murine HDL. We further detected oxPL cross-link adducts of HDL apoproteins in plasma and aorta of hyperlipidemic LDLR−/− mice, including cross-link adducts of apoA-I His-165–apoA-I Lys-93, apoA-I His-154–apoA-I Lys-105, apoA-I His-154–apoA-IV Lys-149, and apoA-II Lys-30–apoE His-227. These findings suggest an important mechanism that contributes to the loss of HDL's atheroprotective function in vivo.

scholarly journals Analysis of Venezuelan Equine Encephalitis Virus Capsid Protein Function in the Inhibition of Cellular Transcription

2007 ◽  
Vol 81 (24) ◽  
pp. 13552-13565 ◽  
Author(s):  
Natalia Garmashova ◽  
Svetlana Atasheva ◽  
Wenli Kang ◽  
Scott C. Weaver ◽  
Elena Frolova ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Protein Function ◽  
Sindbis Virus ◽  
New World ◽  
Critical Role ◽  
The United States ◽  
Nuclear Pore ◽  
Cellular Transcription

ABSTRACT The encephalitogenic New World alphaviruses, including Venezuelan (VEEV), eastern (EEEV), and western equine encephalitis viruses, constitute a continuing public health threat in the United States. They circulate in Central, South, and North America and have the ability to cause fatal disease in humans and in horses and other domestic animals. We recently demonstrated that these viruses have developed the ability to interfere with cellular transcription and use it as a means of downregulating a cellular antiviral response. The results of the present study suggest that the N-terminal, ∼35-amino-acid-long peptide of VEEV and EEEV capsid proteins plays the most critical role in the downregulation of cellular transcription and development of a cytopathic effect. The identified VEEV-specific peptide CVEE33-68 includes two domains with distinct functions: the α-helix domain, helix I, which is critically involved in supporting the balance between the presence of the protein in the cytoplasm and nucleus, and the downstream peptide, which might contain a functional nuclear localization signal(s). The integrity of both domains not only determines the intracellular distribution of the VEEV capsid but is also essential for direct capsid protein functioning in the inhibition of transcription. Our results suggest that the VEEV capsid protein interacts with the nuclear pore complex, and this interaction correlates with the protein's ability to cause transcriptional shutoff and, ultimately, cell death. The replacement of the N-terminal fragment of the VEEV capsid by its Sindbis virus-specific counterpart in the VEEV TC-83 genome does not affect virus replication in vitro but reduces cytopathogenicity and results in attenuation in vivo. These findings can be used in designing a new generation of live, attenuated, recombinant vaccines against the New World alphaviruses.

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