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At least 721 records · Page 40Linked to original sources
PubMed2000

Hepatitis delta virus replication generates complexes of large hepatitis delta antigen and antigenomic RNA that affiliate with and alter nuclear domain 10.

Hepatitis delta virus (HDV), a single-stranded RNA virus, bears a single coding region whose product, the hepatitis delta antigen (HDAg), is expressed in two isoforms, small (S-HDAg) and large (L-HDAg). S-HDAg is required for replication of HDV, while L-HDAg inhibits viral replication and is required for the envelopment of the HDV genomic RNA by hepatitis B virus proteins. Here we have examined the spatial distribution of HDV RNA and proteins in infected nuclei, with particular reference to specific nuclear domains. We found that L-HDAg was aggregated in specific nuclear domains and that over half of these domains were localized beside nuclear domain 10 (ND10). At later times, ND10-associated proteins like PML were found in larger HDAg complexes that had developed into apparently hollow spheres. In these larger complexes, PML was found chiefly in the rims of the spheres, while the known ND10 components Sp100, Daxx, and NDP55 were found in the centers of the spheres. Thus, ND10 proteins that normally are closely linked separate within HDAg-associated complexes. Viral RNA of antigenomic polarity, whether expressed from genomic RNA or directly from introduced plasmids, colocalizes with L-HDAg and the transcriptional repressor PML. In contrast, HDV genomic RNA was distributed more uniformly throughout the nucleus. These results suggest that different host protein complexes may assemble on viral RNA strands of different polarities, and they also suggest that this RNA virus, like DNA viruses, can alter the distribution of ND10-associated proteins. The fact that viral components specifically linked to repression of replication can associate with one of the ND10-associated proteins (PML) raises the possibility that this host protein may play a role in the regulation of HDV RNA synthesis.

Adaptor Proteins, Signal Transducing↗
PubMed1986

A gene expressed in undifferentiated vegetative Dictyostelium is repressed by developmental pulses of cAMP and reinduced during dedifferentiation.

We describe the gene M4-1, whose unique pattern of developmental expression will allow us to study the molecular mechanisms controlling expression in undifferentiated cells in addition to repression in response to cAMP during development and reinduction during dedifferentiation. M4-1 is a Dictyostelium gene expressed in the undifferentiated cell. We have shown that M4-1 continues to be expressed very early during the developmental cycle but is repressed at a later stage of development, at a time coincident with the establishment of oscillations in the cAMP pool. Studies on the expression of the M4-1 gene in shaking culture, under conditions that mimic early development, have established that pulsatile stimulation of cells with cAMP is sufficient to repress M4-1 expression. Consistent with this, cells that are exposed to high levels of cAMP are unable to respond normally to cAMP oscillations and continue to express M4-1 at vegetative levels. These data indicate that low-level oscillations of cAMP are required for the repression of M4-1 expression rather than the continuous high levels of cAMP responsible for the regulation of a different class of Dictyostelium genes. We suggest that cAMP may mediate developmental expression of the Dictyostelium genome by different mechanisms. We also show that cell-cell interaction, a developmental event that occurs subsequent to the cAMP pulse, does not normally influence the regulation of M4-1. Finally, we have shown that when cAMP-pulsed cells are induced to dedifferentiate, M4-1 RNA sequences rapidly reappear in nuclei and cytoplasm, suggesting that regulation of M4-1 expression is primarily mediated at the level of transcription.

Cell Aggregation↗
PubMed2025

Utility of genome sequencing and group-enrichment to support splice variant interpretation in Marfan syndrome.

PURPOSE: To quantify the impact of noncanonical FBN1 splice site variants in undiagnosed Marfan syndrome (MFS), a connective tissue disorder associated with skeletal abnormalities and familial thoracic aortic aneurysm disease (FTAAD). METHODS: A systematic analysis of ultrarare FBN1 variants was performed using genome sequencing data from the 100,000 Genomes Project. Variants were annotated with SpliceAI and the significance of enrichment among individuals with FTAAD was assessed using Fisher's exact test. Experimental validation used RNA sequencing, reverse transcriptase polymerase chain reaction, minigene constructs, and replication analysis was with data from UK Biobank. RESULTS: Using aggregate data for 78,195 individuals, we identified 13,864 singleton single-nucleotide variants in FBN1 of which 21 were predicted to affect splicing (SpliceAI > 0.5). Incidence of candidate splice variants in individuals recruited with FTAAD (9/703) was significantly elevated compared with that seen in non-FTAAD participants (12/77,492; odds ratio = 84, P = 9.7 × 10-14). Additional analysis uncovered a further 14 families harboring 11 different FBN1 splice variants. A total of 20 candidate splice variants in 23 families were identified, of which 70% lay beyond the ±8 splice regions. RNA testing confirmed the predicted splice aberration in 16 of 20 and for 9 of 20, pseudoexonization was the likely splicing anomaly. CONCLUSION: Our findings indicate that noncanonical splice variants may account for approximately 3% of families with undiagnosed FTAAD, highlighting the importance of incorporating analysis of introns and confirmatory RNA testing into genetic testing for Marfan syndrome.

Humans↗
PubMed2002

Von Willebrand factor-cleaving protease and Upshaw-Schulman syndrome.

Vascular endothelial cell (EC)-produced plasma von Willebrand factor (vWF) plays a critical role in primary hemostasis through its action of anchoring platelets onto the injured denuded subendothelial matrices under high shear stress. Unusually large vWF multimers (UL-vWFMs), present in plasma immediately after release from ECs, are most biologically active, but they are soon cleaved and degraded into smaller vWFMs by a specific plasma protease, termed vWF-cleaving protease (vWF-CPase), in normal circulation. Recent studies on the relationship between UL-vWFMs and vWF-CPase, together with its autoantibody (inhibitor) have brought about a clear discrimination between thrombotic thrombocytopenic purpura and hemolytic uremic syndrome. Furthermore, a congenital deficiency of this enzyme activity has been shown to cause Upshaw-Schulman syndrome, a complex constitutional bleeding diathesis. Successful purification of vWF-CPase revealed that this enzyme is composed of a single polypeptide with a molecular mass of approximately 190 kd, and its complementary DNA cloning unambiguously indicated that it is uniquely produced in the liver and its gene is located on chromosome 9q34. The messenger RNA of vWF-CPase had a span of 4.6 kb, and its enzyme was designated ADAMTS 13. The predicted complete amino acid sequence of this enzyme consisted of 1427 residues, including a signal peptide, a short propeptide terminating in the sequence RQRR, a reprolysin-like metalloprotease domain, a disintegrin-like domain, a thrombospondin-1 repeat (TSP1), a cysteine-rich domain, an ADAMTS spacer, 7 additional TSP1 repeats, and 2 CUB domains.

ADAM Proteins↗
PubMed2004

Epidermal growth factor receptor regulates aberrant expression of insulin-like growth factor-binding protein 3.

Epidermal growth factor receptor (EGFR) is frequently overexpressed in esophageal carcinoma and its precursor lesions. To gain insights into how EGFR overexpression affects cellular functions in primary human esophageal cells, we performed gene expression profiling and identified insulin-like growth factor-binding protein (IGFBP)-3 as the most up-regulated gene. IGFBP-3 regulates cell proliferation through both insulin-like growth factor-dependent and independent mechanisms. We found that IGFBP-3 mRNA and protein expression was increased in EGFR-overexpressing primary and immortalized human esophageal cells. IGFBP-3 was also up-regulated in EGFR-overexpressing cells in organotypic culture and in EGFR transgenic mice. Furthermore, IGFBP-3 mRNA was overexpressed in 80% of primary esophageal squamous cell carcinomas and 60% of primary esophageal adenocarcinomas. Concomitant up-regulation of EGFR and IGFBP-3 was observed in 60% of primary esophageal squamous cell carcinomas. Immunohistochemistry revealed cytoplasmic localization of IGFBP-3 in the preponderance of preneoplastic and neoplastic esophageal lesions. IGFBP-3 was also overexpressed in esophageal cancer cell lines at both mRNA (60%) and protein (40%) levels. IGFBP-3 secreted by cancer cells was capable of binding to insulin-like growth factor I. Functionally, epidermal growth factor appeared to regulate IGFBP-3 expression in esophageal cancer cell lines. Finally, suppression of IGFBP-3 by small interfering RNA augmented cell proliferation, suggesting that IGFBP-3 may inhibit tumor cell proliferation as a negative feedback mechanism. In aggregate, we have identified for the first time that IGFBP-3 is an aberrantly regulated gene through the EGFR signaling pathway and it may modulate EGFR effects during carcinogenesis.

Animals↗
PubMed1980

Studies dealing with hepatic RNA metabolism in rats force-fed a threonine-devoid diet.

Young rats were force-fed for 3 days a purified diet devoid of threonine and a number of aspects relating to RNA metabolism in the livers were studied. The findings in the livers of rats force-fed the threonine-devoid diet in comparison with those force-fed the complete diet were as follows: a) poly(A)-mRNA was increased in nuclei and in polyribosomes; b) DNA-dependent RNA polymerases I and II activities were increased; c) in vitro release of 14C-orotic acid labeled RNA from nuclei revealed that transport was unchanged and nucleoside triphosphatase activity of nuclear envelopes was unchanged; d) polyribosomes (total, free and membrane-bound) shifted toward heavier aggregation and in vitro 14C-leucine incorporation into protein was increased; e) RNase activities (at pH 5.4, 7.6, 9.5) were essentially unaltered; and f) in vivo 14C-choline incorporation into microsomal membranes was increased. By administering selected inhibitors of RNA and protein synthesis, such as actinomycin D, alpha-amanitin or cycloheximide, prior to killing the rats force-fed the threonine-devoid or complete diet for 3 days, it was demonstrated that the stimulatory effect on hepatic polyribosomes and protein synthesis in the experimental group was dependent upon new synthesis of poly(A)mRNA and of protein.

Animals↗
PubMed2005

The neurofibromatosis type 1 gene product neurofibromin enhances cell motility by regulating actin filament dynamics via the Rho-ROCK-LIMK2-cofilin pathway.

Neurofibromin is a neurofibromatosis type 1 (NF1) tumor suppressor gene product with a domain that acts as a GTPase-activating protein and functions, in part, as a negative regulator of Ras. Loss of neurofibromin expression in NF1 patients is associated with elevated Ras activity and increased cell proliferation, predisposing to a variety of tumors of the peripheral and central nervous systems. We show here, using the small interfering RNA (siRNA) technique, that neurofibromin dynamically regulates actin cytoskeletal reorganization, followed by enhanced cell motility and gross cell aggregation in Matrigel matrix. NF1 siRNA induces characteristic morphological changes, such as excessive actin stress fiber formation, with elevated negative phosphorylation levels of cofilin, which regulates actin cytoskeletal reorganization by depolymerizing and severing actin filaments. We found that the elevated phosphorylation of cofilin in neurofibromin-depleted cells is promoted by activation of a Rho-ROCK-LIMK2 pathway, which requires Ras activation but is not transduced through three major Ras-mediated downstream pathways via Raf, phosphatidylinositol 3-kinase, and RalGEF. In addition, the exogenous expression of the NF1-GTPase-activating protein-related domain suppressed the NF1 siRNA-induced phenotypes. Neurofibromin was demonstrated to play a significant role in the machinery regulating cell proliferation and in actin cytoskeletal reorganization, which affects cell motility and adhesion. These findings may explain, in part, the mechanism of multiple neurofibroma formation in NF1 patients.

Actin Depolymerizing Factors↗
PubMed2005

Polyglutamine expansion of huntingtin impairs its nuclear export.

Proteins with polyglutamine (polyQ) expansions accumulate in the nucleus and affect gene expression. The mechanism by which mutant huntingtin (htt) accumulates intranuclearly is not known; wild-type htt, a 350-kDa protein of unknown function, is normally found in the cytoplasm. N-terminal fragments of mutant htt, which contain a polyQ expansion (>37 glutamines), have no conserved nuclear localization sequences or nuclear export sequences but can accumulate in the nucleus and cause neurological problems in transgenic mice. Here we report that N-terminal htt shuttles between the cytoplasm and nucleus in a Ran GTPase-independent manner. Small N-terminal htt fragments interact with the nuclear pore protein translocated promoter region (Tpr), which is involved in nuclear export. PolyQ expansion and aggregation decrease this interaction and increase the nuclear accumulation of htt. Reducing the expression of Tpr by RNA interference or deletion of ten amino acids of N-terminal htt, which are essential for the interaction of htt with Tpr, increased the nuclear accumulation of htt. These results suggest that Tpr has a role in the nuclear export of N-terminal htt and that polyQ expansion reduces this nuclear export to cause the nuclear accumulation of htt.

Amino Acid Sequence↗
PubMed2006

Structure and function of primitive immunoglobulin superfamily neural cell adhesion molecules: a lesson from studies on planarian.

Precise wiring and proper remodeling of the neural network are essential for its normal function. The freshwater planarian is an attractive animal in which to study the formation and maintenance of the neural network due to its high regenerative capability and developmental plasticity. Although a recent study revealed that homologs of netrin and its receptors are required for regeneration and maintenance of the planarian central nervous system (CNS), the roles of cell adhesion in the formation and maintenance of the planarian neural network remain poorly understood. In the present study, we found primitive immunoglobulin superfamily cell adhesion molecules (IgCAMs) in a planarian that are homologous to vertebrate neural IgCAMs. We identified planarian orthologs of NCAM, L1CAM, contactin and DSCAM, and designated them DjCAM, DjLCAM, DjCTCAM and DjDSCAM, respectively. We further confirmed that they function as cell adhesion molecules using cell aggregation assays. DjCAM and DjDSCAM were found to be differentially expressed in the CNS. Functional analyses using RNA interference revealed that DjCAM is partly involved in axon formation, and that DjDSCAM plays crucial roles in neuronal cell migration, axon outgrowth, fasciculation and projection.

Animals↗
PubMed1989

Form-determining functions in Sindbis virus nucleocapsids: nucleosomelike organization of the nucleocapsid.

Purified intact Sindbis virus nucleocapsids were treated at different pH values or with various concentrations of divalent cations, cation chelators, salt, or formamide. The resulting structures were examined by velocity sedimentation, electron microscopy, and protein-protein cross-linking. Changes in each of the test conditions led to alterations in the sedimentation profile of treated nucleocapsids. Appropriate concentrations of formamide or divalent cations generated beaded strandlike structures similar in morphology to those generated from adenovirus cores and nucleosomes. The capsid protein and RNA remained associated with each other at NaCl concentrations less than or equal to 1 M or after treatment of the structures with alkaline pH up to and including pH 10.7. Protein and RNA were dissociated by salt concentrations of greater than 1 M, suggesting that the arginine-rich, amino-terminal portion of the capsid protein is responsible for binding the RNA. Protein-protein cross-linking also indicated that the capsid proteins remained associated in small aggregates under some of the conditions that caused dissociation of the nucleocapsid and suggested the presence of more than one type of protein-protein interaction in the nucleocapsids. Collectively, these data suggest that, like histones and adenovirus core proteins, the Sindbis virus capsid protein serves to package segments of the genome into nucleoprotein beads which are capable of interacting with each other to form the nucleocapsid structure.

Capsid↗
PubMed1963

CHEMICAL AND PHYSICAL CHARACTERIZATION OF "NUCLEAR CAPS" ISOLATED FROM BLASTOCLADIELLA ZOOSPORES.

Lovett, James S. (Purdue University, West Lafayette, Ind.). Chemical and physical characterization of "nuclear caps" isolated from Blastocladiella zoospores. J. Bacteriol. 85:1235-1246. 1963.-Electron micrographs of Blastocladiella zoospores have shown the nuclear cap to contain essentially all of the small (250 to 300 A) electron-dense particles of the cell. Preparations of clean, whole nuclear caps were isolated to study the composition of the intact organelles and their particulate contents. The cap is strongly basophilic, and is composed of 60% protein and 40% ribonucleic acid (RNA). It represents 18% of the dry weight, and contains 69% of the total RNA, of the spore. The amino acid composition of cap proteins is similar to the ribosomal protein of other organisms. The nuclear cap contents have been extracted and isolated by high-speed centrifugation. More than 95% of the material has a sedimentation coefficient of 83S in 0.005 m Mg. The 83S particles form aggregates at higher Mg concentrations and dissociate to yield 63S and 41S peaks at low Mg concentrations. Purified cap particles contain 37% protein and 63% RNA. The RNA has a nucleotide composition (in moles per cent) of 18.5% cytidylic, 26.2% adenylic, 31.8% guanylic, and 23.5% uridylic acid. The particles contain a latent ribonuclease, which can be activated by urea, and are susceptible to degradation by added pancreatic ribonuclease. The available evidence supports a concept of the zoospore nuclear cap as an unusual intracellular "packet" of ribosomes.

Amino Acids↗
PubMedDate not supplied

Stimulation of oligodendrocyte differentiation in culture by growth in the presence of a monoclonal antibody to sulfated glycolipid.

Perturbation of myelinogenesis by monoclonal antibodies against galactolipids is being used to study the role of these lipids in oligodendrocyte differentiation. We report here a marked stimulatory effect on oligodendrocyte differentiation when mixed primary cultures initiated from 19-21 day fetal rat telencephala are grown in the presence of a monoclonal antibody against sulfogalactolipids. When such cultures were grown in the presence of the IgM antibody 04 [Sommer and Schachner, Dev Biol 83:311-327 1981], the oligodendrocytes formed aggregates connected by fasciculated processes. Immunofluorescence microscopy and biochemical analyses of treated cultures demonstrated 2-3 fold increases in the fraction of 04-positive cells expressing myelin basic protein, and in the levels of myelin basic protein RNA, myelin basic protein, 2',3'-cyclic nucleotide 3'-phosphohydrolase activity, and 35SO4 incorporation into sulfatide. Greater than 90% of the cells positive for myelin basic protein in treated cultures were in aggregates. The specific activities of oligodendrocyte markers were unaffected in control cultures grown with nonspecific myeloma IgM. Since there was no increase in the total number of 04-positive cells in treated cultures, the increases in the specific activities of the myelin protein markers appears to be due to an increase in the fraction of cells expressing these markers. Time course studies demonstrated that both the rate and extent of oligodendrocyte differentiation were enhanced in treated cultures. These data are discussed with regard to possible mechanisms of the stimulation, considering not only potential direct effects of the antibody on the cell physiology, but also possible indirect effects due to antibody-induced aggregation.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1998

The movement protein of cucumber mosaic virus traffics into sieve elements in minor veins of nicotiana clevelandii

The location of the 3a movement protein (MP) of cucumber mosaic virus (CMV) was studied by quantitative immunogold labeling of the wild-type 3a MP in leaves of Nicotiana clevelandii infected by CMV as well as by using a 3a-green fluorescent protein (GFP) fusion expressed from a potato virus X (PVX) vector. Whether expressed from CMV or PVX, the 3a MP targeted plasmodesmata and accumulated in the central cavity of the pore. Within minor veins, the most extensively labeled plasmodesmata were those connecting sieve elements and companion cells. In addition to targeting plasmodesmata, the 3a MP accumulated in the parietal layer of mature sieve elements. Confocal imaging of cells expressing the 3a-GFP fusion protein showed that the 3a MP assembled into elaborate fibrillar formations in the sieve element parietal layer. The ability of 3a-GFP, expressed from PVX rather than CMV, to enter sieve elements demonstrates that neither the CMV RNA nor the CMV coat protein is required for trafficking of the 3a MP into sieve elements. CMV virions were not detected in plasmodesmata from CMV-infected tissue, although large CMV aggregates were often found in the parietal layer of sieve elements and were usually surrounded by 3a MP. These data suggest that CMV traffics into minor vein sieve elements as a ribonucleoprotein complex that contains the viral RNA, coat protein, and 3a MP, with subsequent viral assembly occurring in the sieve element parietal layer.

Journal Article↗
PubMed2005

Early steps of clathrin-mediated endocytosis involved in phagosomal escape of Fcgamma receptor-targeted adenovirus.

Adenovirus type 2 (Ad2) and Ad5 enter epithelial cells via the coxsackievirus B Ad receptor (CAR) and alpha(v) integrin coreceptors. In the absence of CAR, they can be directed to the Fcgamma receptor 1 of hematopoietic cells by an adaptor comprising the extracellular CAR domain and the Fc portion of a human immunoglobulin G (CARex-Fc). This gives rise to Ad aggregates and single particles which together enhance gene delivery up to 250-fold compared to adaptor-less viruses. A small interfering RNA knockdown of the clathrin heavy chain and quantitative electron microscopy of hematopoietic leukemia cells showed that the majority of Ads were phagocytosed as clusters of 1 to 3 microm in diameter and that about 10% of the particles entered cells by clathrin-mediated endocytosis. The clathrin knockdown did not affect phagocytosis but, surprisingly, inhibited viral escape from phagosomes. Similarly, blocking an early stage of clathrin-coated pit assembly inhibited phagosomal escape and infection but not aggregate uptake, unlike blocking of a late stage of clathrin-coated pit formation. We propose a cooperative interaction of clathrin-mediated endocytosis and phagocytosis triggering phagosomal lysis and infection.

Adenoviruses, Human↗
PubMed1980

The presence of RNA in a double helix inhibits its interaction with histone protein.

The binding of core histones (H2A, H2B, H3, H4) to a circular plasmid DNA and to a circular DNA-RNA hybrid molecule of similar size has been compared. Circular hybrid molecules were formed from single stranded fd DNA by synthesis of the complimentary strand with ribonucleotides using wheat germ RNA polymerase II. Upon reconstitution of plasmid DNA circles with histone, the sedimentation profiles of the DNA remained sharp by increased several fold in rate. Material from the peak fractions of these sedimentations appeared to be condensed circular loops of nucleosomes when examined by electron microscopy (EM), and the mass ratio of DNA to histone (at the histone concentrations which produced the fastest sedimentations) was typical of native chromatin. In contrast, the sedimentation behavior of DNA-RNA hybrid circles after addition of histone remained unchanged except for a minor fraction which exhibited a broad and faster sedimentation rate. Examination by EM revealed that most of the molecules appeared identical to protein free hybrid circles while the minor, faster sedimenting fraction appeared to be two or more circles bound together by protein aggregates. Finally, a linear molecule consisting of about 3000 base pairs of duplex DNA covalently joined on both ends to 1500 base pairs of RNA-DNA hybrid helix was constructed. Reconstitution of this molecule with core histone showed nucleosome formation only on the central DNA duplex region. Isopycnic banding of fixed hybrid-histone mixtures showed that little or no histone had bound to the bulk of the full hybrid molecules. We suggest that the presence of RNA in a nucleic acid duplex inhibits the condensation of the duplex into a nucleosomal structure by histone.

Chromosome Banding↗
PubMed2005

RNA selectively interacts with vesicles depending on their size.

RNA and vesicles are two important molecular classes in the origin of life and early evolution, but they are not generally considered as interacting partners. The present paper reports about the interaction between tRNA (Esherichia coli) and vesicles made of the zwitterionic surfactant POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine), partially positively charged with small molar fractions (max 10%) of the single-chained CTAB (cetyltrimethylammonium bromide). CTAB is capable to insert efficiently in POPC vesicles (as determined by zeta-potential measurements), and the binding of tRNA to such charged vesicles operates a strong selection being critically dependent upon the vesicle size. The binding of tRNA to the vesicles is size-selective as it induces a strongly pronounced process of aggregation of large vesicles (ca. 160-nm diameter) but not of small ones (ca. 80-nm diameter) that are stable against vesicle aggregation (as followed by dynamic light-scattering and optical density measurements). The aggregation of the large vesicles is fully reversible upon the addition of RNase A. The selective behavior of tRNA with respect to differently sized vesicles is observable in separated samples as well as in a mixture of both populations. In the latter case, the fraction of large vesicles readily aggregates in the presence of the small ones that remain unaltered in the mixture. This kind of discrimination capability of RNA might have been of importance in the early phases of the formation of the protocells.

Cetrimonium↗
PubMed2001

The formation of empty shells upon pressure induced decapsidation of turnip yellow mosaic virus.

The stability of turnip yellow mosaic virus (TYMV) was investigated under pressure, using solution neutron small angle scattering. Dissociation products were characterized by analytical ultracentrifugation and electron microscopy. At pH 6.0, TYMV remained unaffected by pressure, up to 260 Megapascals (MPa), the highest pressure reached in these experiments. At pH 8.0, TYMV remained unaffected by pressure up to 160 MPa, but decapsidated irreversibly above 200 MPa, giving rise to more and more empty shells upon increasing pressure. The organization of these empty shells was similar to that of the capsid of native virions, apart from the presence of a hole corresponding to the loss of a group of 5-8 coat protein subunits, through which the RNA may have escaped. At variance with other small isometric viruses, the capsid of TYMV never dissociated under pressure into subunits or small aggregates of subunits. This exceptional behavior of TYMV is probably due to the importance of van der Waals contacts and hydrogen bonds in the stability of its capsid.

Capsid↗