Viruses Tobacco mosaic

Gels with Long-Range Forces 1. Tobacco Mosaic Virus 

In these fully oriented gels, easily recognizable rigidity is manifested at a concentration of about 30%, and increases with increasing concentration its appearance is not abrupt, and it is possible that sensitive 

While addition of water to a fully oriented gel results in increased swelling of the lattice without limit and eventual dissolution, in some other solvents there is an equilibrium separation which is not exceeded. Decreasing the pH to the isoelectric point (3.4), for example, or addition of ammonium sulfate to a concentration of 3 M, reduces the equilibrium separation to about 180 A. with the formation of a rather densely packed hexagonal array. 

When the molecules in a 4% solution of virus are oriented by flow, and the pH is lowered by addition of acid, the molecules assume their 

The only intermolecular forces which can act over the distances which the X-ray evidence reveals are coulombic. Since the virus molecules are all negatively charged in the systems described, the electrostatic forces between them should be repulsive. It is reasonable that such forces between rod-shaped molecules should lead to a hexagonal array in order to fill the available space as efficiently as possible, and that the spacing should increase progressively upon dilution, as observed for gels in the absence of salt. The existence of mi equilibrium spacing in the presence of salt is more difficult to understand it has been discussed by Levine (1939, 1941) and Hamaker (1946). 

2 Polypeptide Expression Systems 4.2.2.1 Tobacco Mosaic Virus 

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Bloomer, A.C., et al. Protein disk of tobacco mosaic virus at 2.8 A resolution showing the interactions within and between subunits. Nature TIB-. 362-368, 1978. 

A nucleic acid can never code for a single protein molecule that is big enough to enclose and protect it. Therefore, the protein shell of viruses is built up from many copies of one or a few polypeptide chains. The simplest viruses have just one type of capsid polypeptide chain, which forms either a rod-shaped or a roughly spherical shell around the nucleic acid. The simplest such viruses whose three-dimensional structures are known are plant and insect viruses the rod-shaped tobacco mosaic virus, the spherical satellite tobacco necrosis virus, tomato bushy stunt virus, southern bean mosaic vims. 

Antiparallel tt-helix proteins are structures heavily dominated by a-helices. The simplest way to pack helices is in an antiparallel manner, and most of the proteins in this class consist of bundles of antiparallel helices. Many of these exhibit a slight (15°) left-handed twist of the helix bundle. Figure 6.29 shows a representative sample of antiparallel a-helix proteins. Many of these are regular, uniform structures, but in a few cases (uteroglobin, for example) one of the helices is tilted away from the bundle. Tobacco mosaic virus protein has small, highly... 

Extracts from 152 plant species, representing 46 different families, were screened for effects on tobacco mosaic virus (TMV) replication in cucumber cotyledons. Twenty species have shown enough activity to warrant further study. Several members of the Caprifoliaceae family increased virus replication. An extract of Lonicera involucrata enlarged the virus lesions in local lesion hosts and produced a thirty fold increase in virus titer, but had no effect on virus replication in systemic hosts. The active material appears to affect the virus defense mechanism of local lesion hosts. An extract of common geranium is an active virus inhibitor. It inactivates TMV and TMV-RNA (ribonucleic acid) in vitro by forming non-infectious complexes. In vivo, it also inhibited starch lesion formation in cucumber cotyledons incited by TMV infection. 

Cucumber cotyledons were inoculated with purified tobacco mosaic virus (TMV) 20 to 24 hours before vacuum infiltration with different concentrations of crude water extracts of plant leaves (4). After 7 days, inoculated leaves were harvested and stored 24 hours in the dark in a moist chamber to remove excess starch. Starch lesions were counted after clearing with alcohol and staining with an iodine-potassium iodide-lactic acid mixture. The inhibitory effects of various extracts were demonstrated by comparing lesion counts of treated cotyledons to counts on control cotyledons. 

Fraser, R.S.S. (1982). Are pathogenesis-related proteins involved in acquired systemic resistance of tobacco plants to tobacco mosaic virus Journal of General Virology, 58, 305-13. 

Whenham, R.J., Fraser, R.S.S., Brown, L.P. Payne, J.A. (1986). Tobacco-mosaic-virus-induced increase in abscisic-acid concentration in tobacco leaves Intracellular location in light and dark-green areas, and relationship to symptom development. Planta, 168, 592-8. 

Some virus particles have their protein subunits symmetrically packed in a helical array, forming hollow cylinders. The tobacco mosaic virus (TMV) is the classic example. X-ray diffraction data and electron micrographs have revealed that 16 subunits per turn of the helix project from a central axial hole that runs the length of the particle. The nucleic acid does not lie in this hole, but is embedded into ridges on the inside of each subunit and describes its own helix from one end of the particle to the other. 

Putting aside such considerations, the reader is encouraged to examine the sections of Klug s Nobel Lecture 1W) dealing with the structure and the growth of Tobacco Mosaic Virus to see how helical structures and concepts of inclusion phenomena can relate to molecular biology. 

Santos NC and Castanho MARB. 1996. Teaching light scattering spectroscopy The dimension and shape of tobacco mosaic virus. Biophysical Journal 71(3) 1641-1650. 

Yi L, Shi J, Gao S et al (2009) Sulfonium alkylation followed by click chemistry for facile surface modification of proteins and tobacco mosaic virus. Tetrahedron Lett 50 759-762... 

Schlick TL, Ding Z, Kovacs EW, Francis MB (2005) Dual-surface modification of the tobacco mosaic virus. J Am Chem Soc 127 3718-3723... 

Figure 5.4 Structure and manner of assembly of a simple virus, tobacco mosaic virus, (a) Electron micrograph at high resolution of a portion of the virus particle, (b) Assembly of the tobacco mosaic virion. The RNA assumes a helical configuration surrounded by the protein capsomeres. The center of the particle is hollow.

A typical virus with helical symmetry is the tobacco mosaic virus (TMV). This is an RNA virus in which the 2130 identical protein subunits (each 158 amino acids in length) are arranged in a helix. In TMV, the helix has 16 1/2 subunits per turn and the overall dimensions of the virus particle are 18 X 300 nm. The lengths of helical viruses are determined by the length of the nucleic acid, but the width of the helical virus particle is determined by the size and packing of the protein subunits. 

Ribonuclease (RNase) reconstruction The tobacco mosaic virus... 

Completely different mechanisms are involved in the self-assembly of the tobacco mosaic virus (TMV). This virus consists of single-strand RNA, which is surrounded by 2,130 identical protein units, each of which consists of 158 amino acid residues. A virus particle, which requires the tobacco plant as a host, has a rodlike structure with helical symmetry ( Stanley needles ). It is 300 nm long, with a diameter of 18nm. The protein and RNA fractions can be separated, and the viral... 

Nagata, T., Okabe, K., Takebe, I. and Matsui, C. (1981). Delivery of tobacco mosaic virus RNA into plant protoplasts mediated by reverse-phase evaporation vesicles (liposomes). Mol. Genet. Genomics 184, 161-5. 

Perham, R.N., and Thomas, J.O. (1971) Reaction of tobacco mosaic virus with a thiol-containing imi-doester and a possible application to X-ray diffraction analysis./. Mol. Biol. 62, 415—418. 

Antibody, murine IgG-2b/K, against tobacco mosaic virus Suspension Nicotiana tabacum (tobacco) A. tumefaciens transformation of leaf explant CaMV 35 S Murine 15 4g g 1 wet weight (i) 45 4g g 1 wet weight (i) with amino acids 62... 

Fig. 2.1 Root growth (O) and accumulation of tobacco mosaic virus (TMV) ( ) in hairy roots of N. benthamiana. TMV concentrations were measured by ELISA. The error bars indicate standard errors from four replicate shake-flask cultures.

Tobacco mosaic virus CP replacement, Second subgenomic promoter (sgp), CP fusion, Readthrough fusion with CP, fusion with cleavage site, fusion with CtxB malaria, rabies virus, M HV, FMDV, HCV, BHV-1, Ps. aeruginosa, neuropeptide, TMOF, allergens, MABs, a-trichosanthin, cytokines a-galactosidase-A, scFvs 11, 16,17, 52, 59-61... 

Pseudomonas aeruginosa membrane protein F Epitope display on tobacco mosaic virus in tobacco leaf Elicited specific antibodies against 7 immuno-type strains. Immunogenic in mice when delivered parenterally. Mice protected when challenged with model chronic pulmonary infection with P. aeruginosa. 20... 

Murine hepatitis virus Tobacco mosaic virus Mice developed serum IgG and IgA specific for Protective in mice immunized parenterally 105... 

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