Tobacco mosaic virus , assembly

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.

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... 

Many protein molecules are composed of more than one subunit, where each subunit is a separate polypeptide chain and can form a stable folded structure by itself. The amino acid sequences can either be identical for each subunit (as in tobacco mosaic virus protein), or similar (as in the a and )3 chains of hemoglobin), or completely different (as in aspartate transcarbamylase). The assembly of many identical subunits provides a very efficient way of constructing... 

Subunit motion between two positions is also critical to the assembly of tobacco mosaic virus. In the partially assembled disks, having two stacked layers of 17 subunits each, the layers are wedged apart toward their inner radius. During assembly of the viral helix, RNA binds between the layers, which then clamp tightly together with 164 subunits per turn (Bloomer et al., 1978 Butler and Klug, 1978). 

Assembly and Stability of the Tobacco Mosaic Virus Particle D. L. D. Caspar... 

True self-assembly is observed in the formation of many oligomeric proteins. Indeed, Friedman and Beychok reviewed efforts to define the subunit assembly and reconstitution pathways in multisubunit proteins, and all of the several dozen examples cited in their review represent true self-assembly. Polymeric species are also formed by true self-assembly, and the G-actin to F-actin transition is an excellent example. By contrast, there are strong indications that ribosomal RNA species play a central role in specifying the pathway to and the structure of ribosome particles. And it is interesting to note that the assembly of the tobacco mosaic virus (TMV) appears to be a two-step hybrid mechanism the coat protein subunits first combine to form 34-subunit disks by true self-assembly from monomeric and trimeric com-... 

Any polymerization reaction in which the product of each elongation step can itself also undergo further polymerization. When the same types of bonds and/or conformational states that are present in the reactant(s) are generated within product(s) during elongation, the process is referred to as isodesmic polymerization. Such is the case for the indefinite polymerization of actin, tubulin, hemoglobin S, and tobacco mosaic virus coat protein. See Nudeation Protein Polymerization Actin Assembly Kinetics Microtubule Assembly Kinetics Microtubule Assembly Kinetics... 

Another complex macromolecular aggregate that can reassemble from its components is the bacterial ribosome. These ribosomes are composed of 55 different proteins and by 3 different RNA molecules, and if the individual components are incubated under appropriate conditions in a test tube, they spontaneously form the original structure (Alberts et al., 1989). It is also known that even certain viruses, e.g., tobacco mosaic virus, can reassemble from the components this virus consists of a single RNA molecule contained in a protein coat composed by an array of identical protein subunits. Infective virus particles can self-assemble in a test tube from the purified components. 

The association of amphiphiles is strongly solvent-, temperature-, pH- and concentration-dependent. The studies of various aggregates formed by a cholesterol derivative 91 [31 ] illustrate this point (Figure 4.11). The dissociation and reassembling of tobacco mosaic virus into its constituent parts discussed in Section 5.2.1 provides an elegant example of a more complicated assembly... 

Let us consider the structure of the tobacco mosaic virus first. As shown schematically in Figure 5.1, it is composed of a single strand of ribonucleic acid, RNA, covered by a sheath formed from 2130 identical protein units. Thus the whole virus constitutes a rather simple supramolecular assembly. By changing... 

The process of assembling of tobacco mosaic virus exhibits several characteristic features ensuring its effectiveness [7] ... 

Sixty copies of the latter are assembled around the RNA in an icosahedral array (Fig. 7-14) to form the virion. The structure of the similar satellite tobacco mosaic virus has also been described in detail.486 487... 

Keywords wrinkling Thin-film Elastomeric polymer Polydimethylsiloxane Patterns Deformation Surfaces Self-assembly Polyelectrolyte multilayer films Thin-films Polymer brushes Colloidal crystallization Mechanical-properties Assembled monolayers Buckling instability Elastomeric polymer Tobacco-mosaic-virus Soft lithography Arrays... 

Wargacki SP, Pate B, Vaia RA (2008) Fabrication of 2D ordered films of tobacco mosaic virus (TMV) processing morphology correlations for convective assembly. Langmuir 24 5439-5444... 

Strict Self-Assembly The Tobacco Mosaic Virus and DNA... 

S-TT Klug, A., The tobacco mosaic virus particle structure and assembly , Phil. Trans. RoyalSoc. Ser. B, Biol. Scl. 1999, 354, 531-535. 

We have already dealt with some general aspects of biochemical self-assembly in Section 2.10 including the remarkable formation of viral capsids. There are some biochemical examples, however, that translate readily into supramolecular chemical concepts and have been pivotal in defining the field. One such system is the tobacco mosaic virus, a virus that is very harmful to a variety of crops including tobacco, tomato, pepper, cucumbers and species such as ornamental flowers. This system consists of a helical virus particle measuring some 300 X 18 nm (Figure 10.6). A central strand of RNA is sheathed by 2130 identical protein subunits, each of which contains 158 amino acids. What is remarkable about... 

Figure 10.7 (a)-(d) Stepwise self-assembly of the tobacco mosaic virus. (Copyright Wiley-VCH... 

Self-assembly is of considerable importance in biochemistry where it helps us understand the structure of DNA and of viruses such as the tobacco mosaic virus. 

Figure 12 Diagram of assembled states of the coat protein of tobacco mosaic virus M free monomers, BD cylindrical disks, LW/H protohelices and helices. Symbols results from differential scanning microscopy DSC, titration, and sedimentation experiments, lines theory. The theory is based on binding energy Equation (9) and presumes competing repulsive Coulomb and attractive hydrophobic interactions (Kegel and van der Schoot, 2006).

Butler, P.J.G. "Self-assembly of tobacco mosaic virus the role of an intermediate aggregatein generating both specicity and speed". Philos. Trans. R. Soc. Lond. B Biol. Sci. 354, 537-550 (1999). 

Hiragi, Y., Inoue, H., Sano, Y., Kajiwara, K., Ueki, T., and Nakatani, H. "Dynanic mechanism of the self-assembly process of tobacco mosaic virus studied by rapid temperature-jump small-angle x-ray scattering using synchrotron radiation", f. Mol. Biol. 213,495-502 (1990). 

Kegel, W.K., and van der Schoot, P. "Physical regulation of the self-assembly of tobacco mosaic virus coat protein". Biophys. ]. 91,1501-1512 (2006). 

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