Tobacco mosaic virus self assembly

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... 

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-... 

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. 

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... 

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

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. 

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). 

Percolation is widely observed in chemical systems. It is a process that can describe how small, branched molecules react to form polymers, ultimately leading to an extensive network connected by chemical bonds. Other applications of percolation theory include conductivity, diffusivity, and the critical behavior of sols and gels. In biological systems, the role of the connectivity of different elements is of great importance. Examples include self-assembly of tobacco mosaic virus, actin filaments, and flagella, lymphocyte patch and cap formation, precipitation and agglutination phenomena, and immune system function. 

Miller RA, Presley A, Francis MB. Self-assembling light-harvesting systems from synthetically modified tobacco mosaic virus coat proteins. J Am Chem Soc 2007 129 3104-9. 

Certain viruses, notably tobacco mosaic virus (TMV), can also self-assemble. A TMV particle can be dissociated into its component proteins and RNA and then reassembled into infective virus particles on mixing the components together again. 

Many other examples of outwardly complex molecular structures, whose salient architectural features appear to self-assemble from their constituent building blocks, have been documented [16]. The formation of the DNA double helix from its constituent chains is perhaps the quintessential example, whilst the perfect reconstitution of the intact tobacco mosaic virus from its constituent RNA and protein monomers also exhibits all the hallmarks of a cooperative self-assembly process [17]. The same is true of ribonuclease. Reconstitution of this enzyme in the presence of mercaptoethanol, to allow reversible exchange of the four disulfide bridges, proceeds smoothly to generate eventually only the active conformation from many possible isomeric states [18], In each of these cases, the thermodynamic stability of the product is vital in directing its synthesis. These syntheses could therefore be termed product-directed. 

Caspar, D. L., and Namba, K. (1990). Sivitching in the self-assembly of tobacco mosaic virus. Adv. Biophys. 26, 157-185. 

C as proven by SANS. This stepwise growth of the columns shows great similarity to the self-assembly of the tobacco mosaic virus without the ribonucleic acid strand and will undoubtedly aid in the understanding of bio polymer self-assembly.238... 

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