Tobacco mosaic virus coat protein

Figure 3.2 shows the fluorescence and phosphorescence emission spectrum from tobacco mosaic virus coat protein. These spectra are fairly typical of the tryptophan emission spectra observed from proteins at room temperature. 

Differences between the spectra of fluorescence and phosphorescence are immediately obvious. For all tryptophans in proteins the phosphorescence spectrum, even at room temperature, is structured, while the fluorescence emission is not. (Even at low temperatures the fluorescence emission spectrum is usually not structured. The notable exceptions include a-amylase and aldolase, 26 protease, azurin 27,28 and ribonuclease 7, staphylococcal endonuclease, elastase, tobacco mosaic virus coat protein, and Drosophila alcohol dehydrogenase 12. )... 

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... 

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). 

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. 

Chapman and Liljas, Fig. 5. The four-helix bundle, (a) The prototypical conformation of myohemerythrin (Sheriff et al, 1987) (b) the tobacco mosaic virus coat protein (Namba et al, 1989). 

Berger and Vanderkooi(88) studied the depolarization of tryptophan from tobacco mosaic virus. The major subunit of the coat protein contains three tryptophans. The phosphorescence decay is non-single-exponential. At 22°C the lifetime of the long component decays with a time constant of 22 ms, and at 3°C the lifetime is 61 ms. The anisotropy decay is clearly not singleexponential and was consistent with the known geometry of the virus. 

Viral coat proteins, see Southern bean mosaic virus, Tobacco mosaic virus, or Tomato bushy stunt virus... 

Redox Fe-S proteins High-potential iron protein Ferredoxin Viral coat proteins f Tomato bushy stunt virus protein I Southern bean mosaic virus protein Tobacco mosaic virus protein... 

The tobacco mosaic virus (center right), a plant pathogen, has a structure similar to that of MB, but contains ssRNA instead of DNA. The poliovirus, which causes poliomyelitis, is also an RNA virus. In the influenza virus, the pathogen that causes viral flu, the nucleocapsid is additionally surrounded by a coat derived from the plasma membrane of the host cell (C). The coat carries viral proteins that are involved in the infection process. 

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. 

One of the best understood of the many viral pathogens of plants is the tobacco mosaic virus (Fig. 7-8). Its 6.7-kb positive strand RNA encodes a replicase, coat protein, and at least one other protein.696... 

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).

Both X-ray and neutron fiber diffraction (as well as electron microscopy) techniques have been applied to filamentous viruses, for which the prospect of three-dimensional crystals is poor. By combining neutron and X-ray fiber diffraction, NMR, circular dichroism, and Raman and infrared spectroscopies, an atomic model for the filamentous bacteriophage Pfl has been derived (Liu and Day, 1994). Other studies concerning Pfl have relied on purely X-ray fiber diffraction data, together with molecular modeling, to provide detailed filament structures (Pederson et at, 2001 Welsh et at, 1998a,b, 2000). Eiber diffraction was also used to solve the structure of the rodlike helical tobacco mosaic virus (TMV), where all of the coat protein and three genomic nucleotides... 

The four-helix bundle is a common motif in which (usually) antiparallel a helices are packed side by side. It is found in myohemerythrin, various cytochromes, and a number of other proteins. A viral example is the coat protein of tobacco mosaic virus (TMV) (Bloomer et al, 1978). TMV represents the most common type, in which the helix axes are nearly antiparallel, off by 18°, coiled with a left-handed superhelical twist (Fig. 5 see Color Insert). The slight misalignment of the individual helix axes allows the side chains to interdigitate efficiently, burying internal hydrophobic side chains. 

Genes in all cellular organisms are made of DNA. The same is true for some viruses, but for others the genetic material is RNA. Viruses are genetic elements enclosed in protein coats that can move from one cell to another but are not capable of independent growth. One well-studied example of an RNA virus is the tobacco mosaic virus, which infects the leaves of tobacco plants. This virus consists of a single strand of RNA (6930 nucleotides) surrounded by a protein coat of 2130 identical subunits. An RNA-directed RNA polymerase catalyzes the replication of this viral RNA. 

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