Virus satellite tobacco mosaic

The satellite ssRNA viruses are a group of ssRNA icosahedral viruses, which are the satellites to certain plant viruses (Pritsch and Mayo, 1989). Satellite tobacco necrosis virus (STNV), a satellite virus to tobacco necrosis virus, was in fact one of the first icosahedral virus structures to be determined by X-ray crystallography (Liljas et al, 1982). In more recent years, two other satellite plant viruses, satellite tobacco mosaic virus (STMV) (Larson et al, 1993, 1998) and satellite panicum mosaic virus (SPMV) (Ban and McPherson, 1995), have been determined. These are perhaps the simplest and smallest icosahedral viruses whose structures have been determined by X-ray crystallography. Of relevance to our discussion is the structure of STMV determined to 1.8-A resolution, which shows extraordinary details about genome organization (Larson et al, 1998 Larson and McPherson, 2001). 

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... 

Satellite viruses are those that are dependent for their own replication on some (catalytic) activity encoded in another helper virus that coinfects the host cell. The structures of three plant ssRNA satellite viruses represent some of the highest resolutions known and have been comparatively reviewed (Ban et al., 1995). The structures of satellite tobacco mosaic virus (STMV) (Larson et al., 1993a,b), satellite tobacco necrosis virus (STNV) (Jones and LUjas, 1984 Liljas et al., 1982), and satellite panicum mosaic virus (SPMV) (Ban and McPherson, 1995) have T=1 capsids composed of 60 identical copies of unembellished jelly-roll j3 barrels constructed of only 155 to 195 amino acids (Fig. la see Color Insert). What is remarkable is how little the assembly context of these domains is conserved. The same end always points toward the 5-fold axis, but the domains are rotated to different extents around the 5-fold axis. Furthermore, between STNV and the others, there is a 70° rotation of the barrel about its long axis. Contacts across the dimer interface are... 

Larson, S. B., and McPherson, A. (2001). Satellite tobacco mosaic virus RNA Stmcture and implications for assembly. Curr. Opin. Struct. Biol. 11, 59-65. 

Satellite tobacco mosaic vims (STMV), 153, 222-225 encapsidated genome of, 223 Satellite tobacco necrosis vims (STNV), neutron scattering and, 49-50, 222 Satellite viruses, viral stmcture taxonomy and, 139-141, 139... 

FIGURE 3.1 Crystals of a variety of macromolecules. In (a), clusters of needle crystals of bacterial a amylase in (b), crystals of a protease from pineapple, in (c), a crystal of satellite tobacco mosaic virus and in (d), a crystal of the sweet protein thaumatin. 

Freddolino, P.L., Arkhipov, A.S., Larson, S.B., Mcpherson, A., Schul-ten, K. Molecular dynamics simulations of the complete satellite tobacco mosaic virus. Structure 2006,14, 437-49. 

Fig. 2. The YPMa trimer shown with trimeric structures of virus capsid proteins and members of the TNF superfamily highlights the diversity of trimerization of jelly roll folds. Only C atoms of the polypeptide chains are shown. Virus trimers were extracted from the Viper database of virus structures (http //viperdb.scripps.edu/) [64], SPMV = Satellite pan-icum mosaic virus STMV = satellite tobacco mosaic virus. Figures 1 and 2 were created using Swiss-PdbViewer [65],... 

Figure 10 Linear proportionality between the genome length and the net positive charge on all polypeptide tails in a capsid/ The generality of the result is borne out in many viruses, including satellite tobacco mosaic, hepatitis B, Flock house, and Sindbis viruses. The pictures of the vimses are from http // www.ICTVdb.org/...

Figure 2. Examples of multiple pseudoknots predicted in the plant viral RNAs of (a) tobacco mosaic virus (39) and (b) satellite tobacco mosaic virus (52).

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. 

Most of the EF-hand motifs have one water (—X). On the other hand, in Rhizopus chinensis aspartic proteinase (Suguna et al., 1987) there is one main-chain carbonyl oxygen bound to calcium and six water molecules to complete the pentagonal bipyramidal coordination. Calcium coordination has been measured in several viruses, such as Southern bean mosaic virus (Silva and Rossmann, 1985), satellite tobacco necrosis virus (Jones and Liljas, 1984), and tomato bushy stunt virus IV (Olson et al., 1983). 

Several plant viruses have been studied using X-ray crystallography and conventional X-ray sources. These are, in no particular order, TBSV (tomato bushy stunt virus), SBMV (southern bean mosaic virus) and STN V (satellite tobacco necrosis virus) - all spherical viruses - and TMV (tobacco mosaic virus) - a cylindrical virus. These virus crystals diffract relatively well and are reasonably stable to radiation. 

Viruses (purified) Asymmetrical Separation of five aggregates of the Satellite tobacco necrosis virus isolation of the Cow pea mosaic vims. ... 

These experiments have been dissapointing in the sense that the only features which seem to be universal are the AUG initiation codon and the 5 cap structure (7I, 72), and even the latter is missing from some viral RNAs, notably picornavirus RNAs (both the virion RNA (75) and. the viral mRNA (74)), Cowpea Mosaic Virus (CPMV) RNA (75)f and Satellite Tobacco Necrosis (STNV) RNA (76). The role of the cap has been studied by examining the properties of mRNA... 

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