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At least 127 records · Page 7Linked to original sources
PubMed2000

Cell-to-cell movement of TMV RNA is temperature-dependent and corresponds to the association of movement protein with microtubules.

The movement protein (MP) of tobacco mosaic virus (TMV) is essential for spread of the viral RNA genome from cell to cell. During infection, the MP associates with microtubules, and it has been proposed that the cytoskeleton transports the viral ribonucleoprotein complex from ER sites of synthesis to plasmodesmata through which infection spreads into adjacent cells. However, microtubule association of MP was observed in cells undergoing late infection rather than in cells undergoing early infection at the leading edge of expanding infection sites where virus RNA cell-to-cell spread occurs. Therefore, alternative roles for microtubules in virus infection have been proposed, including a role in MP degradation. To further investigate the role of microtubules in virus pathogenesis, we tested the efficiency of cell-to-cell spread of infection and microtubule association of the MP in response to changes in temperature. We show that the subcellular distribution of MP is temperature-dependent and that a higher efficiency of intercellular transport of virus RNA at elevated temperatures corresponds to an increased association of MP with microtubules early in infection.

Green Fluorescent Proteins↗
PubMed2001

Local expression of enzymatically active class I beta-1, 3-glucanase enhances symptoms of TMV infection in tobacco.

Mutant tobacco plants deficient for class I beta-1,3-glucanase (GLU I) are decreased in their susceptibility to virus infection. This is correlated with delayed virus spread, a reduction in the size exclusion limit of plasmodesmata and increased cell-wall deposition of the beta-1,3-glucan callose. To further investigate a role of GLU I during cell-to-cell movement of virus infection, we inserted the GLU I coding sequence into TMV for overexpression in infected cells. Compared with the size of local lesions produced on plants infected with virus expressing either an enzymatically inactive GLU I or a frameshift mutant of the gene, the size of local lesions caused by infection with virus expressing active GLU I was consistently increased. Viruses expressing antisense GLU I constructs led to lesions of decreased size. Similar effects were obtained for virus spread using plants grown at 32 degrees C to block the hypersensitive response. Together, these results indicate that enzymatically active GLU I expressed in cells containing replicating virus can increase cell-to-cell movement of virus. This supports the view that GLU I induced locally during infection helps to promote cell-to-cell movement of virus by hydrolyzing callose. Moreover, our results provide the first direct evidence that a biological function of a plant beta-1,3-glucanase depends on its catalytic activity.

Biological Transport↗
PubMed1987

Cooperative thermal denaturation of the assembly origin region of TMV RNA.

The assembly origin (AO) region of the tobacco mosaic virus RNA melts in an usually narrow (2.5 degrees C) temperature range. In an 0.01 M phosphate buffer the melting temperature of AO was found to be 41.5 degrees C. This value corresponds to the regions with the most stable secondary/tertiary structure of the whole TMV RNA molecule. It is assumed that the AO region has a specific tertiary structure, which is maintained by the long-range interactions as well as by interactions of the pseudoknot type.

Base Sequence↗
PubMed1983

Molecular cloning and nucleotide sequence of the 30K and the coat protein cistron of TMV (tomato strain) genome.

The cDNA copies of tobacco mosaic virus (TMV)-tomato strain (L) genome were cloned by the method of Okayama and Berg (Mol. Cell. Biol. 2, 161-170. (1982)) and the sequence of 1,614 nucleotides at the 3' end was determined. The sequence encompasses the 30K and the coat protein cistron which are located in residues 685-1, 479 and 203-682 from the 3' end of the genome respectively. The close relationship between the tomato and the common strain was shown on the level of the nucleotide sequence. Highly homologous regions are found in the 3' non-coding region, the assembly origin and the 5' flanking region of the 30K protein cistron. The comparison of the deduced amino acid sequence between the tomato and the common strain shows that the 30K protein is composed of the conserved N-terminal four-fifth and the highly divergent region near the C-terminus.

Amino Acid Sequence↗
PubMed1995

Assessment of the mutagenicity of extracts of TMV-coat-protein-gene induced transgenic tomato by the umu-test.

We examined the mutagenicity of extracts (juice and ethanol extract) from a transgenic tomato that was established by transfection of a gene encoding the coat protein of tobacco mosaic virus (TMV) to the F1 hybrid between Lycopersicon esculentum LA1000 and L. peruvianum PI128650, by the umu-test with Salmonella typhimurium TA1535/pSK1002 as the test organism. The extracts showed no detectable mutagenicity. The extracts from the above-mentioned F1 hybrids and wild tomatoes and cultivars (L. peruvianum PI128650, L. peruvianum PI126944, L. pimpinellifolium LS1524, L. pimpinellifolium LA722, L. hirsutum LS503, Mini-carol, Sun-cherry, Momotaro, Odoriko, Kagome77, and Ponderosa) also showed no detectable mutagenicity.

Capsid↗
PubMed2004

A TMV-Cg mutant with a truncated coat protein induces cell death resembling the hypersensitive response in Arabidopsis.

Tobacco mosaic virus (TMV)-Cg is able to propagate and multiply systemically to high levels in Arabidopsis thaliana ecotype Col-0. In this study, we obtained a Cg mutant, Cgk1, which expresses a coat protein with a truncated carboxyl terminus. Interestingly, Cgk1 induced necrosis that resembled the hypersensitive response and caused more pronounced disease symptoms than wild type Cg in Arabidopsis Col-0 plants. A reactive oxidative burst occurred prior to this necrosis. We found that expression of the pathogenesis-related gene PR-1 was induced by Cgk1 infection, and also by infection with wild type Cg, but only in npr1-2 mutant plants, not in NahG transgenic plants. These results suggested that PR-1 expression is dependent on the salicylic acid signaling pathway, but is independent of NPR1.

Amino Acid Sequence↗
PubMed1979

[Membrane proteins of chloroplasts of intact and TMV-infected tobacco plants].

The effects of viral infection on the membrane proteins from tobacco plant chloroplasts differing in their stability for TMV infection were studied. It was shown that the changes in the chloroplasts of labile and resistant tobacco varieties are oppositely directed. The data from amino-acid analysis, SH-group determination and infrared spectra of the membrane proteins of the resistant variety are indicative of conformational changes caused by disruption of the hydrogen bonds, which stabilize the protein, by changes in aggregability, etc. due to infection and metabolic disturbances in the infected cell. The conformational changes in the chloroplasts of the stable variety are adaptive and affect the biological activity, enzymatic and immunological properties and energy metabolism of the chloroplasts.

Amino Acids↗
PubMed1983

Point mutation in the 30-K open reading frame of TMV implicated in temperature-sensitive assembly and local lesion spreading of mutant Ni 2519.

Tobacco mosaic virus mutant Ni 2519 forms local lesions on tobacco cultivars carrying the N gene which, unlike wild-type lesions, do not enlarge at elevated temperature. This may reflect temperature sensitivity of a viral gene product required for cell to cell spreading of infectivity. Ni 2519 also carries an unselected cis-dominant lesion in viral assembly. Peptide mapping of in vitro translation products of Ni 2519 RNA reveals at least one, and possibly two changes in p30 and p19, two products of the 30-K open reading frame, compared with its parental strain A14. An A to G transition at position 5332 in Ni 2519 RNA accounts for the altered mobility of the major variable peptide. The corresponding A14 peptide itself differs from the wild-type due to another A to G transition at residue 5329. These residues are close to the viral assembly origin. A revertant virus population which could assemble at the restrictive temperature regained the wild-type sequence in place of the point mutation specific to Ni 2519 at position 5332, and formed wild-type local lesions as efficiently as the parental strain. This result implicates mutation of residue 5332 in the temperature sensitivity of viral assembly (by altering the structure of the RNA close to the assembly origin) and/or local lesion spreading (via a radical Arg to Gly substitution in p30 or its derivatives). The mutation occurs in a position where the predicted amino acid sequence shows homology with a group of proteins encoded by yeast mitochondrial introns.

Journal Article↗