Disease relevance of TMGMVgp1

• Two classes of artificially constructed defective RNAs (dRNAs) of Tobacco mosaic virus (TMV) were examined in planta with helper viruses that expressed one (183 kDa) or both (126 and 183 kDa) of the replicase-associated proteins [1].
• Functions of the 126- and 183-kDa proteins of tobacco mosaic virus [2].
• However, transgenic plants containing essentially the same sequences, but with an additional insertion that would terminate translation in the middle of the 183-kDa gene, were highly resistant to systemic infection by TMV and other tobamoviruses [3].
• Computer analysis of the nucleotide sequence showed that CMV RNA 2 has a significant homology with RNA 2 of brome mosaic virus (BMV) and alfalfa mosaic virus (AMV) and also with a region for tobacco mosaic virus (TMV) RNA encoding the read-through part of the 183-kDa protein [4].

High impact information on TMGMVgp1

• The dRNAs with an intact 126-kDa protein ORF were replicated at moderate levels in protoplasts and in planta when supported by a TMV mutant that expressed the 183-kDa protein but not the 126-kDa protein (183F) [1].
• Elucidating the role(s) of 126/183-kDa proteins in movement is complicated because these proteins have multiple functions associated with replication and gene expression [5].
• Systemic symptoms induced on Nicotiana tabacum cv. Xanthi by Tobacco mosaic virus (TMV) are modulated by one or both amino-coterminal viral 126- and 183-kDa proteins: proteins involved in virus replication and cell-to-cell movement [6].
• Here we compare the systemic accumulation and gene silencing characteristics of TMV strains and mutants that express altered 126- and 183-kDa proteins and induce varying intensities of systemic symptoms on N. tabacum [6].
• Particles containing mutant forms of the viral RNA in which large sections of the 126-kDa and 183-kDa protein ORFs were missing were not disassembled in the 3'-to-5' direction when they were introduced into cells [7].

Biological context of TMGMVgp1

• Both the virus-encoded 126-kDa protein, which has amino-acid sequence motifs typical of methyltransferases and helicases, and the 183-kDa protein, which has additional motifs characteristic of RNA-dependent RNA polymerases, are required for efficient TMV RNA replication [8].
• A second TMV-derived RNA replicon, without any internally repeated sequences and containing a deletion of the 5' portion of the 30-kDa ORF as well as most of the 126/183-kDa ORF, was created and coinoculated with wild type TMV as helper [9].
• These changes resulted in 12 amino acid alterations in the open reading frames encoding the 126/183-kDa and 30-kDa movement proteins; two of these changes were determined not to be responsible for the attenuated phenotype [10].

Associations of TMGMVgp1 with chemical compounds

• We show that actinomycin D dramatically stimulates the synthesis of the 30-kDa protein by up to 2 orders of magnitude, whereas the synthesis of the viral 126 kDa, the 183 kDa, and the coat protein is increased only by a factor of 2 [11].

Analytical, diagnostic and therapeutic context of TMGMVgp1

• The ELISA assay developed enabled routine detection of viral 126 kDa (as well as 183 kDa) protein in samples of less than 5 mg of systemically infected leaves [12].

References