Disease relevance of TMGMVgp2

• Mapping nucleotides in the 126-kDa protein gene that control the differential symptoms induced by two strains of tobacco mosaic virus [1].
• The relationship between systemic mosaic symptoms and the occurrence of viral 126-kDa protein in X-bodies was studied in tobacco infected with the tobacco mild green mosaic virus (TMGMV) strains U2, U5, and ribgrass mosaic virus (RMV) strain HR, and in other plant species infected with tobacco mosaic virus (TMV) strain W U 1 [2].
• Here, we report that Agrobacterium tumefaciens-mediated transient expression of short hairpin RNA (shRNA) could inhibit tobacco mosaic virus (TMV) RNA accumulation by targeting the gene encoding the replication-associated 126 kDa protein in intact plant tissue [3].

High impact information on TMGMVgp2

• 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) [4].
• The first class of artificially constructed dRNAs had the helicase and polymerase (POL) domains deleted; the second had an intact 126-kDa protein open reading frame (ORF) [4].
• The protein and not the nucleotide sequence directly controlled the symptom phenotype when amino acid 360 within the 126-kDa protein sequence was altered and likely controlled the symptom phenotype when amino acid 601 was altered [5].
• Based on these results and the known synergies between TMV and other viruses, the mechanism of suppression by the 126-kDa protein is compared with those utilized by other originally characterized suppressors of RNA silencing [6].
• However, fusion constructs encoding the first 781 amino acids or the entire 126-kDa ORF did not accumulate within the nucleus but instead associated with the endoplasmic reticulum (ER), forming spot-like inclusions [7].

Biological context of TMGMVgp2

• 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].
• The mutations were located in the middle of the 126-kDa protein (126 K) gene; one mutation influenced amino acid substitution at 649th Val to Ala (V649A), and the other was silent [9].
• During the development of systemic mosaic symptoms in tobacco mosaic virus (TMV)-infected tobacco, the viral non-structural 126-kDa-protein was present among the chromatin-associated proteins in fractionated leaf homogenates [Van Telgen HJ et al. (1984) Virology 143: 612-616] [10].

Associations of TMGMVgp2 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 TMGMVgp2

• Accumulation of the 126 kDa protein of tobacco mosaic virus during systemic infection analysed by immunocytochemistry and ELISA [12].
• Western blot analysis of both inoculated and noninoculated leaves revealed the presence of TMV-encoded 126-kDa protein and the absence of coat protein for both mutants [13].
• Using an antiserum raised against a fusion protein of beta-galactosidase and part of the 126-kDa-protein of TMV, this viral protein was detected by immunoelectron microscopy in X-bodies in infected tissue [10].

References