Evidence that the 37 kDa protein of Soil-borne wheat mosaic virus is a virus movement protein

Abstract

Experiments were conducted to determine if the 37 kDa protein (37K) of Soil-borne wheat mosaic virus (SBWMV) is a virus movement protein. First, evidence was obtained that indicated that 37K has the ability to move from cell to cell, similar to other virus movement proteins (MPs). Plasmids containing the GFP gene fused to the SBWMV 37K, the coat protein (CP) or the CP readthrough domain (RT) ORFs were delivered by biolistic bombardment to wheat and tobacco leaves. In wheat leaves, cell-to-cell movement of GFP-37K was observed, while GFP, GFP-CP and GFP-RT accumulated primarily in single cells. All fusion proteins accumulated in single cells in tobacco leaves. Thus, cell-to-cell movement is a specific property of 37K that occurs in SBWMV host plants. Subcellular accumulation of 37K was studied using SBWMV-infected and 37K-expressing transgenic wheat. In infected and transgenic wheat leaves, 37K accumulated in the cell wall, similar to other virus MPs, and in aggregates in the cytoplasm. Phylogenetic studies were conducted to compare the furovirus 37K proteins with members of the 30K superfamily of virus MPs. Amino acid sequences of the furovirus 37K proteins were aligned with the MPs from 43 representative viruses. The furovirus 37K proteins were found to reside in a clade that also contained the dianthovirus MPs. Combined, these data suggest that SBWMV 37K is probably a virus MP.

Identification of a Movement Protein of the Tenuivirus Rice Stripe Virus

“…The pattern of NSvc4 accumulation is similar to that observed previously for TMV and Cucumber mosaic virus MPs and for the Soilborne wheat mosaic virus 37K protein (1,12,13,29,40). Our observation of NSvc4 in cell walls though immunocytochemistry suggests that RSV NSvc4 may interact with the cytoskeleton and/or ER network in RSV-infected rice cells and travel along the network from viral replication sites to PDs in walls.…”

Estimation of the Size of Genetic Bottlenecks in Cell-to-Cell Movement of Soil- Borne Wheat Mosaic Virus and the Possible Role of the Bottlenecks in Speeding Up Selection of Variations in trans -Acting Genes or Elements

“…Soil-borne wheat mosaic virus (SBWMV), a positive-strand plant RNA virus, has a bipartite genome consisting of two RNA molecules, RNA1 and RNA2 (27,28). RNA1 encodes replication proteins and a movement protein (MP) for cell-to-cell movement (2). RNA2 encodes the capsid protein (CP) and two CP-containing proteins: CP-RT, produced by readthrough of a stop codon, and N-CP, initiated from an upstream CUG codon (25).…”

“…Then, substituting 0.5 for r 0 , we simultaneously estimated 0 , 1 , and 2 by maximizing the total log likelihood logL ϭ logL 0 ϩ logL 1 ϩ logL 2 Calculation was done using statistical computing software R (22), and we obtained the mean bottleneck sizes 0 ϭ 5.59 Ϯ 0.40, 1 ϭ 5.97 Ϯ 0.22, and 2 ϭ 5.02 Ϯ 0.29 (maximum likelihood estimates Ϯ standard errors).…”

Identification of a Movement Protein of Rice Yellow Stunt Rhabdovirus

“…The 30K superfamily of viral movement proteins has been demonstrated to have a variety of activities, including the ability to bind nucleic acids, to move to neighboring cells after microinjection or biolistic bombardment, to facilitate movement of RNA to neighboring cells, and to form tubular structures. Although the 30K MPs have similar functions, they exhibit very limited conservation of amino acid sequence (2,25). Instead, it has been suggested that a common three-dimensional structure built of a series of similarly organized secondary structure elements forms the basis for recognition of the putative 30K superfamily members (25).…”