|Jang, Chan Young|
|Kim, Hong Gi|
Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2011
Publication Date: 2/1/2012
Citation: Lim, H., Jang, C., Nam, J., Li, M., Hong, J., Bae, H., Ju, H., Kim, H., Ford, R., Domier, L.L. 2012. Characterization of the in vitro activities of the P1 and helper component proteases of Soybean mosaic virus Strain G2 and Tobacco vein mottling virus. Plant Pathology. 28:197-201. Interpretive Summary: Infection of soybean plants by viruses like Soybean mosaic virus (SMV) can result in significant reduction in the amount and quality of seeds harvested. During infection, SMV utilizes protease enzymes to produce proteins that are required for infection. For some human virus diseases, compounds that inhibit the activity of viral proteases have been effective in reducing the severity of virus infections. Soybean plants produce large amounts of protease inhibitors during seed development and in response to wounding that could affect the activities of these proteases. In this study, activities of two of the proteases of SMV and Tobacco vein mottling virus (TVMV), a tobacco-infecting virus, were compared to test the hypothesis that SMV protease enzymes are less susceptible to the effects of selected proteinase inhibitors than those of the tobacco-infecting virus. The experiments showed that the proteases produced by SMV, a virus that is transmitted through soybean seed, were less sensitive to selected protease inhibitors produced by rabbits and by soybean than were the proteases of TVMV, which is not transmitted through seed of tobacco plants. The results suggest that it may be possible to use protease inhibitors to provide resistance to viruses in plants through the careful evaluation and selection of highly effective protease inhibitors. This work will be of interest to scientists who are interested in developing broad-spectrum antiviral control strategies for plants.
Technical Abstract: Potyviruses express their RNA genomes through the production of polyproteins that are processed in host cells by three virus-encoded proteases. Soybean plants produce large amounts of protease inhibitors during seed development and in response to wounding that could affect the activities of these proteases. The in vitro activities of two of the proteases of Soybean mosaic virus (SMV) and Tobacco vein mottling virus (TVMV) were compared in the rabbit reticulocyte lysate in vitro translation system using synthetic RNA transcripts. Transcripts produced from SMV and TVMV cDNAs that included the P1 and helper component-protease (HCPro) coding regions directed synthesis of protein products that were only partially processed. Unprocessed polyproteins were not detected from transcripts that included all of the P1, HC-Pro, P3 and portions of the cylindrical inclusion protein coding regions of either virus. Addition of soybean trypsin inhibitor to in vitro translation reactions increased the accumulation of the unprocessed polyprotein from TVMV transcripts, but did not alter the patterns of proteins produced from SMV. These experiments suggest that SMV- and TVMV-encoded proteases are differentially sensitive to protease inhibitors.