Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Probing host-viral and viral-viral protein interactions in two plant viruses using a yeast two hybrid system
Abstract
Plant viruses encode only several proteins and require a compatible host to replicate. Thus, host-viral interactions are likely both specific and essential. Interactions among viral proteins are also likely to be important and allow efficient exploitation of their small genome. The goal of this research was to determine the suitability of a yeast two hybrid system to identify candidate plant proteins which interact with the proteins of brome mosaic virus (BMV) and to catalog protein-protein interactions among barley stripe mosaic virus (BSMV) gene products. Rice and barley cDNA libraries fused to the activation domain of GAL 4 were screened against BMV cDNA-DNA binding domain fusions. Eight and five rice genes interacted specifically with BMV movement protein and coat protein, respectively. Seven barley proteins interacted with BMV polymerase. The genes were sequenced and partially characterized. One group of proteins represented small, unknown peptides, with strong affinity towards their corresponding BMV partners. While these probably are irrelevant to the biology of BMV, they might be useful for development of anti-viral peptides. Another group consisted of known proteins, namely HSP70, ubiquitin, Tcomplex (TCP-theta subunit) from rice, and barley glyceraldehyde-3-phosphate dehydrogenase. The TCP subunit cDNA is the first ever cloned from plants. BMV protein domains responsible for each of these interactions were identified. Northern blot analyses showed slight differential expression of these genes in healthy and BMV-infected barley. These genes were expressed in Nicotiana benthamiana with a TMV-based vector. Unexpectedly, TMV inhibited BMV accumulation in N. benthamiana, but not in barley. This inhibition was prevented by coexpression of rice TCP. In BSMV, interactions between $\alpha$a-$\alpha$a (putative methyltransferase/helicase) and $\beta$a-$\beta$a (coat protein) were identified. The self-interaction of BSMV $\alpha$a is, after BMV, the second example of potential self-association of viral methyltransferase/helicases from alpha-like viruses and suggests that this is a common feature of these viral proteins which are essential for virus replication. The ability of BSMV coat protein to form multimers is likely a prerequisite for virus self-assembly.
Subject Area
Molecular biology
Recommended Citation
Ghosh, Aparajita, "Probing host-viral and viral-viral protein interactions in two plant viruses using a yeast two hybrid system" (1997). ETD collection for University of Nebraska-Lincoln. AAI9819696.
https://digitalcommons.unl.edu/dissertations/AAI9819696