| lant 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... |
