The Functions Of OsSEC18and OsVPS37Genes In Rice

Rice is an important model crop for biological research. Protein transporting plays an important role through the whole life, protein transport pathway has an important role in seed protein accumulation and grain yield. Two important events of the protein transport pathway is vesicle fusion and degradation of ubiquitinated cargo proteins. Research of vesicle fusion and the cargo protein degradation mechanism has focused on yeast and mammalian cells, there are still many unknown areas in plant cells. In our study, we did some research about the function of OsSEC18gene and OsVPS37gene in rice, the two key genes in vesicle fusion and cargo protein degradation pathway. The main results are as follows:1. We found a290kDa complex of OsSecl8p in rice endosperm cells by Gel-filtration experiments, and found that this complex including Os60sP0p. The interaction between OsSecl8p and Os60sP0p could confirmed by yeast two-hybrid assay. Co-immunoprecipitation results showed that the OsSecl8p is interacted with free Os60sP0p in rice endosperm.2. Lack of sequence analysis confirmed that the OsSecl8p N-terminal amino acids1to260regional and C-terminal amino acids470to744area are interact with Os60sP0p, and the N-terminal1to128amino acid region of the Os60sP0p and C-terminal215to320amino acid region are interact with OsSecl8p.3. OsSEC18gene overexpression leads to a dwarf phenotype of plant height, and leaf cells smaller and more closely between cells. As Os60sP0p involved in the proliferation of human breast cancer and liver cancer cells, we speculate that the interaction between OsSecl8p and Os60sP0p may the molecular mechanism which cause the phenotype of OsSEC18gene overexpression lines's. Our results suggest that OsSEC18genes may relate to rice leaf cells proliferation.4. We use full-length cDNA of OsVPS37gene screens rice leaf cDNA library of bacterial two-hybrid and got the interacted protein of OsVps37p, glutamine synthetase enzyme OsGS1-1.5. We verify that OsVps37p can interact with OsGS1-1p in vitro by yeast two-hybrid systemt, analyzes the interaction region of these two proteins and found that the N-terminal amino acids1to76and C-terminal142to234amino acids region of OsVps37p can bind to OsGS1-1p and the N-terminal1to90amino acid region of GS1-1p interact with OsVps37p.6. Co-immunoprecipitation and Gel filtration experiments confirmed that OsVps37p and OsGS1-1p can interact with each other in vivo, and OsVps28p also involved in this interaction. Activity assay shows that the activity of enzymes in the GS-GOGAT pathway increased when expression the OsVPS37genes and OsVPS28gene in BY2cells.7. Transient expression of BY2cells shows that OsGS1-1p can affect the cellular localization of the ESCRT-I complex, suggesting that ESCRT-I complex play an important in the transport of OsGS1-1p.8. Based on the above results, OsVPS37genes involved in nitrogen recycling by interact with glutamine synthetase OsGS1-1p, and this provides a new mathord to increase the Nitrogen utilization.