Improving protein content and quality by over-expressing artificially synthetic fusion proteins with high lysine and threonine constituent in rice plants

• DOI: 10.1038/srep34427
• Publication Date: 2016-09-28T09:32:13Z
• Authors: Shu-Ye Jiang; Ali Ma; Lifen Xie; Srinivasan Ramach...
• Keywords: 2. Zero hunger; 0301 basic medicine; 0303 health sciences; 03 medical and health sciences; Article

AbstractRice grains are rich in starch but low in protein with very low level of both lysine and threonine. Thus, it is important to further improve protein quality and quantity, especially to increase lysine and threonine content in rice grains. We artificially synthesized two new genes by fusing endogenous rice genes with lysine (K)/threonine (T) motif (TKTKK) coding sequences. They were designated asTKTKK1andTKTKK2and their encoded proteins consist of 73.1% and 83.5% of lysine/threonine, respectively. These two genes were under the control of 35S promoter and were independently introduced into the rice genome to generate transgenic plants. Our data showed that overexpression ofTKTKK1generated stable proteins with expected molecular weight and the transgenic rice seeds significantly increased lysine, threonine, total amino acids and crude protein content by 33.87%, 21.21%, 19.43% and 20.45%, respectively when compared with wild type control; significant improvement was also observed in transgenic rice seeds overexpressingTKTKK2. However, limited improvement in protein quality and quantity was observed in transgenic seeds carrying tandom array of these two new genes. Our data provide the basis and alternative strategy on further improving protein quality and quantity in other crops or vegetable plants by synthetic biology.