EXPRESSION OF DE-NOVO HIGH-LYSINE ALPHA-HELICAL COILED-COIL PROTEINS MAY SIGNIFICANTLY INCREASE THE ACCUMULATED LEVELS OF LYSINE IN MATURE SEEDS OF TRANSGENIC TOBACCO PLANTS

We have designed protein molecules based on an alpha-helical coiled-co il structure. These proteins can be tailored to complement nutritional ly unbalanced seed meals. In particular, these proteins may contain up to 43% mol/mol of the essential amino acid lysine. Genes encoding suc h proteins were constructed using synthetic oligonucleotides and the p rotein stability was tested for in vivo by expression in an Escherichi a coli model system. A protein containing 31% lysine and 20% methionin e (CP 3-5) was expressed in transgenic tobacco seeds utilizing the see d specific bean phaseolin and soybean beta-conglycinin promoters. Both promoters provided a level of expression in the mature transgenic tob acco seeds which resulted in a significant increase in the total lysin e content of the seeds. Several of these transgenic lines were analyze d for three generations to determine the stability of gene expression. Plants transformed with the soybean beta-conglycinin promoter/CP 3-5 gene consistently expressed the high-lysine phenotype through three ge nerations. However, expression of the high-lysine phenotype in plants transformed with the bean phaseolin/CP 3-5 was variable. This is the f irst report of a significant increase in seed lysine content due to th e seed-specific expression of a de novo protein sequence.