Enrichment of cereal protein lysine content by altered tRNA^lys coding during protein synthesis

Abstract

SummaryThe world's major crops are deficient in lysine and several other amino acids essential for human and animal nutrition. Increasing the content of these amino acids in cereals, our major source of dietary energy, can help feed a global population whose reliance upon dietary protein is growing faster than crop yields. Here we document the heritable expression in rice, the world's major cereal crop, of tRNA lys species that introduce lysine at alternative codons during protein synthesis, resulting in a significant enrichment of the lysine content of proteins in rice seeds without changing the types or quantities of the seed storage proteins.

Improving the Content of Essential Amino Acids in Crop Plants: Goals and Opportunities

“…Recently, another interesting approach has been adapted to increase the Lys content in cereal seeds, utilizing a recombinant tRNA(lys) species that introduces Lys at alternative codons during protein synthesis (Wu et al, 2003). Expression of a recombinant gene encoding this tRNA in transgenic rice (Oryza sativa) caused a meaningful enrichment of the Lys content of seed proteins (Wu et al, 2003).…”

“…Expression of a recombinant gene encoding this tRNA in transgenic rice (Oryza sativa) caused a meaningful enrichment of the Lys content of seed proteins (Wu et al, 2003). Notably, even stable expression of a wild-type Arabidopsis gene encoding a Lys tRNA synthetase in transgenic maize caused translational recoding of Lys into the Lys-deficient zein storage proteins, apparently using non-Lys codons, and resulted in significantly enriching the Lys content in the grain (Wu et al, 2007).…”

Cloning and Characterization of the DHDPS Gene Encoding the Lysine Biosynthetic Enzyme Dihydrodipocolinate Synthase from Zizania latifolia (Griseb)

“…Analysis of nutritional composition indicates that lysine content per 100 g seed in Z. latifolia (Griseb) is higher than that in rice; the former is 0.62±0.07 g and the latter is 0.26±0.02 g (Zhai et al 2000). Attempts have been made to improve the quality of rice by means of genetic engineering (Lee Soo and YenHe 2001;Wu et al 2003); however, engineering rice that meets the requirements of human nutrition still has not been developed. In addition, little research has been done on the valuable gene resources in Z. latifolia, including elucidating the mechanism of the high level lysine.…”

Biofortification of essential nutritional compounds and trace elements in rice and cassava

“…It is possible that the equilibrium of the amino acids also has to be adapted, e.g. with codon-modified tRNA (Wu et al 2003), which has been demonstrated to increase lysine content in cereals. …”