Accurate aminoacylation of tRNAs depends upon the integrity of the tRNA anticodon and a balance of tRNA and aminoacyl tRNA synthetase. Changes in either reduce the fidelity of protein synthesis and promote recoding of proteins, so as to alter their structures and functions. Heritable expression of altered tRNAlys in rice (Oryza sativa L.) results in recoding and enrichment of lysine in seed storage proteins, without changing their type or relative amounts (1). Under field conditions, progeny plants of these transgenic rice lines maintained normal grain weight and appearance, elevated lysine and protein levels, but exhibited decreased spikelet fertility and early cessation of grain elongation and filling, resulting in lower yields. Plants expressing both altered tRNAs and a lysine-insensitive dihydropicolinate synthase (DHPS) exhibited additional recoding of seed storage proteins, and might suggest a strategy for targeting recoding to the endosperm. Complementary approaches in maize (Zea mays L.) expressing elevated lysyl tRNA synthetase also cause translational recoding of lysine into zeins, significantly enriching the lysine content of grain (2).

Reference: 1. Wu XR, Chen, ZH and Folk, WR (2003) Plant Biotechnol. J. 1,187-194 2. Wu, XR, Kenzior A, Wilmot D, Scanlon S, Chen ZH, Topin A, He S, Acevedo A and & Folk, WR (2007) Plant J. doi:10.1111/j.1365-313X.2007.03076.x