The Molecular Biology of Amino Acid Biosynthesis in Plants

Abstract

All living organisms have a fundamental requirement for nitrogen as a component of amino acids, proteins and nucleic acids. It is not surprising, therefore, that there are broad similarities in nitrogen metabolism in plants, animals and microorganisms, and that many enzymes involved in the biochemistry of nitrogen metabolism are shared by all groups of organisms. Indeed several of the plant genes which encode enzymes involved in nitrogen metabolism have been cloned by virtue of their sequence homology to their counterparts in microorganisms and mammals. However, the physiology of nitrogen metabolism is clearly very different in plants; one example in which this is particularly apparent is the biochemistry associated with photorespiration. In recent years the cloning of some of the genes involved in nitrogen metabolism has enabled cell-specific expression and metabolic regulation type experiments to be undertaken, which in turn directly address questions relating to metabolism and physiology in plants.