Methionine Biosynthesis in Escherichia coli and Corynebacterium glutamicum

Abstract

The sulphur-containing amino acid methionine and its derivatives play important roles in cellular metabolism. These include initiation of protein biosynthesis, methyl transfer and synthesis of polyamines. Methionine cannot be synthesized by humans and animals and must therefore be obtained from the diet. Since concentrations of methionine in plant-based diets are low, the amino acid is routinely added to animal feed. For this purpose methionine is produced in large scale by chemical synthesis. Currently, no fermentative methionine production process exists, but for economic reasons its development has recently received increasing attention. Research has mainly focused on methionine biosynthesis in the bacteria Escherichia coli and Corynebacterium glutamicum, which are already used for the production of several other amino acids. Investigation of methionine biosynthesis and its regulation in C. glutamicum has revealed major differences with the corresponding E. coli metabolism. This review intends to summarize the current knowledge on methionine biosynthesis in these organisms and discusses approaches for the construction of methionine producer strains.