Regulatory Mechanism of Lysine Biosynthetic Genes in Escherichia coli

In Escherichia coli, L-lysine biosynthetic pathway is composed of nine enzymatic reactions. It has been well established that most of the lysine biosynthetic genes are regulated by the lysine availability, even though they are all scattered around the chromosome without forming any multigenic operon structure. However, no transcriptional regulatory mechanism has been identified except for the activation of lysA gene by the LysR. In this study, changes in transcriptome profiles of wild type cells and lysR deletion mutant cells grown in the absence or presence of lysine were investigated by using DNA microarray technique. Microarray data analysis revealed three groups of genes whose expression varies depending on the availability of lysine or LysR or both. To further examine the regulatory patterns of lysine biosynthetic genes, lacZ operon fusions were constructed and their expression was measured under various conditions. Obtained results strongly suggest that there is an additional regulatory mechanism which senses the lysine availability and coordinates gene expression.