Cloning of Lactobacillus plantarum IAM 12477 lysine biosynthetic genes encoding functional aspartate semialdehyde dehydrogenase, dihydrodipicolinate synthase, and dihydrodipicolinate reductase

Summary The lysine biosynthetic genes asd, dapA, and dapB, encoding aspartate semialdehyde dehydrogenase (ASADH), dihydrodipicolinate synthase (DHPS), and dihydrodipicolinate reductase (DHPR), respectively, have been cloned from Lactobacillus plantarum IAM 12477 by heterologous complementation to Escherichia coli mutants. The amino acid sequences of the cloned genes showed considerable similarities to the corresponding protein from other gram-positive bacteria. We identified the amino acids that correspond to key catalytic residues of ASADH, DHPS, and DHPR and found them to be conserved in the protein from L. plantarum. ASADH, DHPS, and DHPR activity was detected in the cell extracts of E. coli mutant harboring each gene, indicating that the cloned genes were functionally expressed in E. coli. The regulation of ASADH, DHPS, and DHPR were studied in the cell extracts of both the E.␣coli mutant harboring the gene and L. plantarum; however, those enzymes were found not to be regulated by the end products of the pathway. This paper represents a portion of the thesis submitted by M. N. Cahyanto to Osaka University as partial fulfillment of the requirements for the PhD degree.