PHYSICAL MAPPING OF THE SCATTERED METHIONINE GENES ON THE ESCHERICHIA-COLI CHROMOSOME

Methionine is an important amino acid which acts not only as a substra te for protein elongation but also as the initiator of protein synthes is. The genes of the met regulon, which consists of 10 biosynthetic ge nes (metA, metB, metC, metE, metF, metH, metK, metL, metQ, and metX), two regulatory genes (metJ and metR), and the methionyl tRNA synthetas e gene (metG), are scattered throughout the chromosome (3). The only l inked genes are metK and metX at 63.6 min, metE and metR at 86.3 min, and the metJBLF gene cluster at 89 min (20). metBL form the only met o peron.