The physically linkedhisGandhisEgenes, encoding for ATP-phosphoribosyltransferase and phosphoribosyl-ATP-pyrophosphohydrolase were isolated from theCorynebacterium glutamicumgene library by complementation ofEscherichia colihistidine auxotrophs. They are two of the nine genes that participate in the histidine biosynthetic pathway. Molecular genetics and sequencing analysis of the cloned 9-kb insert DNA showed that it carries thehisGandhisEgenes. In combining this result with our previous report, we propose that all histidine biosynthetic genes are separated on the genome by three unlinked loci. The coding regions of thehisGandhisEgenes are 279 and 87 amino acids in length with a predicted size of about 30 and 10 kDa, respectively. Computer analysis revealed that the amino acid sequences of thehisGandhisEgene products were similar to those of other bacteria.