The complete nucleotide sequence of the Corynebacterium glutamicum hom-thrB operon has been determined and the structural genes and promoter region mapped. A polypeptide of Mr 46,136 is encoded by hom and a polypeptide of Mr 32,618 is encoded by thrB. Both predicted protein sequences show amino acid sequence homology to their counterparts in Escherichia coli and Bacillus subtilis. The promoter region has been mapped by S1-nuclease and deletion analysis. Located between -88, RNA start site and -219 (smallest deletion clone with complete activity) are sequence elements similar to those found in E. coli and B. subtilis promoters. Although there are no obvious attenuator-like structures in the 5'-untranslated region, there is a dyad-symmetry element, which may act as an operator.