SummaryThe genes encoding the three terminal enzymes in the threonine biosynthetic pathway, homoserine dehydrogenasa (hom), homoserine kinase (thrB) and threonine synthase (thrC) have been isolated fromCorynebacterium glutamicum.TheC. glutamicum homandthrBgenes were subcloned on a 3.6 kbSall‐generated chromosomal fragment. TheC. glutamicum thrCgene was shown not to be linked to thehom‐thrBlocus. L‐methionine represses the cloned homoserine dehydrogenase and homoserine kinase similar to that of the chromosomally encodedhomandthrBgene products. Northern hybridization analysis demonstrates that this repression is mediated at the level of transcription and thathom‐thrBrepresents an operon inC. glu