Soo-suk Lee

Organization and analysis of the histidine biosynthetic genes fromCorynebacterium glutamicum

Corynebacterium glutamicum, a Gram-positive bacterium, has been widely used for industrial amino acid production. In addition to our previously clonedhisEG andhisHA-impA-hisFI genes, the remaininghisDCB genes were cloned in this study. The entireC. glutamicum histidine biosynthesis genes, when compared with those of other microorganisms, showed high degree of similarities in deduced amino acid sequences but also significant differences in gene organization. Transcription analysis by RT-PCR revealed thatC. glutamicum his genes are located and transcribed in two unlinked loci,hisEG andhisDCB-orf1-orf2-hisHA-impA-hisFI. The primer extension analysis showed that the latterhis operon starts the transcription at C residue localized 196-bp upstream of thehisD ATG start codon. Genetic analysis inhisD promoter region showed the putative Pribnow boxes, TTTAAT and CAGTAT at 7 and 31 upstream ofhisD gene transcription start site. Further analysis revealed Shine-Dalgarno sequence, AGGGAG, at 10-bp upstream ofhisD translational start codon. Our result also suggests that the histidine biosynthesis inC. glutamicum is negatively regulated by their end-product, histidine, suggesting the histidine-dependent regulation ofhis gene transcription.