THE GALE GENE ENCODING THE UDP-GALACTOSE 4-EPIMERASE OF BREVIBACTERIUM-LACTOFERMENTUM IS COUPLED TRANSCRIPTIONALLY TO THE DMDR GENE

The galE gene of Brevibacterium lactofermentum, encoding UDP-galactose 4-epimerase (EC 5.1.3.2), has been identified by DNA sequencing downs tream from the orf1-sigB-dmdR region. The arrangement of the sigB-dtxR -galE cluster is also conserved in Corynebacterium diphtheriae. The de duced galE product was a protein of 329 aa residues (35.4 kDa) that sh ared a high degree of identity to known UDP-galactose 4-epimerase prot eins from Gram-positive microorganisms (Streptomyces lividans and Stre ptococcus thermophilus). Transcriptional analysis of the dmdR and galE genes in nutrient-rich medium showed that these genes are part of an operon, that is actively transcribed as a bicistronic mRNA during the exponential growth phase, but transcription of the operon is decreased during the stationary growth phase. In addition, the dmdR gene was al so expressed as a monocistronic 0.7-kb transcript during the active gr owth phase.