Structure of the urease operon of Corynebacterium glutamicum

Urease activity of Corynebacterium glutamicum results in a rapid pH increase upon addition of urea to the growth medium. The urease operon C. glutamicum was isolated of and sequenced. Seven open reading frames were identified; ureA, ureB, and ureC were homologues of other bacterial urease structural genes, ureE, ureF, ureG, and ureD exhibited homology to urease accessory genes. Disruption of ureC prevented the utilization of urea as a nitrogen source by C. glutamicum. Urease activity was induced by urea and appeared to be independent of the nitrogen regulatory system. Urease activity was not affected by pH. Heterologous expression of a truncated derivative of the urease gene cluster in Escherichia coli showed that ureD was necessary for active expression. Western-blot and primer extension analysis on C. glutamicum grown under different conditions confirmed that the operon was induced by urea. Transcriptional startpoint for the ureA gene was determined.