Oxidative stress-induced expression of catalases in Comamonas terrigena.

When grown under oxidative stress, catalatic as well as peroxidatic activity is increased in the Gram-negative bacterium Comamonas terrigena N3H. Two distinct hydroperoxidases were demonstrated by a specific staining. Based on their molar masses and their sensitivity toward 3-amino-1,2,4-triazole and high temperatures, they were identified as dimeric catalase-1 (Cat-1; 150 kDa), and as a tetrameric catalase-2 (Cat-2; 240 kDa) with enhanced peroxidatic activity, respectively. These two catalases differ in their expression during the bacterial growth; whereas the expression of the smaller enzyme (Cat-1) is induced by 0.5 mmol/L peroxides in the medium, and to a lesser degree by 25 mg/L Cd2+, Cat-2 (typical catalase) is almost specifically induced with cadmium ions.