Sulfonamide inhibition profile of the γ-carbonic anhydrase identified in the genome of the pathogenic bacterium Burkholderia pseudomallei the etiological agent responsible of melioidosis

A new gamma-carbonic anhydrase (CA, EC 4.1.1.1) was cloned and characterized kinetically in the genome of the bacterial pathogen Burkholderia pseudomallei, the etiological agent of melioidosis, an endemic disease of tropical and sub-tropical regions of the world. The catalytic activity of this new enzyme, BpsCA gamma, is significant with a k(cat) of 5.3 x 10(5) s(-1) and k(cat)/K-m, of 2.5 x 10(7) M-1 x s(-1) for the physiologic CO2 hydration reaction. The inhibition constant value for this enzyme for 39 sulfonamide inhibitors was obtained. Acetazolamide, benzolamide and metanilamide were the most effective (K(1)s of 149-653 nM) inhibitors of BpsCA gamma activity, whereas other sulfonamides/sulfamates such as ethoxzolamide, topiramate, sulpiride, indisulam, sulthiame and saccharin were active in the micromolar range (K(1)s of 1.27-9.56 mu M). As Burkholderia pseudomallei is resistant to many classical antibiotics, identifying compounds that interfere with crucial enzymes in the B. pseudomallei life cycle may lead to antibiotics with novel mechanisms of action. (C) 2016 Elsevier Ltd. All rights reserved.