The Emerging Role of Urease as a General Microbial Virulence Factor

Urea is generated in humans following the breakdown of amino acids and is evenly distributed throughout the body, including in the central nervous system, subcutaneous adipose tissue, blood serum, and epithelial lining fluid [1,2]. Various pathogenic microbes are able to utilise urea as a nitrogen source through the activity of the enzyme urease that converts urea into ammonia and carbamic acid, with the spontaneous hydrolysis of carbamic acid to carbonic acid generating a further ammonia molecule. CH4N2O+H2ORNH3+CH3NO2 CH3NO2+H2ORNH3+H2CO3 Under physiological conditions the proton of carbonic acid dissociates, and the ammonia molecules become protonated to form ammonium, causing an increase in local pH that can interfere with host function. The role of urease in the virulence of some bacterial pathogens is well established; however, more recent studies are beginning to highlight the function of urease during human fungal infections, suggesting that this enzyme has a wide role during microbial infection.