Vibrio: Caenorhabditis elegans as a Laboratory Model for Vibrio Infections
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
The genetic approach for identifying genes regulating the virulent pathway in V. parahaemolyticus showed a close association between the urease gene and the TRH gene.60 Hence, it is hypothesized that possession of the gene for TRH coincides with the presence of the urease gene among many clinical V. parahaemolyticus strains, making urease gene a marker for identifying clinically pathogenic trh positive strains.61 Urease is an enzyme involved in the hydrolysis of urea into ammonia and carbon dioxide and is present across kingdoms in plants, fungi, algae, and bacteria.62 Many bacterial ureases have been characterized, and the organization of this gene is found to be similar among bacteria with regard to the structural and accessory genes involved in processing nickel ions.63 Comparing with other Vibrio spp., only a small portion of clinical V. parahaemolyticus isolates possess the urease gene.61 But the presence of urease gene is always associated with presence of trh gene. Specialized PCR techniques such as the long and accurate PCR have revealed that the distance between these two genes is <8.5 kb.64
Proteus
Dongyou Liu in Handbook of Foodborne Diseases, 2018
Urease is an enzyme responsible for the hydrolysis of urea to ammonia and carbon dioxide and is produced by P. mirabilis [58]. The end products have the effect of increasing the environmental pH, mainly in urine, and this induces the precipitation of magnesium and calcium ions, normally soluble in urine. These crystals become trapped within the polysaccharides produced by attached bacteria, forming the characteristic crystalline biofilm on the catheter's surface [59]. Moreover, this change in pH and the precipitation of ions stimulate the formation of urinary stones containing struvite and carbonate apatite. Bacteria present within urinary stones are protected from host defense mechanisms and antibiotic treatment [60]. The activity of this enzyme is indirectly cytotoxic over the urothelium, causing tissue damage [61].
Role of Bacteria in Urinary Tract Infections
K. Balamurugan, U. Prithika in Pocket Guide to Bacterial Infections, 2019
Urease is an enzyme used for the hydrolysis of urea. A healthy individual produces about 30 g of urea per day (Newsholme & Leech, 2011). Most of the UTI pathogens have urease activity as a part of its virulence character. The urease-dependent process is associated with bacterial UTI, including those caused by Proteus and Staphylococcal spp. Urease produced by these bacteria can lead to the formation of stones because of the precipitation of the minerals struvite and carbonate apatite. The stone formation is used to protect the pathogen (Griffith et al., 1976). These stones can block the flow of urine and lead to tissue damage (Schaffer & Pearson, 2015) Ammonia produced during the above process can damage the glycosaminoglycan surface of the urothelium, and it will allow the entry for the other bacterial infections (Rutherford, 2014). It was shown that urease from Proteus mirabilis can hydrolyze urea several times faster than urease synthesized by other species of bacteria (Jordan & Nicolle, 2014).
Amelioration of Diabetes-Induced Diabetic Nephropathy by Aloe vera: Implication of Oxidative Stress and Hyperlipidemia
Published in Journal of Dietary Supplements, 2019
Mandeep Kumar Arora, Yogesh Sarup, Ritu Tomar, Mary Singh, Puspendra Kumar
The blood urea was estimated by Berthelot method (Fawcett & Scott, 1960) using the commercially available kit (ERBA, Transasia Bio-Medicals Ltd., Solan, India). The amount of 1,000 µl of working reagent-I containing urease reagent, and a mixture of salicylate, hypochlorite, and nitroprusside was added to 10 µl of serum, 10 µl of standard urea (40 mg/dl), and 10 µl of purified water to prepare test, standard, and blank, respectively. All test tubes were mixed well and incubated at 37°C for 5 min. Then 1,000 µl of reagent-II containing alkaline buffer was added to all the test tubes, which were incubated at 37°C for 5 min. Urease catalyzes the conversion of urea to ammonia and carbon dioxide. The ammonia thus released reacts with a mixture of salicylate, hypochlorite, and nitroprusside to yield indophenol, a blue-green–colored compound. The intensity of the color produced is directly proportional to the concentration of urea in the sample and is measured spectrophotometrically at 578 nm. The blood urea was calculated using the following formula:
An overview: metal-based inhibitors of urease
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Wei Yang, Zhiyun Peng, Guangcheng Wang
Urease (EC 3.5.1.5, urea amide hydrolase) is a natural enzyme strictly dependent on the metal ion nickel, widely distributed in fungi, bacteria, algae, plants, and other species 1,2. Besides, urease can catalyse the hydrolysis of urea to form carbamic acid and ammonia 3,4. In 1995, the first complete structures of three-dimensional urease have been reported via the crystallographic study of Klebsiella aerogenes urease5. Since then, the researchers have elucidated other structures of ureases from Canavalia ensiformis6, Pasteurella7, and Helicobacter pylori (H. pylori)8. Moreover, the structure of urease contains heteromeric molecules with three subunits α, β, and γ9, and the active site of urease is located in the α subunit, which has two Ni2+ (Ni1 and Ni2) centres10. Additionally, these two nickel ions are essential in the general mechanism of catalysis by urease7. One of the nickel ions is responsible for binding and activating urea, while the other binds and activates nucleophilic water molecules7. When the water molecules are replaced, the N atom of amino on the urea combines with Ni2, which promotes the release of NH3 and carbamate7.
Integrated hypothesis of dental caries and periodontal diseases
Published in Journal of Oral Microbiology, 2020
Bente Nyvad, Nobuhiro Takahashi
Some common bacteria in the supragingival plaque, such as Actinomyces and Streptococcus, possess urease [16], which quickly breaks down urea into ammonia and carbon dioxide, and neutralizes bacteria-derived acids. Bacterial urease can function at a wide range of pH while keeping high activity at acid pH [57]. Other metabolic pathways, such as bacterial amino acid fermentation, the arginine/agmatine deiminase system and amino acid decarboxylation are also known to neutralize environmental pH (Figure 2) [16]. In addition, bacteria-derived acids can be degraded or converted into weaker acids via lactate degradation, formate degradation, malolactic reaction, and acid conversion (Figure 2) [16]. These acidification and acid-neutralization/alkalization processes that occur repeatedly in the supragingival plaque counteract each other and limit major pH-fluctuations exceeding the 5.5–7 range between meals.
Related Knowledge Centers
- Amidohydrolase
- Ammonia
- Bacteria
- Carbon Dioxide
- Catalysis
- Enzyme
- Hydrolysis
- Metalloprotein
- Urea
- Protein Family