Abstract
Inhibition of ruminal microbial urease is of particular interest due to its crucial role in regulating urea-N utilization efficiency and nitrogen pollution in the livestock industry. Acetohydroxamic acid (AHA) is currently the only commercially available urease inhibitor, but it has adverse side effects. The urease accessory protein UreG, which facilitates the functional incorporation of the urease nickel metallocentre, has been proposed in developing urease inhibitor through disrupting urease maturation. The objective of this study was to screen natural compounds as potential urease inhibitors by targeting UreG in a predominant ruminal microbial urease. In silico screening and in vitro tests for potential inhibitors were performed using molecular docking and an assay for the GTPase activity of UreG. Chelerythrine chloride was selected as a potential urease inhibitor of UreG with an inhibition concentration IC50 value of 18.13 μM. It exhibited mixed inhibition, with the Ki value being 26.28 μM. We further explored its inhibition mechanism using isothermal titration calorimetry (ITC) and circular dichroism (CD) spectroscopy, and we found that chelerythrine chloride inhibited the binding of nickel to UreG and induced changes in the secondary structure, especially the α-helix and β-sheet of UreG. Chelerythrine chloride formed a pi-anion interaction with the Asp41 residue of UreG, which is an important residue in initiating the conformational changes of UreG. In conclusion, chelerythrine chloride exhibited a potential inhibitory effect on urease, which provided new evidence for strategies to develop novel urease inhibitors targeting UreG to reduce nitrogen excretion from ruminants.
Highlights
Urea is commonly used as a cost-efficient replacement of feed proteins to provide the sole nitrogen source for urease [1,2,3]
The final eluted proteins were incubated in 20 mM ethylene diamine tetraacetic acid (EDTA) and 1 mM DL-dithiothreitol (DTT) overnight at 4 ◦C to obtain the apo-form of the proteins, which were collected and buffer-exchanged into HBS buffer (GE, Boston, MA, USA) using a 3 kDa centrifugal filter device (Millipore, Billerica, MA, USA)
This study investigated the inhibition of chelerythrine chloride towards the accessory protein UreG from a predominant ruminal microbial urease
Summary
Urea is commonly used as a cost-efficient replacement of feed proteins to provide the sole nitrogen source for urease [1,2,3]. Ruminant nitrogen is the major source of livestock pollution, with approximately 46 Tg·N·yr−1, equivalent to 71% of the total nitrogen emissions from livestock [7]. The dietary nitrogen utilization efficiency is only about 25% [8,9], with as much as 60–90% of the feed nitrogen being excreted [10]. Regulation of urease activity is crucial to reduce ammonia emissions and improve the efficiency of urea-N utilization in ruminants, and urease inhibitors have been recognized as one of the most effective strategies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
