Structural and Functional Analysis of Urease Accessory Protein E from Vancomycin-Resistance Staphylococcus aureus MU50 Strain

Background: An increasing prevalence of biofilm forming strains by vancomycinresistance Staphylococcus aureus (VRSA) is one of the most important causes of antimicrobial resistance. VRSA possesses various regulatory factors to form and sustain biofilm in biotic or abiotic conditions. Among them, ureolytic activity is an important factor in the stabilization of biofilms by neutralizing the acidic environment. Various urease accessory proteins are required to activate the urease enzyme inside the biofilm. Objective: To optimize the cloning, expression and purification of urease accessory protein E from VRSA for determination of the secondary structure, and functional characterization by using Berthelot128;™s method. Methods: BAB58453.1 gene (which encodes possible urease accessory protein E), having 38% similarity to Bacillus pasteurii UreE protein, was cloned, expressed, and purified by single-step affinity chromatography for performing secondary structural studies using circular dichroism spectroscopy, and functional analysis using Berthelot128;™s and crystal violet assay. Results: Structure elucidation using NMR and circular dichroism spectroscopy techniques revealed that UreE protein has a partially foldedα-helical structure. Using Berthelot's method, it was identified that the purified UreE protein has enhanced urease enzyme activity, in comparison to the control. From the results of Berthelot128;™s and crystal violet assays, it was deduced that the selected gene (UreE protein) plays a key role in enhancing urease enzyme activity and contributes to biofilm stability. Conclusion: Structural studies on VRSA urease accessory proteins could aid in the identification of new drug targets or the development of effective antibiofilm strategies (in combination with other drug targets) against infections caused by biofilm-producing strains.