Effects of the Quinone Oxidoreductase WrbA on Escherichia coli Biofilm Formation and Oxidative Stress

Abstract

The effects of natural compounds on biofilm formation have been extensively studied, with the goal of identifying biofilm formation antagonists at sub-lethal concentrations. Salicylic and cinnamic acids are some examples of these compounds that interact with the quinone oxidoreductase WrbA, a potential biofilm modulator and an antibiofilm compound biomarker. However, WrbA’s role in biofilm development is still poorly understood. To investigate the key roles of WrbA in biofilm maturation and oxidative stress, Escherichia coli wild-type and ∆wrbA mutant strains were used. Furthermore, we reported the functional validation of WrbA as a molecular target of salicylic and cinnamic acids. The lack of WrbA did not impair planktonic growth, but rather affected the biofilm formation through a mechanism that depends on reactive oxygen species (ROS). The loss of WrbA function resulted in an ROS-sensitive phenotype that showed reductions in biofilm-dwelling cells, biofilm thickness, matrix polysaccharide content, and H2O2 tolerance. Endogenous oxidative events in the mutant strain generated a stressful condition to which the bacterium responded by increasing the catalase activity to compensate for the lack of WrbA. Cinnamic and salicylic acids inhibited the quinone oxidoreductase activity of purified recombinant WrbA. The effects of these antibiofilm molecules on WrbA function was proven for the first time.

Pseudomonas aeruginosa Nonphosphorylated AlgR Induces Ribonucleotide Reductase Expression under Oxidative Stress Infectious Conditions

“…To evaluate whether AlgR regulates RNR expression under oxidative stress conditions during infection, we measured RNR induction in a continuous biofilm, which can simulate an infection-like situation ( 24 ). Other studies have already measured ROS in biofilms and have shown the importance of this growth condition during infection ( 25 ). In our experiments, we used a continuous flow biofilm to measure nrdJ and nrdA expression under oxidizing conditions ( Fig.…”

Unlocking the Antibiofilm Potential of Natural Compounds by Targeting the NADH:quinone Oxidoreductase WrbA

“…Later, using a similar pull-down approach, WrbA was identified as the protein interacting with the antibiofilm molecule T315, a phenyl-pyrazole analog that targets the etiological agent of typhoid fever, Salmonella enterica serovar Typhi [ 24 ]. SA, as well as the ZA-analogous compound cinnamic acid (CA), exhibited an antibiofilm effect at non-lethal concentrations [ 21 , 23 ] and demonstrated inhibition of the NADH-dependent oxidoreductase function of E. coli WrbA [ 25 , 26 ]. A WrbA-deprived (∆ wrb A) mutant strain of E. coli was used to prove the involvement of WrbA in biofilm formation, which occurs through a mechanism dependent on the ROS level [ 25 ].…”

“…SA, as well as the ZA-analogous compound cinnamic acid (CA), exhibited an antibiofilm effect at non-lethal concentrations [ 21 , 23 ] and demonstrated inhibition of the NADH-dependent oxidoreductase function of E. coli WrbA [ 25 , 26 ]. A WrbA-deprived (∆ wrb A) mutant strain of E. coli was used to prove the involvement of WrbA in biofilm formation, which occurs through a mechanism dependent on the ROS level [ 25 ]. The lack of WrbA function resulted in a ROS-sensitive phenotype characterized by a reduced number of biofilm-dwelling cells, decreased biofilm thickness, lower matrix polysaccharide content, and reduced tolerance to hydrogen peroxide [ 25 ].…”

“…A WrbA-deprived (∆ wrb A) mutant strain of E. coli was used to prove the involvement of WrbA in biofilm formation, which occurs through a mechanism dependent on the ROS level [ 25 ]. The lack of WrbA function resulted in a ROS-sensitive phenotype characterized by a reduced number of biofilm-dwelling cells, decreased biofilm thickness, lower matrix polysaccharide content, and reduced tolerance to hydrogen peroxide [ 25 ]. The study conducted by Ratti et al [ 26 ] elucidated the underlying mechanisms behind the antibiofilm effect of ellagic acid (EA).…”

Understanding the Role of the Antioxidant Drug Erdosteine and Its Active Metabolite on Staphylococcus aureus Methicillin Resistant Biofilm Formation

“…For example, salicylic acid, the active component of aspirin, has been proved to interact with the quinone oxidoreductase WrbA, reducing Escherichia coli biofilm through a mechanism that depends on ROS [ 5 , 7 ]. N-acetylcysteine is used as mucolytic drug and it is applied on a broad range of pathologies with the primary role of antioxidant agent [ 8 ].…”