“Universal” Antimicrobial Combination of Bacitracin and His6-OPH with Lactonase Activity, Acting against Various Bacterial and Yeast Cells

Abstract

The effect of Bacitracin as an antibiotic acting against Gram-positive bacterial cells was evaluated in combination with hexahistidine-containing organophosphate hydrolase (His6-OPH), possessing lactonase activity against various N-acylhomoserine lactones produced by most Gram-negative bacteria as quorum-sensing molecules. The molecular docking technique was used to obtain in silico confirmation of possible interactions between molecules of His6-OPH and Bacitracin as well as the absence of a significant influence of such interactions on the enzymatic catalysis. The in vitro experiments showed a sufficient catalytic efficiency of action of the His6-OPH/Bacitracin combination as compared to the native enzyme. The notable improvement (up to 3.3 times) of antibacterial efficiency of Bacitracin was revealed in relation to Gram-negative bacteria when it was used in combination with His6-OPH. For the first time, the action of the Bacitracin with and without His6-OPH was shown to be effective against various yeast strains, and the presence of the enzyme increased the antibiotic effect up to 8.5 times. To estimate the role of the enzyme in the success of His6-OPH/Bacitracin with yeast, in silico experiments (molecular docking) with various fungous lactone-containing molecules were undertaken, and the opportunity of their enzymatic hydrolysis by His6-OPH was revealed in the presence and absence of Bacitracin.

Synergistic Antimicrobial Action of Lactoferrin-Derived Peptides and Quorum Quenching Enzymes

“…Combination of QQ enzymes with antimicrobial agents is one of the most current and effective solutions in antimicrobial therapy. For example, it has been demonstrated that the use of YtnP lactonase in combination with antibiotics leads in an increase in its efficacy in the treatment of systemic Pseudomonas aeruginosa infections [ 31 , 49 ]. The interest in conducting this study was based on the desire of the authors to explore the possibility of combining lactoferrin-derived AMPs with lactone-hydrolyzing enzymes, His 6 -OPH and PvdQ acylase to obtain antimicrobials with improved action against various microorganisms by combining AMPs with QQ-enzymes.…”

“…To accumulate biomass, the cells of bacteria were aerobically cultivated in the corresponding culture medium as described previously [ 33 , 49 ]. Yeast cells were grown in the corresponding culture medium as it was described previously [ 31 ]. The bacterial and yeast cells were cultivated using a thermostatically controlled Adolf Kuhner AG shaker (Basel, Switzerland) at 28 °C for G(−) and yeasts and 30 °C for G(+), with constant stirring at 150 rpm.…”

“…Such enzymes include lactonases and acylases capable of hydrolyzing lactone-containing QS signaling molecules [ 29 , 30 ]. The use of QQ enzymes in combination with clinical antibiotics is one of the most popular modern methods in antimicrobial therapy aimed at destabilizing microorganism cells by inhibiting their QS and restoring their sensitivity to the antibiotics used [ 31 ].…”

Carrier Variety Used in Immobilization of His6-OPH Extends Its Application Areas

“…The most appropriate practical application of His 6 -OPH, in this case, seems to be in combination with antimicrobials, which can have a major suppressive effect on microbial cells; then, the enzyme becomes a tool for weakening the resistance of cells to antimicrobial effects. Since the presence of antimicrobial agents can have a negative effect on the manifestation of enzyme activity, a significant role is currently assigned to computer methods of molecular modeling [ 4 , 6 , 46 , 60 , 61 , 62 , 63 ], including the search for the most successful partners to create effective antimicrobial combinations based on His 6 -tagged OPH [ 64 , 65 , 66 , 67 ]. At the same time, on the basis of the data obtained, as a rule, several important parameters can be estimated: the localization of molecules stabilizing the dimer of the enzyme on its surface, the possible overlap of the active cents of the enzyme, and the affinity of the interaction between the molecules of the “partners” [ 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ].…”

“…As it was found, various polyelectrolytes can act as such enzyme-stabilizing molecules ( Table 2 ); these molecules themselves do not possess antimicrobial properties, but they can be used in antimicrobial preparations [ 64 , 65 , 68 ]. However, the most interesting options are those when the molecules involved in the stabilization of the enzyme themselves have antimicrobial action [ 19 , 65 , 66 , 67 , 68 , 70 ]. These compounds include various so-called antimicrobial polypeptides (AMPs), which are usually of natural origin and can be synthesized by different living organisms.…”