Interaction of Phospholipase A of the E. coli Outer Membrane with the Inhibitors of Eucaryotic Phospholipases A2 and Their Effect on the Ca2+-Induced Permeabilization of the Bacterial Membrane
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Phospholipase A of the bacterial outer membrane (OMPLA) is a β-barrel membrane protein which is activated under various stress conditions. The current study examines interaction of inhibitors of eucaryotic phospholipases A2—palmitoyl trifluoromethyl ketone (PACOCF3) and aristolochic acid (AA)—with OMPLA and considers a possible involvement of the enzyme in the Ca2+-dependent permeabilization of the outer membrane of Escherichia coli. Using the method of molecular docking, it has been predicted that PACOCF3 and AA bind to OMPLA at the same site and with the same affinity as the OMPLA inhibitors, hexadecanesulfonylfluoride and bromophenacyl bromide, and the substrate of the enzyme palmitoyl oleoyl phosphatidylethanolamine. It has also been shown that PACOCF3, AA, and bromophenacyl bromide inhibit the Ca2+-induced temperature-dependent changes in the permeability of the bacterial membrane for the fluorescent probe propidium iodide and suppressed the transformation of E. coli cells with plasmid DNA induced by Ca2+ and heat shock. The cell viability was not affected by the eucaryotic phospholipases A2 inhibitors. The study discusses a possible involvement of OMPLA in the mechanisms of bacterial transmembrane transport based on the permeabilization of the bacterial outer membrane.
KeywordsOMPLA Escherichia coli Calcium Permeabilization
We are grateful to Prof. Galina D. Mironova for fruitful discussion. This work was supported by a grant from the Russian Foundation for Basic Research to K.N. Belosludtsev (12-04-00430a) and RF Presidential program for Support of Young Russian Scientists to K.N. Belosludtsev (MK-145.2012.4).
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