Correlation between the Bacterioclastic Action of a Bis-quaternary Ammonium Compound and Outer Membrane Proteins
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Bis-quaternary ammonium compounds (bis-QACs) have the ability to cause a rapid and abundant leakage of the turbid materials from cells, and such a bacterioclastic ability leads to a potent bactericidal activity. In order to clarify the detailed mechanism of the bactericidal action of bis-QACs, the correlation between the bacterioclastic action of 4, 4'-(1, 6-hexamethylenedithio) bis (1-octylpyridinium bromide) (4DTBP-6, 8) and the leakage of outer membrane pore protein E (OmpE) was investigated. Using the antiserum against a fusion protein consisting of GST and the OmpE protein of <I>Escherichia coil</I> encoded by the ompE gene, it was seen that the leakage of <I>OmpE</I> from <I>E. coil</I> cells was caused by treatment with low concentrations (much lower than the critical vesiculation concentration) of 4DTBP-6, 8. Furthermore, it was confirmed that 4DTBP-6, 8 caused an increase in the turbidity of the cell suspension of <I>Klebsiella pneumoniae, Salmonella typhimurium</I> and <I>Serratia marcescences</I>, and led to the leakage of several proteins which have a high percentage of homology with OmpE of <I>E. coll</I>. By immunoelectron microscopy investigation, it was revealed that the vesiculation from <I>E. coil</I> treated with 4DTBP-6, 8 contains OmpE. In addition, the bacteriolytic action of 4DTBP-6, 8 was investigated. The results suggested that the lysis of cells by bis-QACs was not an enzymatic action such as that by autolysin but a physical bacterioclastic action. Judging from these results, it is suggested that the leakage of OmpE is one of the major bacterioclastic actions of bis-QACs, and deals the bacterial cells a fatal blow.
- Biocontrol Sci.
Biocontrol Sci. 11(3), 115-124, 2006-09-01
The Society for Antibacterial and Antifungal Agents, Japan