Antibacterial activity of curcumin via apoptosis-like response in Escherichia coli
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Curcumin, a naturally occurring phenolic compound, has been shown to exhibit antimicrobial activity against Candida albicans, Escherichia coli, Pseudomonas aeruginosa, etc., but the mechanism remains unclear. The present study was designed to investigate the novel antibacterial mechanism of curcumin that shows an apoptosis-like response in E. coli. We found that curcumin induces membrane damage at relatively high concentrations, but there was no effect at the minimum inhibitory concentration (MIC). At the MIC, curcumin-treated cells displayed various apoptotic markers such as reactive oxygen species (ROS) accumulation, membrane depolarization, and Ca2+ influx. Expression of RecA protein, which mediates a bacterial apoptosis-like response, was also increased by curcumin. In order to evaluate the influence of RecA on the appearance of other apoptotic markers, phosphatidylserine (PS) exposure and DNA fragmentation were examined and compared with a RecA deletion strain (ΔRecA). These markers were detected in E. coli wild-type cells, but not in ΔRecA cells. In conclusion, our data demonstrate that curcumin induces an apoptosis-like response in E. coli that involves RecA.
KeywordsApoptosis-like response Curcumin Escherichia coli RecA
This work was supported by a grant from the National Research Foundation of Korea (NRF), funded by the government of Korea (MSIP) (No. 2015R1A5A6001906). KEIO ΔRecA was provided by Prof. Dong-Woo Lee (Kyungpook National University).
Compliance with ethical standards
This article does not contain any studies with human or animals subjects.
Conflict of interest
The authors declare that they have no competing interests.
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