Abstract
The interbacterial communication system known as quorum sensing (QS) utilizes hormone-like compounds referred to as autoinducers to regulate bacterial gene expression. Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is the agent responsible for outbreaks of bloody diarrhea in several countries. We previously proposed that EHEC uses a QS regulatory system to "sense" that it is within the intestine and activate genes essential for intestinal colonization. The QS system used by EHEC is the LuxS/autoinducer 2 (Al-2) system extensively involved in interspecies communication. The autoinducer Al-2 is a furanosyl borate diester whose synthesis depends on the enzyme LuxS. Here we show that an EHEC luxS mutant, unable to produce the bacterial autoinducer, still responds to a eukaryotic cell signal to activate expression of its virulence genes. We have identified this signal as the hormone epinephrine and show that β- and α-adrenergic antagonists can block the bacterial response to this hormone. Furthermore, using purified and in vitro synthesized Al-2 we showed that Al-2 is not the autoinducer involved in the bacterial signaling. EHEC produces another, previously undescribed autoinducer (Al-3) whose synthesis depends on the presence of LuxS. These results imply a potential cross-communication between the luxS/Al-3 bacterial QS system and the epinephrine host signaling system. Given that eukaryotic cell-to-cell signaling typically occurs through hormones, and that bacterial cell-to-cell signaling occurs through QS, we speculate that QS might be a "language" by which bacteria and host cells communicate.
Original language | English (US) |
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Pages (from-to) | 8951-8956 |
Number of pages | 6 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 100 |
Issue number | 15 |
DOIs | |
State | Published - Jul 22 2003 |
Externally published | Yes |
Keywords
- Enterohemorrhagic Escherichia coli
- Epinephrine
- Quorum sensing
- Type III secretion
ASJC Scopus subject areas
- General