The QseC adrenergic signaling cascade in Enterohemorrhagic E. coli (EHEC).

The ability to respond to stress is at the core of an organism's survival. The hormones epinephrine and norepinephrine play a central role in stress responses in mammals, which require the synchronized interaction of the whole neuroendocrine system. Mammalian adrenergic receptors are G-coupled protein receptors (GPCRs); bacteria, however, sense these hormones through histidine sensor kinases (HKs).

The QseC sensor kinase: a bacterial adrenergic receptor.

Quorum sensing is a cell-to-cell signaling mechanism in which bacteria respond to hormone-like molecules called autoinducers (AIs). The AI-3 quorum-sensing system is also involved in interkingdom signaling with the eukaryotic hormones epinephrine/norepinephrine. This signaling activates transcription of virulence genes in enterohemorrhagic Escherichia coli O157:H7.

Transcriptional autoregulation by quorum sensing Escherichia coli regulators B and C (QseBC) in enterohaemorrhagic E. coli (EHEC).

The cell-to-cell communication system referred to as quorum sensing (QS) is based on the principle that bacteria secrete hormone-like compounds referred to as autoinducers. Upon reaching a threshold concentration, these autoinducers interact with transcription factors to regulate gene expression. We previously reported that enterohaemorrhagic Escherichia coli (EHEC), which is responsible for outbreaks of bloody diarrhoea, utilizes a QS system to regulate gene transcription.

Transcriptional regulation of flhDC by QseBC and sigma (FliA) in enterohaemorrhagic Escherichia coli.

Enterohaemorrhagic Escherichia coli (EHEC) serotype O157:H7, the causative agent of haemorrhagic colitis, has been shown to utilize a cell-to-cell signalling system to regulate gene expression. We have previously reported that the quorum sensing E. coli regulators B and C (QseBC) may act as a two-component system in EHEC to transcriptionally regulate the expression of flagella and motility through flhDC, the master regulator of flagella and motility genes.

Events at the host-microbial interface of the gastrointestinal tract III. Cell-to-cell signaling among microbial flora, host, and pathogens: there is a whole lot of talking going on.

Humans have an important association with their intestinal microbial flora. The microbial flora helps to shape the mammalian innate immune system, absorbs nutrients, and plays an intricate role on intestinal development. Microbes and mammals communicate with each other through an array of hormone and hormonelike chemical compounds.