The autoinducer-3 (AI-3)/epinephrine (Epi)/norepinephrine (NE) interkingdom signaling system mediates chemical communication between bacteria and their mammalian hosts. The three signals are sensed by the QseC histidine kinase (HK) sensor. Salmonella enterica serovar Typhimurium is a pathogen that uses HKs to sense its environment and regulate virulence. Salmonella serovar Typhimurium invades e...

Transcriptional analysis of Salmonella enterica serovar Typhimurium (S. Typhimurium) in the presence of the mammalian hormone norepinephrine revealed up-regulation of genes in the flagellar and chemotaxis regulon. Motility assays confirmed enhanced motility of wild-type S. Typhimurium in the presence of norepinephrine that could be blocked by the alpha-adrenergic antagonist, phentolamine. Furth...

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 (H...

The bacterial adrenergic sensor kinases QseC and QseE respond to epinephrine and/or norepinephrine to initiate a complex phosphorelay regulatory cascade that modulates virulence gene expression in several pathogens. We have previously shown that QseC activates virulence gene expression in Salmonella enterica serovar Typhimurium. Here we report the role of QseE in S. Typhimurium pathogenesis as ...

UNLABELLED Enteric pathogens such as enterohemorrhagic Escherichia coli (EHEC) and Citrobacter rodentium, which is largely used as a surrogate EHEC model for murine infections, are exposed to several host neurotransmitters in the gut. An important chemical exchange within the gut involves the neurotransmitters epinephrine and/or norepinephrine, extensively reported to increase virulence gene ex...

Pectobacterium carotovorum subsp. carotovorum is a well-known plant pathogen that causes severe soft rot disease in various crops, resulting in considerable economic loss. To identify pathogenicity-related factors, Chinese cabbage was inoculated with 5314 transposon mutants of P. carotovorum subsp. carotovorum Pcc21 derived using Tn5 transposon mutagenesis. A total of 35 reduced-virulence or av...

A global vulnerability of an IT infrastructure is a set of vulnerabilities in its nodes that enables a sequence of attacks where an agent acquires the privileges that each attack requires as a result of the previous attacks in the sequence. This paper presents QSec, a tool to support decision on the infrastructure security that queries a database with information on global vulnerabilities and t...

Abstract Actinobacillus pleuropneumoniae (APP) is the major pathogen of porcine contagious (PCP). The QseB/QseC two-component system (TCS) consists regulator QseB and kinase QseC, which relates to quorum sensing (QS) virulence in some bacteria. Here, we investigated role apf gene cluster ( apfABCD ) expression APP. Our results have showed that TCS can potentially regulate cluster. Δ qseBC , apf...

Aggregatibacter actinomycetemcomitans QseBC regulates its own expression and is essential for biofilm growth and virulence. However, the signal that activates the QseC sensor has not been identified and the qseBC regulon has not been defined. In this study, we show that QseC is activated by catecholamine hormones and iron but not by either component alone. Activation of QseC requires an EYRDD m...