title: Quorum sensing: regulating the regulators.
abstract: Many bacteria use 'quorum sensing' (QS) as a mechanism to regulate gene induction in a population-dependent manner. In its simplest sense this involves the accumulation of a signaling metabolite during growth; the binding of this metabolite to a regulator or multiple regulators activates induction or repression of gene expression. However QS regulation is seldom this simple, because other inputs are usually involved. In this review we have focussed on how those other inputs influence QS regulation and as implied by the title, this often occurs by environmental or physiological effects regulating the expression or activity of the QS regulators. The rationale of this review is to briefly introduce the main QS signals used in Gram-negative bacteria and then introduce one of the earliest understood mechanisms of regulation of the regulator, namely the plant-mediated control of expression of the TraR QS regulator in Agrobacterium tumefaciens. We then describe how in several species, multiple QS regulatory systems can act as integrated hierarchical regulatory networks and usually this involves the regulation of QS regulators. Such networks can be influenced by many different physiological and environmental inputs and we describe diverse examples of these. In the final section, we describe different examples of how eukaryotes can influence QS regulation in Gram-negative bacteria.
authors: Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
authors: Marijke
authors: M
authors: Frederix
authors: Allan J
authors: AJ
authors: Downie
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006090:Gram-Negative Bacteria / Q000235:genetics* / Q000378:metabolism*; D006714:Homoserine / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism; D007783:Lactones / Q000378:metabolism; D010957:Plasmids; D053038:Quorum Sensing / Q000235:genetics*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C091100:GacA protein, Bacteria; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D012808:Sigma Factor; C080512:TraR protein, Agrobacterium tumefaciens; C069567:sigma factor KatF protein, Bacteria; D006714:Homoserine