1887

Abstract

uses the two major quorum-sensing (QS) regulatory systems and to modulate the expression of many of its virulence factors. The system is considered to stand at the top of the QS hierarchy. However, some virulence factors such as pyocyanin have been reported to still be produced in mutants under certain conditions. Interestingly, such mutants arise spontaneously under various conditions, including in the airways of cystic fibrosis patients. Using transcriptional reporters, LC/MS quantification and phenotypic assays, we have investigated the regulation of QS-controlled factors by the system. Our results show that activity of the system is only delayed in a mutant, thus allowing the expression of multiple virulence determinants such as pyocyanin, rhamnolipids and C-homoserine lactone (HSL) during the late stationary phase. Moreover, at this stage, RhlR is able to overcome the absence of the system by activating specific LasR-controlled functions, including production of 3-oxo-C-HSL and quinolone signal (PQS). is thus able to circumvent the deficiency of one of its QS systems by allowing the other to take over. This work demonstrates that the QS hierarchy is more complex than the model simply presenting the system above the system.

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2009-03-01
2019-12-13
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The delay in pyocyanin expression in a mutant is not due to secondary mutation or to a difference in the concentration of living cells [ PDF] (16 kb) Protease activity is expressed by a mutant but not by a mutant [ PDF] (59 kb)

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The delay in pyocyanin expression in a mutant is not due to secondary mutation or to a difference in the concentration of living cells [ PDF] (16 kb) Protease activity is expressed by a mutant but not by a mutant [ PDF] (59 kb)

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