The Pseudomonas aeruginosa RhlR-controlled aegerolysin RahU is a low-affinity rhamnolipid-binding protein.
The opportunistic pathogen Pseudomonas aeruginosa uses quorum-sensing systems to regulate collective behaviour in response to the environment, by linking the expression of particular genes to population density. The quorum-sensing transcription factors LasR and RhlR and their cognate N-acyl-homoserine lactone (HSL) signals N-3-oxo-dodecanoyl-L-HSL (3OC12-HSL) and N-butanoyl-L-HSL (C4-HSL) control the expression of several hundred genes, which include those involved in virulence and biofilm formation. Here, we have focused on regulation of the expression of the putative virulence factor gene, rahU. We show that the intact las-rhl box immediately upstream of the -35 promoter element is needed for rahU expression in P. aeruginosa. Using β-galactosidase assays and quantification of the mRNA levels for rahU, lasR and rhlR, we provide evidence that for rahU promoter activity, 3OC12-HSL-LasR is not sufficient, and instead C4-HSL-RhlR is the trigger. Furthermore, surface plasmon resonance analysis revealed that RahU binds the biosurfactant rhamnolipids. Thus, this is the first report of a bacterial molecule that interacts with RahU.
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Špela
Š
Miklavič
Department of Biotechnology and Systems Biology, National Institute of Biology, 1000 Ljubljana, Slovenia.
Polona
P
Kogovšek
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Vesna
V
Hodnik
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Jernej
J
Korošec
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Aleš
A
Kladnik
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia National Institute of Chemistry, 1000 Ljubljana, Slovenia.
Gregor
G
Anderluh
Department of Biotechnology and Systems Biology, National Institute of Biology, 1000 Ljubljana, Slovenia.
Ion
I
Gutierrez-Aguirre
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Peter
P
Maček
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia matej.butala@bf.uni-lj.si.
Matej
M
Butala
D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006017:Glycolipids / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D053038:Quorum Sensing; D020349:Surface Plasmon Resonance; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
D005656:Fungal Proteins; D006017:Glycolipids; D006460:Hemolysin Proteins; D037521:Virulence Factors; C461279:aegerolysin; C418382:rhamnolipid
biosurfactant; induction of gene expression; quorum-sensing; rhamnolipids; transcription responses