Genetically programmed autoinducer destruction reduces virulence gene expression and swarming motility in Pseudomonas aeruginosa PAO1.
Virulence in the opportunistic human pathogen Pseudomonas aeruginosa is controlled by cell density via diffusible signalling molecules ('autoinducers') of the N-acylhomoserine lactone (AHL) type. Two Bacillus sp. isolates (A23 and A24) with AHL-degrading activity were identified among a large collection of rhizosphere bacteria. From isolate A24 a gene was cloned which was similar to the aiiA gene, encoding an AHL lactonase in another Bacillus strain. Expression of the aiiA homologue from isolate A24 in P. aeruginosa PAO1 reduced the amount of the quorum sensing signal N-oxododecanoyl-L-homoserine lactone and completely prevented the accumulation of the second AHL signal, N-butyryl-L-homoserine lactone. This strongly reduced AHL content correlated with a markedly decreased expression and production of several virulence factors and cytotoxic compounds such as elastase, rhamnolipids, hydrogen cyanide and pyocyanin, and strongly reduced swarming. However, no effect was observed on flagellar swimming or on twitching motility, and aiiA expression did not affect bacterial adhesion to a polyvinylchloride surface. In conclusion, introduction of an AHL degradation gene into P. aeruginosa could block cell-cell communication and exoproduct formation, but failed to interfere with surface colonization.
Reimmann
Cornelia
C
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Ginet
Nathalie
N
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Michel
Laurent
L
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Keel
Christoph
C
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Michaux
Patrick
P
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Krishnapillai
Viji
V
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Zala
Marcello
M
Institut für Pflanzenwissenschaften/Phytopathologie, ETH Zürich, CH-8092 Zürich, Switzerland2.
Heurlier
Karin
K
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
Triandafillu
Karine
K
IATE-Pédologie, EPFL, CH 1015 Lausanne, Switzerland3.
Harms
Hauke
H
IATE-Pédologie, EPFL, CH 1015 Lausanne, Switzerland3.
Défago
Geneviève
G
Institut für Pflanzenwissenschaften/Phytopathologie, ETH Zürich, CH-8092 Zürich, Switzerland2.
Haas
Dieter
D
Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
D001407:Bacillus / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D017931:DNA Primers; D006801:Humans; D008969:Molecular Sequence Data; D009068:Movement; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D014774:Virulence / Q000235:genetics*
D017931:DNA Primers