AstR-AstS, a new two-component signal transduction system, mediates swarming, adaptation to stationary phase and phenotypic variation in Photorhabdus luminescens.
Photorhabdus luminescens is an insect-pathogenic bacterium that forms a symbiosis with specific entomopathogenic nematodes. In this bacterium, a symbiosis-'deficient' phenotypic variant (known as the secondary variant or form II) arises at a low frequency during prolonged incubation. A knock-out mutant was generated of the regulator of a newly identified two-component regulatory system, designated AstR-AstS. Interestingly, this mutation altered the timing of phenotypic switching. Variant cells arose in the mutant strain several days before they did in the wild-type population, suggesting that AstRS is directly or indirectly involved in the genetic mechanism underlying variant cell formation. This mutation also affected motility and antibiotic synthesis. To identify AstRS-regulated genes, a comparative analysis using two-dimensional gel electrophoresis was performed. Seventeen proteins with modified synthesis in stationary phase were identified by mass spectrometry and shown to be involved in electron-transport systems, energy metabolism, iron acquisition and stress responses. The results imply that AstRS is involved in the adaptation of cells to the stationary phase, whilst negatively affecting the competitive advantage of form I cells. The link between AstRS-dependent stationary-phase adaptation and phenotypic variation is discussed.
Derzelle
Sylviane
S
Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Ngo
Saravuth
S
Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Turlin
Évelyne
É
Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Duchaud
Éric
É
Laboratoire de Génomique des Micro-organismes Pathogènes, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Namane
Abdelkader
A
Plate-forme Technologique Protéomique, Institut Pasteur, 75724 Paris Cedex 15, France.
Kunst
Frank
F
Laboratoire de Génomique des Micro-organismes Pathogènes, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Danchin
Antoine
A
Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Bertin
Philippe
P
Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
Charles
Jean-François
JF
Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France.
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009154:Mutation; D009348:Nematoda / Q000382:microbiology; D010641:Phenotype; D020637:Photorhabdus / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D018411:Spodoptera / Q000382:microbiology; D013559:Symbiosis; D014774:Virulence
D001426:Bacterial Proteins