GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens.
The concentration of GABA increases rapidly in wounded plant tissues, but the implication of this GABA pulse for plant-bacteria interactions is not known. Here we reveal that GABA stimulated the inactivation of the N-(3-oxooctanoyl)homoserine lactone (OC8-HSL) quorum-sensing signal (or "quormone") by the Agrobacterium lactonase AttM. GABA induced the expression of the attKLM operon, which was correlated to a decrease in OC8-HSL concentration in Agrobacterium tumefaciens cultures. The Agrobacterium GABA transporter Bra was required for this GABA-signaling pathway. Furthermore, transgenic tobacco plants with elevated GABA levels were less sensitive to A. tumefaciens C58 infection than were wild-type plants. These findings indicate that plant GABA may modulate quorum sensing in A. tumefaciens, thereby affecting its virulence on plants. Whereas GABA is an essential cell-to-cell signal in eukaryotes, here we provide evidence of GABA acting as a signal between eukaryotes and pathogenic bacteria. The GABA signal represents a potential target for the development of a strategy to control the virulence of bacterial pathogens.
Chevrot
Romain
R
Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Avenue de la Terrasse, Gif-sur-Yvette 91 198, France.
Rosen
Ran
R
Haudecoeur
Elise
E
Cirou
Amélie
A
Shelp
Barry J
BJ
Ron
Eliora
E
Faure
Denis
D
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D000098:Acetophenones / Q000494:pharmacology; D016960:Agrobacterium tumefaciens / Q000187:drug effects* / Q000378:metabolism* / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D009876:Operon / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D005680:gamma-Aminobutyric Acid / Q000737:chemistry / Q000494:pharmacology*
D000098:Acetophenones; D001426:Bacterial Proteins; C511789:N-(3-oxooctanoyl)homoserine lactone; D005680:gamma-Aminobutyric Acid; C051667:acetosyringone; D005968:Glutamate Decarboxylase; D015107:4-Butyrolactone