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PMID:18487321

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Citation

Studer, SV, Mandel, MJ and Ruby, EG (2008) AinS quorum sensing regulates the Vibrio fischeri acetate switch. J. Bacteriol. 190:5915-23

Abstract

The marine bacterium Vibrio fischeri uses two acyl-homoserine lactone (acyl-HSL) quorum-sensing systems. The earlier signal, octanoyl-HSL, produced by AinS, is required for normal colonization of the squid Euprymna scolopes and, in culture, is necessary for a normal growth yield. In examining the latter requirement, we found that during growth in a glycerol/tryptone-based medium, wild-type V. fischeri cells initially excrete acetate but, in a metabolic shift termed the acetate switch, they subsequently utilize the acetate, removing it from the medium. In contrast, an ainS mutant strain grown in this medium does not remove the excreted acetate, which accumulates to lethal levels. The acetate switch is characterized by the induction of acs, the gene encoding acetyl coenzyme A (acetyl-CoA) synthetase, leading to uptake of the excreted acetate. Wild-type cells induce an acs transcriptional reporter 25-fold, coincident with the disappearance of the extracellular acetate; in contrast, the ainS mutant did not display significant induction of the acs reporter. Supplementation of the medium of an ainS mutant with octanoyl-HSL restored normal levels of acs induction and acetate uptake. Additional mutant analyses indicated that acs regulation was accomplished through the regulator LitR but was independent of the LuxIR quorum-signaling pathway. Importantly, the acs mutant of V. fischeri has a competitive defect when colonizing the squid, indicating the importance of proper control of acetate metabolism in the light of organ symbiosis. This is the first report of quorum-sensing control of the acetate switch, and it indicates a metabolic connection between acetate utilization and cell density.

Links

PubMed PMC2519518 Online version:10.1128/JB.00148-08

Keywords

Acetate-CoA Ligase/genetics; Acetate-CoA Ligase/metabolism; Acetates/metabolism; Acyl-Butyrolactones/metabolism; Aliivibrio fischeri/genetics; Aliivibrio fischeri/growth & development; Aliivibrio fischeri/metabolism; Animals; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacterial Proteins/physiology; Chromatography, High Pressure Liquid; Decapodiformes/microbiology; Gene Expression Regulation, Bacterial/drug effects; Glucose/pharmacology; Models, Biological; Mutation; Quorum Sensing; Repressor Proteins/genetics; Repressor Proteins/metabolism; Repressor Proteins/physiology; Trans-Activators/genetics; Trans-Activators/metabolism; Trans-Activators/physiology

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

VIBF1:Q5E614

GO:0016747: transferase activity, transferring acyl groups other than amino-acyl groups

ECO:0000315:

F

Figure 1 shows the AinS signaling cascade that controls the Lux operon.

complete
CACAO 9601

VIBF1:Q5E268

GO:0006083: acetate metabolic process

ECO:0000315:

P

Fig 5, Table 2

complete
CACAO 11472

See also

References

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