Plant growth-promoting Pseudomonas putida WCs358 produces and secretes four cyclic dipeptides: Cross-talk with quorum sensing bacterial sensors

• Published in: Current microbiology Vol. 45; no. 4; pp. 250 - 254
• Main Authors: DEGRASSI, Giuliano, AGUILAR, Claudio, BOSCO, Marco, ZAHARIEV, Sotir, PONGOR, Sandor, VENTURI, Vittorio
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01.10.2002; Springer Nature B.V
• Subjects: 4-Butyrolactone - analogs & derivatives; 4-Butyrolactone - metabolism; Bacteria; Bacteriology; Biological and medical sciences; Biosensing Techniques; Biosensors; Cell Communication; Culture Media; Dipeptides - chemistry; Dipeptides - isolation & purification; Dipeptides - secretion; Escherichia coli - genetics; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Genetics; Gram-negative bacteria; Liquid chromatography; Microbiology; Models, Molecular; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Peptides, Cyclic - chemistry; Peptides, Cyclic - isolation & purification; Peptides, Cyclic - secretion; Phenotype; Plant Development; Plant growth; Plants - drug effects; Pseudomonas putida; Pseudomonas putida - metabolism; Pseudomonas putida - physiology; Signal Transduction; Pseudomonadales; Characterization; Signal transduction; Purification; Cyclic compound; Virulence; Dipeptides; Bacteria; Pseudomonadaceae; Lactone; Detection; Pseudomonas putida
• ISSN: 0343-8651; 1432-0991
• DOI: 10.1007/s00284-002-3704-y

The most universal cell-cell signaling mechanism in Gram-negative bacteria occurs via the production and response to a class of small diffusible molecules called N-acylhomoserine lactones (AHLs). This communication is called quorum sensing and is responsible for the regulation of several physiological processes and many virulence factors in pathogenic bacteria. The detection of these molecules has been rendered possible by the utilization of genetically engineered bacterial biosensors which respond to the presence of exogenously supplied AHLs. In this study, using diverse bacterial biosensors, several biosensor activating fractions were purified by organic extraction, HPLC and TLC of cell-free culture supernatants of plant growth-promoting Pseudomonas putida WCS358. Surprisingly, it was observed that the most abundant compounds in these fractions were cyclic dipeptides (diketopiperazines, DKPs), a rather novel finding in Gram-negative bacteria. The purification, characterization, chemical synthesis of four DKPs are reported and their possible role in cell-cell signaling is discussed.