Non-ribosomal Peptide Synthases from Pseudomonas aeruginosa Play a Role in Cyclodipeptide Biosynthesis, Quorum-Sensing Regulation, and Root Development in a Plant Host

• Published in: Microbial ecology Vol. 73; no. 3; pp. 616 - 629
• Main Authors: Gonzalez, Omar, Ortiz-Castro, Randy, Diaz-Perez, Cesar, Diaz-Perez, Alma L, Magana-Duenas, Viridiana, Lopez-Bucio, Jose, Campos-Garcia, Jesus
• Format: Journal Article
• Language: English
• Published: New York Springer Science + Business Media 01-04-2017; Springer US; Springer Nature B.V
• Subjects: Arabidopsis - microbiology; Arabidopsis thaliana; Bioinformatics; Biomedical and Life Sciences; Biosynthesis; Dipeptides - genetics; Dipeptides - metabolism; Ecology; Gene Expression Regulation, Bacterial - genetics; Genetics; Geoecology/Natural Processes; Indoleacetic Acids - metabolism; Indoles - metabolism; Life Sciences; Microbial Ecology; Microbiology; Nature Conservation; Peptide Biosynthesis, Nucleic Acid-Independent - genetics; Peptides, Cyclic - genetics; Peptides, Cyclic - metabolism; Piperazines - metabolism; Plant growth; PLANT MICROBE INTERACTIONS; Plant Roots - embryology; Pseudomonas aeruginosa; Pseudomonas aeruginosa - enzymology; Pseudomonas aeruginosa - genetics; Pseudomonas aeruginosa - metabolism; Pyocyanine - metabolism; Quorum Sensing - genetics; Quorum Sensing - physiology; Root development; Seedlings; Signal Transduction; Virulence Factors - metabolism; Water Quality/Water Pollution; Siderophores; Cyclodipeptides; Quorum-sensing; Non-ribosomal peptide synthases; Plant-growth promotion; Pseudomonas aeruginosa
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-016-0896-4

Diverse molecules mediate cross-kingdom communication between bacteria and their eukaryotic partners and determine pathogenic or symbiotic relationships. N-acyl-L-homoserine lactone-dependent quorum-sensing signaling represses the biosynthesis of bacterial cyclodipeptides (CDPs) that act as auxin signal mimics in the host plant Arabidopsis thaliana. In this work, we performed bioinformatics, biochemical, and plant growth analyses to identify nonribosomal peptide synthase (NRPS) proteins of Pseudomonas aeruginosa, which are involved in CDP synthesis. A reverse genetics strategy allowed the identification of the genes encoding putative multi-modular-NRPS (MM-NRPS). Mutations in these genes affected the synthesis of the CDPs cyclo (L-Pro-L-Val), cyclo (L-Pro-L-Leu), and cyclo (L-Pro-L-Tyr), while showing wild-type-like levels of virulence factors, such as violacein, elastase, and pyocyanin. When analyzing the bioactivity of purified, naturally produced CDPs, it was found that cyclo (L-Pro-L-Tyr) and cyclo (L-Pro-L-Val) were capable of antagonizing quorum-sensing-LasR (QS-LasR)-dependent signaling in a contrasting manner in the cell-free supernatants of the selected NRPS mutants, which showed QS induction. Using a bacteria-plant interaction system, we further show that the pvdJ, ambB, and pchE P. aeruginosa mutants failed to repress primary root growth, but improved root branching in A. thaliana seedlings. These results indicated that the CDP production in P. aeruginosa depended on the functional MM-NRPS, which influences quorum-sensing of bacteria and plays a role in root architecture remodeling.