ppGpp controlled by the Gac/Rsm regulatory pathway sustains biocontrol activity in Pseudomonas fluorescens CHA0.

Détails

ID Serval
serval:BIB_C8FF33DED1AB
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
ppGpp controlled by the Gac/Rsm regulatory pathway sustains biocontrol activity in Pseudomonas fluorescens CHA0.
Périodique
Molecular Plant-microbe Interactions
Auteur(s)
Takeuchi K., Yamada K., Haas D.
ISSN
0894-0282 (Print)
ISSN-L
0894-0282
Statut éditorial
Publié
Date de publication
2012
Volume
25
Numéro
11
Pages
1440-1449
Langue
anglais
Résumé
In Pseudomonas fluorescens CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway is instrumental for secondary metabolism and biocontrol of root pathogens via the expression of regulatory small RNAs (sRNAs). Furthermore, in strain CHA0, an imbalance in the Krebs cycle can affect the strain's ability to produce extracellular secondary metabolites, including biocontrol factors. Here, we report the metabolome of wild-type CHA0, a gacA-negative mutant, which has lost Gac/Rsm activities, and a retS-negative mutant, which shows strongly enhanced Gac/Rsm-dependent activities. Capillary electrophoresis-based metabolomic profiling revealed that the gacA and retS mutations had opposite effects on the intracellular levels of a number of central metabolites, suggesting that the Gac/Rsm pathway regulates not only secondary metabolism but also primary metabolism in strain CHA0. Among the regulated metabolites identified, the alarmone guanosine tetraphosphate (ppGpp) was characterized in detail by the construction of relA (for ppGpp synthase) and spoT (for ppGpp synthase/hydrolase) deletion mutants. In a relA spoT double mutant, ppGpp synthesis was completely abolished, the expression of Rsm sRNAs was attenuated, and physiological functions such as antibiotic production, root colonization, and plant protection were markedly diminished. Thus, ppGpp appears to be essential for sustaining epiphytic fitness and biocontrol activity of strain CHA0.
Mots-clé
Cucumis sativus/microbiology, Electrophoresis, Capillary, Gene Expression Regulation, Bacterial, Guanosine Tetraphosphate/metabolism, Pseudomonas fluorescens/genetics, Pseudomonas fluorescens/metabolism
Pubmed
Web of science
Création de la notice
15/11/2012 19:22
Dernière modification de la notice
03/03/2018 21:22
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