Control of temperature-responsive synthesis of the phytotoxin coronatine in Pseudomonas syringae by the unconventional two-component system CorRPS.
J Mol Microbiol Biotechnol
; 4(3): 191-6, 2002 May.
Article
en En
| MEDLINE
| ID: mdl-11931546
ABSTRACT
The phytopathogen Pseudomonas syringae produces the phytotoxin coronatine (COR) as a major virulence factor. COR and its precursor, coronafacic acid, function as molecular mimics of the plant signaling molecule jasmonate. A 32.8-kb plasmid-borne gene cluster mediates COR biosynthesis, which is optimal at 18 degrees C and non-detectable at 28 degrees C, the optimal growth temperature for P. syringae. The thermoregulation is mediated at the transcriptional level by an unconventional two-component regulatory system consisting of a histidine protein kinase, CorS, and two transcriptional activators, CorR and CorP. Dissection of this regulatory triad revealed that CorR binds to its target sequences in a thermoresponsive manner and that its DNA-binding activity is controlled by CorS. A Preliminary model for thermo-sensing by CorS is proposed based on its membrane topology and the analysis of translational fusions of CorS to reporter enzymes at different temperatures. CorP lacks a typical helix-turn-helix motif but possibly functions as a modulator of CorR or CorS activity. The thermoregulation of COR biosynthetic genes is widespread among various COR-producing P. syringae strains. Post-translational processes also contribute to the thermo-responsiveness of COR production. Additionally, COR synthesis in P. syringae is influenced by nutrient availability, rpoN encoding the alternative sigma factor sigma54, and HrpV, a negative regulator of hrp gene expression, suggesting a complex regulatory network governing phytotoxin synthesis.
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Banco de datos:
MEDLINE
Asunto principal:
Pseudomonas
/
Proteínas Bacterianas
/
Toxinas Bacterianas
/
Regulación Bacteriana de la Expresión Génica
/
Transactivadores
/
Aminoácidos
Tipo de estudio:
Prognostic_studies
Idioma:
En
Año:
2002
Tipo del documento:
Article