Control of temperature-responsive synthesis of the phytotoxin coronatine in Pseudomonas syringae by the unconventional two-component system CorRPS.
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.
Smirnova
Angela V
AV
Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany.
Wang
Ling
L
Rohde
Bettina
B
Budde
Ina
I
Weingart
Helge
H
Ullrich
Matthias S
MS
D000596:Amino Acids / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007192:Indenes; D005810:Multigene Family; D010935:Plant Diseases / Q000382:microbiology; D011549:Pseudomonas / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013696:Temperature; D015534:Trans-Activators
D000596:Amino Acids; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C096449:CorP protein, Pseudomonas syringae; C096450:CorR protein, Pseudomonas syringae; C096448:CorS protein, Pseudomonas syringae; D004268:DNA-Binding Proteins; D007192:Indenes; D015534:Trans-Activators; C058487:coronatine