Component and protein domain exchange analysis of a thermoresponsive, two-component regulatory system of Pseudomonas syringae

Abstract

Two closely related phytopathogenic bacterial strains, Pseudomonas syringae pv. glycinea PG4180 and P. syringae pv. tomato DC3000, produce the chlorosis-inducing phytotoxin coronatine (COR) in a remarkably divergent manner. PG4180 produces COR at the virulencepromoting temperature of 18 6C, but not at 28 6C. In contrast, temperature has no effect on COR synthesis in DC3000. A modified two-component system consisting of the histidine protein kinase (HPK), CorS, the response regulator (RR), CorR, and a third component, CorP, governs COR biosynthesis in both strains. A plasmid-based component and domain swapping approach was used to introduce different combinations of RRs, HPKs and hybrid HPKs into corS mutants of both strains. Subsequently, expression levels of the COR biosynthetic cma operon were determined using RNA dot-blot analysis, suggesting that CorRSP of PG4180 mediates a thermoresponsive phenotype dependent on the genomic background of each strain. The reciprocal experiment demonstrated a loss of temperature dependence in the corS mutant of PG4180. The presence of corR from PG4180 led to more pronounced cma expression in DC3000 and was associated with thermoresponsiveness, while corS of PG4180 did not mediate a temperature-dependent phenotype in the DC3000 mutant containing native corR and corP. These findings were substantiated by RT-PCR experiments. The C-terminal domain of CorS of PG4180 mediated thermosensing, while the N terminus did not respond to temperature changes, suggesting cytosolic perception of the temperature signal.

Temperature-responsive sensing regulates biocontrol factor expression in Pseudomonas fluorescens CHA0

“…This thermoregulation is mediated at the transcriptional level by a regulatory system consisting of a histidine protein kinase, CorS, and two transcriptional activators, CorR and CorP. The C-terminal cytosolic region of CorS appears to act as a temperature sensor; it is believed to respond to intracellular temperature changes via autophosphorylation and to transduce the signal to the response regulator CorR via phosphorylation (Braun et al, 2008). Another example is provided by the thermal control of fatty acid synthesis.…”

Characterization of a Ferrous Iron-Responsive Two-Component System in Nontypeable Haemophilus influenzae

“…Cold temperatures affect the TCST systems CorRS and DesKR in Pseudomonas syringae and Bacillus subtilis, respectively (1,10). Therefore, we tested whether expression of the ygiW-firRS operon was affected when exponentially grown wild-type 2019 cultures were exposed to cold temperatures.…”

The CasKR Two-Component System Is Required for the Growth of Mesophilic and Psychrotolerant Bacillus cereus Strains at Low Temperatures

“…In a Gram-negative bacterium, the CheA/ CheY 2CS mutant of Yersinia pseudotuberculosis was impaired during growth at 3°C (22). 2CSs of other Gram-negative bacteria have been described to be temperature sensors for bacterial virulence control, such as CorSR in Pseudomonas (23) and PhoPQ in Edwardsiella (24). Recent research has revealed how a 2CS contributes to the high adaptability of B. cereus strains that enables these bacteria to persist in processed foods (25).…”