Location: Emerging Pests and Pathogens ResearchTitle: Prevention of surface-associated calcium phosphate by the Pseudomonas syringae two-component system CvsSR
|FISHMAN, MAX - Cornell University|
Submitted to: Journal of Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2019
Publication Date: 1/7/2019
Citation: Fishman, M., Filiatrault, M.J. 2019. Prevention of surface-associated calcium phosphate by the Pseudomonas syringae two-component system CvsSR. Journal of Bacteriology. 201(7). https://doi.org/10.1128/JB.00584-18.
Interpretive Summary: Calcium signaling is important in the recognition of microbes in plants and the plant defense response. We previously reported the characterization of a bacterial signaling system in the plant-pathogenic bacterium P. syringae that responds to the presence of calcium and is important for causing disease. Here we discovered that this signaling system controls the ability of the bacterium to prevent calcium precipitate accumulation on the surface of the bacterial cells. Furthermore we demonstrate that the ability of the bacterium to move is controlled by the formation and dissolution of calcium precipitates on the surface of bacterial cells. The results provide a better understanding of how bacteria translate signals from the host and coordinate factors necessary for causing disease. The discovery is expected to provide a target for developing methods to control bacterial plant pathogens.
Technical Abstract: CvsSR is a Ca2+-induced two-component system (TCS) in the plant pathogen Pseudomonas syringae pv. tomato DC3000 (Pto). Here we discovered CvsSR is induced by Fe3+, Zn2+, and Cd2+. However, only supplementation of Ca2+ to medium resulted in rugose, opaque colonies in deltacvsS and deltacvsR strains. This phenotype corresponded to formation of calcium phosphate precipitation on the surface of deltacvsS and deltacvsR colonies. CvsSR regulated swarming motility in Pto in a Ca2+-dependent manner, but swarming behavior was not influenced by Fe3+, Zn2+, or Cd2+. We hypothesized that reduced swarming displayed by deltacvsS and deltacvsR was due to precipitation of calcium phosphate on the surface of deltacvsS and deltacvsR grown on agar medium supplemented with Ca2+. By reducing the initial pH or adding glucose to the medium, calcium precipitation was inhibited and swarming was restored to deltacvsS and deltacvsR, suggesting calcium precipitation influences swarming ability. Constitutive expression a CvsSR regulated carbonic anhydrase and a CvsSR regulated putative sulfate major facilitator superfamily transporter in deltacvsS and deltacvsR inhibited formation of calcium precipitates and restored the ability of deltacvsS and deltacvsR to swarm. Lastly, we found that glucose inhibited Ca2+ -based induction of CvsSR. Hence, CvsSR is a key regulator that controls calcium precipitation on the surface of bacterial cells.