Dataset Information

A modified two-component regulatory system is involved in temperature-dependent biosynthesis of the Pseudomonas syringae phytotoxin coronatine.

ABSTRACT: Biosynthesis of the phytotoxin coronatine (COR) in Pseudomonas syringae pv. glycinea PG4180 is regulated by temperature at the transcriptional level. A 3.4-kb DNA fragment from the COR biosynthetic gene cluster restored temperature-regulated phytotoxin production to Tn5 mutants defective in COR production. Nucleotide sequence analysis of this fragment revealed three genes, corS, corP, and corR, which encode a modified two-component regulatory system consisting of one sensor protein, CorS, and two response regulator proteins, CorP and CorR. Although only one response regulator, CorR, had a DNA-binding domain, the phosphate-receiving domains of both response regulator proteins were highly conserved. Transcriptional fusions of the corP and corR promoters to a promoterless glucuronidase gene (uidA) indicated that these two genes are expressed constitutively at 18 and 28 degrees C. In contrast, a corS::uidA fusion exhibited the temperature dependence previously observed for COR biosynthetic promoters and exhibited maximal transcriptional activity at 18 degrees C and low activity at 28 degrees C. Furthermore, glucuronidase activity for corS::uidA was decreased in corP, corR, and corS mutants relative to the levels observed for PG4180(corS::uidA). This difference was not observed for corP::uidA and corR::uidA transcriptional fusions since expression of these fusions remained low and constitutive regardless of the genetic background. The three regulatory genes functioned in a P. syringae strain lacking the COR gene cluster to achieve temperature-dependent activation of an introduced COR biosynthetic promoter, indicating that this triad of genes is the primary control for COR biosynthesis and responsible for thermoregulation. Our data suggest that the modified two-component regulatory system described in this study might transduce and amplify a temperature signal which results in transcriptional activation of COR biosynthetic genes.

SUBMITTER: Ullrich M

PROVIDER: S-EPMC177456 | biostudies-other | 1995 Nov

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

A modified two-component regulatory system is involved in temperature-dependent biosynthesis of the Pseudomonas syringae phytotoxin coronatine.

Ullrich M M Peñaloza-Vázquez A A Bailey A M AM Bender C L CL

Journal of bacteriology 19951101 21

Biosynthesis of the phytotoxin coronatine (COR) in Pseudomonas syringae pv. glycinea PG4180 is regulated by temperature at the transcriptional level. A 3.4-kb DNA fragment from the COR biosynthetic gene cluster restored temperature-regulated phytotoxin production to Tn5 mutants defective in COR production. Nucleotide sequence analysis of this fragment revealed three genes, corS, corP, and corR, which encode a modified two-component regulatory system consisting of one sensor protein, CorS, and tw ...[more]

PMID: 7592381

Similar Datasets

Project description:CvsSR is a Ca2+-induced two-component system (TCS) in the plant pathogen Pseudomonas syringae pv. tomato DC3000. Here, we discovered that CvsSR is induced by Fe3+, Zn2+, and Cd2+ However, only supplementation of Ca2+ to medium resulted in rugose, opaque colonies in ΔcvsS and ΔcvsR strains. This phenotype corresponded to formation of calcium phosphate precipitation on the surface of ΔcvsS and ΔcvsR colonies. CvsSR regulated swarming motility in P. syringae pv. tomato in a Ca2+-dependent manner, but swarming behavior was not influenced by Fe3+, Zn2+, or Cd2+ We hypothesized that reduced swarming displayed by ΔcvsS and ΔcvsR strains was due to precipitation of calcium phosphate on the surface of ΔcvsS and ΔcvsR cells 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 ΔcvsS and ΔcvsR strains, suggesting that calcium precipitation influences swarming ability. Constitutive expression of a CvsSR-regulated carbonic anhydrase and a CvsSR-regulated putative sulfate major facilitator superfamily transporter in ΔcvsS and ΔcvsR strains inhibited formation of calcium precipitates and restored the ability of ΔcvsS and ΔcvsR bacteria 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.IMPORTANCE Bacteria are capable of precipitating and dissolving minerals. We previously reported the characterization of the two-component system CvsSR in the plant-pathogenic bacterium Pseudomonas syringae CvsSR responds to the presence of calcium and is important for causing disease. Here, we show that CvsSR controls the ability of the bacterium to prevent calcium phosphate precipitation on the surface of cells. We also identified a carbonic anhydrase and transporter that modulate formation of surface-associated calcium precipitates. Furthermore, our results demonstrate that the ability of the bacterium to swarm is controlled by the formation and dissolution of calcium precipitates on the surface of cells. Our study describes new mechanisms for microbially induced mineralization and provides insights into the role of mineral deposits on bacterial physiology. The discoveries may lead to new technological and environmental applications.

Project description:The glycopeptide A40926, produced by the actinomycete Nonomuraea gerenzanensis, is the precursor of dalbavancin, a second-generation glycopeptide antibiotic approved for clinical use in the USA and Europe in 2014 and 2015, respectively. The final product of the biosynthetic pathway is an O-acetylated form of A40926 (acA40926). Glycopeptide biosynthesis in N. gerenzanensis is dependent upon the dbv gene cluster that encodes, in addition to the two essential positive regulators Dbv3 and Dbv4, the putative members of a two-component signal transduction system, specifically the response regulator Dbv6 and the sensor kinase Dbv22. The aim of this work was to assign a role to these two genes. Our results demonstrate that deletion of dbv22 leads to an increased antibiotic production with a concomitant reduction in glycopeptide resistance. Deletion of dbv6 results in a similar phenotype, although the effects are not as strong as in the Δdbv22 mutant. Consistently, quantitative RT-PCR analysis showed that Dbv6 and Dbv22 negatively regulate the regulatory genes (dbv3 and dbv4), as well as some dbv biosynthetic genes (dbv23 and dbv24), whereas Dbv6 and Dbv22 positively regulate transcription of the single, cluster-associated resistance gene. Finally, we demonstrate that exogenously added acA40926 and its precursor A40926 can modulate transcription of dbv genes but with an opposite extent: A40926 strongly stimulates transcription of the Dbv6/Dbv22 target genes while acA40926 has a neutral or negative effect on transcription of those genes. We propose a model in which glycopeptide biosynthesis in N. gerenzanensis is modulated through a positive feedback by the biosynthetic precursor A40926 and a negative feedback by the final product acA40926. In addition to previously reported control systems, this sophisticated control loop might help the producing strain cope with the toxicity of its own product. This work, besides leading to improved glycopeptide producing strains, enlarges our knowledge on the regulation of glycopeptide biosynthesis in actinomycetes, setting N. gerenzanensis and its two-component system Dbv6-Dbv22 apart from other glycopeptide producers.

Dataset Information

A modified two-component regulatory system is involved in temperature-dependent biosynthesis of the Pseudomonas syringae phytotoxin coronatine.

Publications

A modified two-component regulatory system is involved in temperature-dependent biosynthesis of the Pseudomonas syringae phytotoxin coronatine.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets