Dataset Information

Characterization of CorR, a transcriptional activator which is required for biosynthesis of the phytotoxin coronatine.

ABSTRACT: Coronatine (COR) is a plasmid-encoded phytotoxin synthesized by several pathovars of phytopathogenic Pseudomonas syringae. The COR biosynthetic gene cluster in P. syringae pv. glycinea PG4180 is encoded by a 32-kb region which contains both the structural and regulatory genes needed for COR synthesis. The regulatory region contains three genes: corP, corS, and corR. corS is thought to function as a histidine protein kinase, whereas corP and corR show relatedness to response regulators of the two-component regulatory paradigm. In the present study, we investigated whether CorR is a positive activator of COR gene expression. We also studied whether CorR specifically binds the DNA region located upstream of cfl, a gene located at the 5' end of the gene cluster encoding coronafacic acid, the polyketide portion of COR. Complementation analysis with a corR mutant, PG4180.P2, and transcriptional fusions to a promoterless glucuronidase gene (uidA) indicated that CorR functions as a positive regulator of COR gene expression. Deletion analysis of the 5' end of the cfl upstream region was used to define the minimal region required for COR gene expression. A 360-bp DNA fragment located over 500 bp upstream from the cfl transcriptional start site was used in DNase I protection assays to define the specific bases bound by CorR. An area extending from -704 to -650 with respect to the cfl transcriptional start site was protected by DNase I footprinting, indicating a rather large area of protection. This area was also conserved in the promoter region for cmaA, which encodes a transcript containing genes for coronamic acid synthesis, another intermediate in the COR biosynthetic pathway. The results obtained in the current study suggest that both the coronafacic acid and the coronamic acid structural genes are controlled by CorR, a positive activator of COR gene expression.

SUBMITTER: Penaloza-Vazquez A

PROVIDER: S-EPMC107710 | biostudies-literature | 1998 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Characterization of CorR, a transcriptional activator which is required for biosynthesis of the phytotoxin coronatine.

Peñaloza-Vázquez A A Bender C L CL

Journal of bacteriology 19981201 23

Coronatine (COR) is a plasmid-encoded phytotoxin synthesized by several pathovars of phytopathogenic Pseudomonas syringae. The COR biosynthetic gene cluster in P. syringae pv. glycinea PG4180 is encoded by a 32-kb region which contains both the structural and regulatory genes needed for COR synthesis. The regulatory region contains three genes: corP, corS, and corR. corS is thought to function as a histidine protein kinase, whereas corP and corR show relatedness to response regulators of the two ...[more]

PMID: 9829934

Similar Datasets

Project description:Coronafacoyl phytotoxins are an important family of plant toxins that are produced by several different phytopathogenic bacteria, including the gammaproteobacterium Pseudomonas syringae and the actinobacterium Streptomyces scabiei (formerly Streptomyces scabies). The phytotoxins consist of coronafacic acid (CFA) linked via an amide bond to different amino acids or amino acid derivatives. Previous work suggested that S. scabiei and P. syringae use distinct biosynthetic pathways for producing CFA, which is subsequently linked to its amino acid partner to form the complete phytotoxin. Here, we provide further evidence that the S. scabiei CFA biosynthetic pathway is novel by characterizing the role of CYP107AK1, a predicted cytochrome P450 that has no homologue in P. syringae Deletion of the CYP107AK1 gene abolished production of coronafacoyl-isoleucine (CFA-Ile), the primary coronafacoyl phytotoxin produced by S. scabiei Structural elucidation of accumulated biosynthetic intermediates in the ΔCYP107AK1 mutant indicated that CYP107AK1 is required for introducing the oxygen atom that ultimately forms the carbonyl group in the CFA backbone. The CYP107AK1 gene along with two additional genes involved in CFA-Ile biosynthesis in S. scabiei were found to be associated with putative CFA biosynthetic genes in other actinobacteria but not in other organisms. Analysis of the overall genetic content and organization of known and putative CFA biosynthetic gene clusters, together with phylogenetic analysis of the core biosynthetic genes, indicates that horizontal gene transfer has played an important role in the dissemination of the gene cluster and that rearrangement, insertion, and/or deletion events have likely contributed to the divergent biosynthetic evolution of coronafacoyl phytotoxins in bacteria.IMPORTANCE The ability of plants to defend themselves against invading pathogens relies on complex signaling pathways that are controlled by key phytohormones such as jasmonic acid (JA). Some phytopathogenic bacteria have evolved the ability to manipulate JA signaling in order to overcome host defenses by producing coronatine (COR), which functions as a potent JA mimic. COR and COR-like molecules, collectively referred to as coronafacoyl phytotoxins, are produced by several different plant-pathogenic bacteria, and this study provides supporting evidence that different biosynthetic pathways are utilized by different bacteria for production of these phytotoxins. In addition, our study provides a greater understanding of how coronafacoyl phytotoxin biosynthesis may have evolved in phylogenetically distinct bacteria, and we demonstrate that production of these compounds may be more widespread than previously recognized and that their role for the producing organism may not be limited to host-pathogen interactions.

Dataset Information

Characterization of CorR, a transcriptional activator which is required for biosynthesis of the phytotoxin coronatine.

Publications

Characterization of CorR, a transcriptional activator which is required for biosynthesis of the phytotoxin coronatine.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets