Donald A. Cooksey

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Copper-resistant strains of Pseudomonas syringae pathovar tomato accumulate copper and develop blue colonies on copper-containing media. Three of the protein products of the copper-resistance operon (cop) were characterized to provide an understanding of the copper-resistance mechanism and its relationship to copper accumulation. The Cop proteins, CopA (72(More)
Pseudomonads from environmental sources vary widely in their sensitivity to cadmium, but the basis for this resistance is largely uncharacterized. A chromosomal fragment encoding cadmium resistance was cloned from Pseudomonas putida 06909, a rhizosphere bacterium, and sequence analysis revealed two divergently transcribed genes, cadA and cadR. CadA was(More)
Twenty strains of Pseudomonas syringae pv. tomato were examined for the presence of plasmid DNA. P. syringae pv. tomato plasmids were grouped into five size classes: class A ranged from 95 to 103 kilobases (kb); class B ranged from 71 to 83 kb; class C ranged from 59 to 67 kb; class D ranged from 37 to 39 kb; and class E was 29 kb. All strains contained at(More)
An unusual mechanism of metal resistance is found in certain plant pathogenic strains of Pseudomonas syringae that are exposed to high levels of copper compounds used in disease control on agricultural crops. These bacteria accumulate blue Cu2+ ions in the periplasm and outer membrane. At least part of this copper sequestering activity is determined by(More)
The nucleotide sequence of a 4.5-kilobase copper resistance determinant from Pseudomonas syringae pv. tomato revealed four open reading frames (ORFs) in the same orientation. Deletion and site-specific mutational analyses indicated that the first two ORFs were essential for copper resistance; the last two ORFs were required for full resistance, but(More)
Copper-resistant strains of Xanthomonas campestris pv. vesicatoria, Pseudomonas cichorii, Pseudomonas putida, Pseudomonas fluorescens, and a yellow Pseudomonas sp. were isolated from tomato plants or seeds. In Southern hybridizations, DNA from each strain showed homology with the copper resistance (cop) operon previously cloned from Pseudomonas syringae pv.(More)
Production of the plant hormone indole-3-acetic acid (IAA) is widespread among plant-associated microorganisms. The non-gall-forming phytopathogen Erwinia chrysanthemi 3937 (strain Ech3937) possesses iaaM (ASAP16562) and iaaH (ASAP16563) gene homologues. In this work, the null knockout iaaM mutant strain Ech138 was constructed. The IAA production by Ech138(More)
Copper-resistant strains of Pseudomonas syringae carrying the cop operon produce periplasmic copper-binding proteins, and this sequestration outside the cytoplasm has been proposed as a resistance mechanism. In this study, strain PS61 of P. syringae carrying the cloned cop operon accumulated more total cellular copper than without the operon. Several other(More)
Avirulence gene D (avrD) in strain PT23 of Pseudomonas syringae pv. tomato (Pst) specifies the production of syringolides, which are elicitors of plant defense reactions. An 83-kb indigenous plasmid (pPT23B) that carries avrD has been mapped and characterized and a putative par region was identified. pPT23B contains a large amount of DNA that is repeated in(More)
Plasmid-borne copper resistance genes from copper-resistant strains of Xanthomonas campestris pv. vesicatoria from California, Florida, and Oklahoma shared structural similarities. A strain of X. campestris pv. campestris also contained plasmid-borne copper resistance genes similar to the resistance genes from X. campestris pv. vesicatoria. Furthermore, a(More)