title: Rhizoxin analogs, orfamide A and chitinase production contribute to the toxicity of Pseudomonas protegens strain Pf-5 to Drosophila melanogaster.
abstract: Pseudomonas protegens strain Pf-5 is a soil bacterium that was first described for its capacity to suppress plant diseases and has since been shown to be lethal to certain insects. Among these is the common fruit fly Drosophila melanogaster, a well-established model organism for studies evaluating the molecular and cellular basis of the immune response to bacterial challenge. Pf-5 produces the insect toxin FitD, but a ΔfitD mutant of Pf-5 retained full toxicity against D. melanogaster in a noninvasive feeding assay, indicating that FitD is not a major determinant of Pf-5's oral toxicity against this insect. Pf-5 also produces a broad spectrum of exoenzymes and natural products with antibiotic activity, whereas a mutant with a deletion in the global regulatory gene gacA produces none of these exoproducts and also lacks toxicity to D. melanogaster. In this study, we made use of a panel of Pf-5 mutants having single or multiple mutations in the biosynthetic gene clusters for seven natural products and two exoenzymes that are produced by the bacterium under the control of gacA. Our results demonstrate that the production of rhizoxin analogs, orfamide A, and chitinase are required for full oral toxicity of Pf-5 against D. melanogaster, with rhizoxins being the primary determinant.
authors.affiliation: Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Ave., Corvallis, OR, 97330, USA. loperj@science.oregonstate.edu.|Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA. loperj@science.oregonstate.edu.
authors.forename: Joyce E
authors.initials: JE
authors.lastname: Loper
authors.affiliation: Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Ave., Corvallis, OR, 97330, USA.|Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Marcella D
authors.initials: MD
authors.lastname: Henkels
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Lorena I
authors.initials: LI
authors.lastname: Rangel
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Marika H
authors.initials: MH
authors.lastname: Olcott
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Francesca L
authors.initials: FL
authors.lastname: Walker
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Kise L
authors.initials: KL
authors.lastname: Bond
authors.affiliation: Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Ave., Corvallis, OR, 97330, USA.|Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Kidarsa
authors.affiliation: Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Ave., Corvallis, OR, 97330, USA.
authors.forename: Cedar N
authors.initials: CN
authors.lastname: Hesse
authors.affiliation: Department of Molecular Biology and Ecology of Plants, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Baruch
authors.initials: B
authors.lastname: Sneh
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Virginia O
authors.initials: VO
authors.lastname: Stockwell
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Taylor
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002688:Chitinases / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000382:microbiology*; D005809:Genes, Regulator; D055666:Lipopeptides / Q000378:metabolism* / Q000633:toxicity; D009154:Mutation; D010456:Peptides, Cyclic / Q000378:metabolism* / Q000633:toxicity; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D055666:Lipopeptides; D010456:Peptides, Cyclic; C585331:orfamide A; D002688:Chitinases