title: AHL signals induce rubrifacine production in a bruI mutant of Brenneria rubrifaciens.
abstract: Several members of the bacterial genus Brenneria are pathogenic on different tree species. Cell-free extracts from the bacterial phytopathogens Brenneria rubrifaciens, B. salicis, and B. nigrifluens induced production of the red pigment rubrifacine in the B. rubrifaciens bruI insertional mutant Br-212. Analysis of the bruI locus identified an adjacent open reading frame, designated bruR, with homology to luxR. High-performance liquid chromatography and mass spectrometry analysis of ethyl acetate extracts from wild-type B. rubrifaciens and Escherichia coli expressing the bruI gene identified two acyl homoserine lactone (AHL) peaks, N-(3-oxohexanoyl)-homoserine lactone (3OC6HSL) and N-hexanoyl-homoserine lactone (C6HSL). Addition of synthetic 3OC6HSL and C6HSL at 10 μM to the bruI mutant, strain Br-212, induced rubrifacine production and the ability to elicit a hypersensitive reaction (HR) in tobacco leaves. Synthetic C6HSL was less effective at inducing pigment production than 3OC6HSL at 10 μM. The bruI mutant Br-212 did not produce detectable AHLs, indicating that C6HSL and 3OC6HSL are the major AHLs produced by this species. The AHLs N-heptanoyl-DL-homoserine lactone (C7HSL), N-octanoyl-DL-homoserine lactone (C8HSL), and N-(3-oxooctanoyl)-DL-homoserine lactone (3OC8HSL) also induced pigment production in Br-212 and restored its ability to elicit an HR in tobacco, suggesting that cross-talk with other bacterial species may be possible.
authors.affiliation: Crops Pathology and Genetics Research Unit, United States Department of Agriculture-Agricultural Research Service, Department of Plant Pathology, University of California, Davis, CA 95616, USA.
authors.forename: Ali E
authors.initials: AE
authors.lastname: McClean
authors.forename: Breck A
authors.initials: BA
authors.lastname: Duerkop
authors.forename: E Peter
authors.initials: EP
authors.lastname: Greenberg
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Kluepfel
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D054742:Acyl-Butyrolactones / Q000378:metabolism* / Q000494:pharmacology; D045424:Complex Mixtures / Q000737:chemistry; D004755:Enterobacteriaceae / Q000737:chemistry / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D005798:Genes, Bacterial / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics; D016254:Mutagenesis, Insertional; D010641:Phenotype; D010860:Pigments, Biological / Q000096:biosynthesis*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D057865:Plant Immunity; D018515:Plant Leaves / Q000382:microbiology; D011725:Pyridines / Q000378:metabolism; D011758:Pyrroles / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014026:Nicotiana / Q000276:immunology* / Q000382:microbiology
chemical_list: D054742:Acyl-Butyrolactones; D045424:Complex Mixtures; C511789:N-(3-oxooctanoyl)homoserine lactone; C104908:N-hexanoyl-L-homoserine lactone; D010860:Pigments, Biological; D011725:Pyridines; D011758:Pyrroles; C587463:rubrifacine; D015107:4-Butyrolactone