title: Extensive and specific responses of a eukaryote to bacterial quorum-sensing signals.
abstract: Many bacteria use N-acyl homoserine lactone (AHL) signals to coordinate the behavior of individual cells in a local population. The successful infection of eukaryotic hosts by bacteria seems to depend particularly on such AHL-mediated "quorum-sensing" regulation. We have used proteome analysis to show that a eukaryotic host, the model legume Medicago truncatula, is able to detect nanomolar to micromolar concentrations of bacterial AHLs from both symbiotic (Sinorhizobium meliloti) and pathogenic (Pseudomonas aeruginosa) bacteria, and that it responds in a global manner by significant changes in the accumulation of over 150 proteins, 99 of which have been identified by peptide mass fingerprinting. The accumulation of specific proteins and isoforms depended on AHL structure, concentration, and time of exposure. AHLs were also found to induce tissue-specific activation of beta-glucuronidase (GUS) reporter fusions to an auxin-responsive and three chalcone synthase promoters, consistent with AHL-induced changes in the accumulation of auxin-responsive and flavonoid synthesis proteins. In addition, exposure to AHLs was found to induce changes in the secretion of compounds by the plants that mimic quorum-sensing signals and thus have the potential to disrupt quorum sensing in associated bacteria. Our results indicate that eukaryotes have an extensive range of functional responses to AHLs that may play important roles in the beneficial or pathogenic outcomes of eukaryote-prokaryote interactions.
authors.affiliation: Genomic Interactions Group, Research School of Biological Sciences, Australian National University, GPO Box 475, Canberra ACT 2601, Australia.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mathesius
authors.forename: Susan
authors.initials: S
authors.lastname: Mulders
authors.forename: Mengsheng
authors.initials: M
authors.lastname: Gao
authors.forename: Max
authors.initials: M
authors.lastname: Teplitski
authors.forename: Gustavo
authors.initials: G
authors.lastname: Caetano-Anolles
authors.forename: Barry G
authors.initials: BG
authors.lastname: Rolfe
authors.forename: Wolfgang D
authors.initials: WD
authors.lastname: Bauer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D017930:Genes, Reporter; D005838:Genotype; D005966:Glucuronidase / Q000378:metabolism; D029902:Medicago / Q000382:microbiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots; D030821:Plants, Genetically Modified / Q000382:microbiology; D020033:Protein Isoforms; D020543:Proteome; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013997:Time Factors; D019076:Transgenes; D015854:Up-Regulation
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; D020543:Proteome; D005966:Glucuronidase