title: Bacterial discrimination by dictyostelid amoebae reveals the complexity of ancient interspecies interactions.
abstract: BACKGROUND
  Amoebae and bacteria interact within predator-prey and host-pathogen relationships, but the general response of amoeba to bacteria is not well understood. The amoeba Dictyostelium discoideum feeds on, and is colonized by, diverse bacterial species, including Gram-positive [Gram(+)] and Gram-negative [Gram(-)] bacteria, two major groups of bacteria that differ in structure and macromolecular composition.
  
  
  RESULTS
  Transcriptional profiling of D. discoideum revealed sets of genes whose expression is enriched in amoebae interacting with different species of bacteria, including sets that appear specific to amoebae interacting with Gram(+) or with Gram(-) bacteria. In a genetic screen utilizing the growth of mutant amoebae on a variety of bacteria as a phenotypic readout, we identified amoebal genes that are only required for growth on Gram(+) bacteria, including one that encodes the cell-surface protein gp130, as well as several genes that are only required for growth on Gram(-) bacteria, including one that encodes a putative lysozyme, AlyL. These genes are required for parts of the transcriptional response of wild-type amoebae, and this allowed their classification into potential response pathways.
  
  
  CONCLUSIONS
  We have defined genes that are critical for amoebal survival during feeding on Gram(+), or Gram(-), bacteria that we propose form part of a regulatory network that allows D. discoideum to elicit specific cellular responses to different species of bacteria in order to optimize survival.
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Waleed
authors.initials: W
authors.lastname: Nasser
authors.forename: Balaji
authors.initials: B
authors.lastname: Santhanam
authors.forename: Edward Roshan
authors.initials: ER
authors.lastname: Miranda
authors.forename: Anup
authors.initials: A
authors.lastname: Parikh
authors.forename: Kavina
authors.initials: K
authors.lastname: Juneja
authors.forename: Gregor
authors.initials: G
authors.lastname: Rot
authors.forename: Chris
authors.initials: C
authors.lastname: Dinh
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.forename: Blaz
authors.initials: B
authors.lastname: Zupan
authors.forename: Gad
authors.initials: G
authors.lastname: Shaulsky
authors.forename: Adam
authors.initials: A
authors.lastname: Kuspa
mesh_terms: D004023:Dictyostelium / Q000235:genetics / Q000502:physiology*; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D017125:Genes, Protozoan; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000502:physiology*; D006094:Gram-Positive Bacteria / Q000235:genetics / Q000502:physiology*; D054884:Host-Pathogen Interactions / Q000235:genetics; D009154:Mutation; D014158:Transcription, Genetic