title: Interbacterial signaling via Burkholderia contact-dependent growth inhibition system proteins.
abstract: In prokaryotes and eukaryotes, cell-cell communication and recognition of self are critical to coordinate multicellular functions. Although kin and kind discrimination are increasingly appreciated to shape naturally occurring microbe populations, the underlying mechanisms that govern these interbacterial interactions are insufficiently understood. Here, we identify a mechanism of interbacterial signal transduction that is mediated by contact-dependent growth inhibition (CDI) system proteins. CDI systems have been characterized by their ability to deliver a polymorphic protein toxin into the cytoplasm of a neighboring bacterium, resulting in growth inhibition or death unless the recipient bacterium produces a corresponding immunity protein. Using the model organism Burkholderia thailandensis, we show that delivery of a catalytically active CDI system toxin to immune (self) bacteria results in gene expression and phenotypic changes within the recipient cells. Termed contact-dependent signaling (CDS), this response promotes biofilm formation and other community-associated behaviors. Engineered strains that are isogenic with B. thailandensis, except the DNA region encoding the toxin and immunity proteins, did not display CDS, whereas a strain of Burkholderia dolosa producing a nearly identical toxin-immunity pair induced signaling in B. thailandensis Our data indicate that bcpAIOB loci confer dual benefits; they direct antagonism toward non-self bacteria and promote cooperation between self bacteria, with self being defined by the bcpAIOB allele and not by genealogic relatedness.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Garcia
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Perault
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Sara A
authors.initials: SA
authors.lastname: Marlatt
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 peggy_cotter@med.unc.edu.
authors.forename: Peggy A
authors.initials: PA
authors.lastname: Cotter
mesh_terms: D018407:Bacterial Physiological Phenomena; D001427:Bacterial Toxins; D018441:Biofilms; D019117:Burkholderia / Q000254:growth & development / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D056265:Microbial Interactions / Q000502:physiology; D015398:Signal Transduction
chemical_list: D001427:Bacterial Toxins; D008565:Membrane Proteins; C031717:growth inhibitory proteins
keywords: biofilm; contact-dependent competition; signal transduction; sociomicrobiology; two-partner secretion