title: Quantitative single-cell characterization of bacterial interactions reveals type VI secretion is a double-edged sword.
abstract: Interbacterial interaction pathways play an important role in defining the structure and complexity of bacterial associations. A quantitative description of such pathways offers promise for understanding the forces that contribute to community composition. We developed time-lapse fluorescence microscopy methods for quantitation of interbacterial interactions and applied these to the characterization of type VI secretion (T6S) in Pseudomonas aeruginosa. Our analyses allowed a direct determination of the efficiency of recipient cell lysis catalyzed by this intercellular toxin delivery pathway and provided evidence that its arsenal extends beyond known effector proteins. Measurement of T6S apparatus localization revealed correlated activation among neighboring cells, which, taken together with genetic data, implicate the elaboration of a functional T6S apparatus with a marked increase in susceptibility to intoxication. This possibility was supported by the identification of T6S-inactivating mutations in a genome-wide screen for resistance to T6S-mediated intoxication and by time-lapse fluorescence microscopy analyses showing a decreased lysis rate of recipient cells lacking T6S function. Our discoveries highlight the utility of single-cell approaches for measuring interbacterial phenomena and provide a foundation for studying the contribution of a widespread bacterial interaction pathway to community structure.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Michele
authors.initials: M
authors.lastname: LeRoux
authors.forename: Justin A
authors.initials: JA
authors.lastname: De Leon
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Kuwada
authors.forename: Alistair B
authors.initials: AB
authors.lastname: Russell
authors.forename: Delia
authors.initials: D
authors.lastname: Pinto-Santini
authors.forename: Rachel D
authors.initials: RD
authors.lastname: Hood
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Agnello
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Robertson
authors.forename: Paul A
authors.initials: PA
authors.lastname: Wiggins
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Mougous
mesh_terms: D008856:Microscopy, Fluorescence; D011550:Pseudomonas aeruginosa / Q000502:physiology*