Receptor Polymorphism Restricts Contact-Dependent Growth Inhibition to Members of the Same Species

摘要: ABSTRACT Bacteria that express contact-dependent growth inhibition (CDI) systems outcompete siblings lack immunity, suggesting CDI mediates intercellular competition. To further explore the role of in competition, we determined target cell range EC93 system from Escherichia coli EC93. The CdiA effector protein recognizes widely conserved BamA as a receptor, yet E. does not inhibit other enterobacterial species. predicted membrane topology indicates three its extracellular loops vary considerably between species, loop heterogeneity may control specificity. Consistent with this hypothesis, enterobacteria are sensitized to upon expression E .  bamA and cells become resistant when is replaced alleles Our data indicate 6 7 form -binding epitope their variation species restricts selection. Although dramatically these regions identical hundreds strains, Ecoli play self-nonself discrimination. IMPORTANCE Contact-dependent widespread among Gram-negative bacteria, enabling them bind neighboring bacterial deliver toxins growth. In study, tested interspecies competition using intestinal isolate an inhibitor model. inhibits different intestine completely CDI. We show resistance due small variations receptor prevent being recognized cells. interactions thus provide mechanism by which bacteria can distinguish close relatives (self) more distant or (nonself). results possible means antimicrobials could be directed one only few related pathogens specific “zip code.”