title: Are CDI Systems Multicolored, Facultative, Helping Greenbeards?
abstract: Competitive and cooperative interactions between organisms, including bacteria, can significantly impact the composition of a community and the fitness of its members, as well as the fitness of their hosts when communities are living on or within other organisms. Understanding the underlying mechanisms is critical to the development of strategies to control microbiological communities that impact animal and plant health and also for understanding the evolution of social behaviors, which has been challenging for evolutionary biologists. Contact-dependent growth inhibition (CDI) is a phenomenon defined by the delivery of a protein toxin to the cytoplasm of neighboring bacteria upon cell-cell contact, resulting in growth inhibition or death unless a specific immunity protein is present. CDI was first described based on observations of interbacterial killing and has been assumed to function primarily as a means of eliminating competitor cells. However, recent molecular evidence indicates that multiple levels of specificity restrict CDI toxin delivery and activity to the same bacterial strain, and that CDI system proteins can mediate cooperative behaviors among 'self' cells, a phenomenon called contact-dependent signaling (CDS). Here we review these recent findings and discuss potential biological and evolutionary implications of CDI system-mediated interbacterial competition and cooperation.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, NC, USA.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Danka
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, KY, USA.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Garcia
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, NC, USA. Electronic address: peggy_cotter@med.unc.edu.
authors.forename: Peggy A
authors.initials: PA
authors.lastname: Cotter
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D019117:Burkholderia / Q000254:growth & development / Q000378:metabolism; D003260:Contact Inhibition / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000502:physiology; D056265:Microbial Interactions; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C031717:growth inhibitory proteins