Prophages mediate defense against phage infection through diverse mechanisms.
The activity of bacteriophages poses a major threat to bacterial survival. Upon infection, a temperate phage can either kill the host cell or be maintained as a prophage. In this state, the bacteria carrying the prophage is at risk of superinfection, where another phage injects its genetic material and competes for host cell resources. To avoid this, many phages have evolved mechanisms that alter the bacteria and make it resistant to phage superinfection. The mechanisms underlying these phentoypic conversions and the fitness consequences for the host are poorly understood, and systematic studies of superinfection exclusion mechanisms are lacking. In this study, we examined a wide range of Pseudomonas aeruginosa phages and found that they mediate superinfection exclusion through a variety of mechanisms, some of which affected the type IV pilus and O-antigen, and others that functioned inside the cell. The strongest resistance mechanism was a surface modification that we showed is cost-free for the bacterial host in a natural soil environment and in a Caenorhabditis. elegans infection model. This study represents the first systematic approach to address how a population of prophages influences phage resistance and bacterial behavior in P. aeruginosa.
Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
Joseph
J
Bondy-Denomy
Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
Jason
J
Qian
Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK.
Edze R
ER
Westra
Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK.
Angus
A
Buckling
Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON, Canada.|Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
David S
DS
Guttman
Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.|Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
Alan R
AR
Davidson
Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.
Karen L
KL
Maxwell
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001435:Bacteriophages / Q000235:genetics / Q000502:physiology*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism; D039002:Prophages / Q000235:genetics / Q000502:physiology*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism / Q000821:virology*
D001426:Bacterial Proteins