Epitopes in the capsular polysaccharide and the porin OmpK36 receptors are required for bacteriophage infection of Klebsiella pneumoniae
Rhys A. Dunstan,
Rebecca S. Bamert,
Kher Shing Tan,
Uvini Imbulgoda,
Christopher K. Barlow,
George Taiaroa,
Derek J. Pickard,
Ralf B. Schittenhelm,
Gordon Dougan,
Francesca L. Short,
Trevor Lithgow
Affiliations
Rhys A. Dunstan
Centre to Impact AMR, Monash University, Clayton, VIC, Australia; Infection Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia; Corresponding author
Rebecca S. Bamert
Centre to Impact AMR, Monash University, Clayton, VIC, Australia; Infection Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
Kher Shing Tan
Centre to Impact AMR, Monash University, Clayton, VIC, Australia; Infection Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
Uvini Imbulgoda
Centre to Impact AMR, Monash University, Clayton, VIC, Australia; Infection Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
Christopher K. Barlow
Monash Proteomics & Metabolomics Platform, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
George Taiaroa
Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Clayton, VIC, Australia
Derek J. Pickard
Department of Medicine, University of Cambridge, Cambridge, UK
Ralf B. Schittenhelm
Monash Proteomics & Metabolomics Platform, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
Gordon Dougan
Department of Medicine, University of Cambridge, Cambridge, UK
Francesca L. Short
Centre to Impact AMR, Monash University, Clayton, VIC, Australia; Infection Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia; Department of Medicine, University of Cambridge, Cambridge, UK; Wellcome Sanger Institute, Hinxton, Cambridgeshire, UK
Trevor Lithgow
Centre to Impact AMR, Monash University, Clayton, VIC, Australia; Infection Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia; Corresponding author
Summary: To kill bacteria, bacteriophages (phages) must first bind to a receptor, triggering the release of the phage DNA into the bacterial cell. Many bacteria secrete polysaccharides that had been thought to shield bacterial cells from phage attack. We use a comprehensive genetic screen to distinguish that the capsule is not a shield but is instead a primary receptor enabling phage predation. Screening of a transposon library to select phage-resistant Klebsiella shows that the first receptor-binding event docks to saccharide epitopes in the capsule. We discover a second step of receptor binding, dictated by specific epitopes in an outer membrane protein. This additional and necessary event precedes phage DNA release to establish a productive infection. That such discrete epitopes dictate two essential binding events for phages has profound implications for understanding the evolution of phage resistance and what dictates host range, two issues critically important to translating knowledge of phage biology into phage therapies.
