Infections caused by antibiotic-resistant bacteria are a growing health concern. As antibiotic treatments become less effective, alternative approaches are explored. One of the promising methods is phage therapy. However, our understanding of phage–bacterium interactions is limited, and phage therapy is currently considered an experimental treatment.
We use cryo-electron microscopy to study the structure of bacteriophage LUZ19 and the process of LUZ19 infection of PAO1, a clinically relevant strain of P. aeruginosa. The virion particle is composed of an icosahedral capsid and a tail decorated by six long tail fibres. The capsid is built from major capsid, head cement, and flexible head decoration proteins, and encloses a 43.5 kbp-long dsDNA genome and an inner core complex. The symmetry mismatch between the capsid and the tail is mediated by a dodecameric portal complex which occupies one vertex of the capsid. The portal complex interacts with the adaptor dodecamer of the tail through its “stem” helices which interlock with the adaptor C-termini. LUZ19 tail extends to a hexameric tail nozzle which is decorated with six flexible tail fibres. The nozzle and the tail fibres mediate the attachment of phage LUZ19 to the type IV pili of PAO1. The contraction of the pili carries the phages to the cell surface, where they irreversibly attach and infect the host cell.
Studying phage LUZ19's structure and its infection mechanism aims to deepen our understanding of phage-bacterium interaction.
Cryo-electron Microscopy and Tomography core facility (CEMCOF) of CEITEC Masaryk University is gratefully acknowledged for obtaining the scientific data presented in this poster.