Carpe pili! Hunting strategy of phage JBD30 revealed by combination of cryo-electron and fluorescent microscopy
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| Year of publication | 2023 |
| Type | Conference abstract |
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| Description | Increasing numbers of infections caused by multi-drug resistant bacteria have renewed the interest in phage therapy. However, the exact mechanisms of phage – bacterium interaction are not known for the most of them. Here, we present the virion structure and infection strategy of Siphoviridae bacteriophage JBD30 revealed by the combination of cryo-electron and fluorescent microscopy. Bacteriophage JBD30 uses its tail fibres for recognising P. aeruginosa pili type IV. After the attachment to pili, the virion either diffuses along it or is pulled by pili retraction towards the cellular surface, where it irreversibly binds by the tripod complex of receptor binding protein trimers. Afterwards, the phage punctures the outer cellular membrane and degrades the peptidoglycan layer using the enzymatically active domains of receptor binding protein and tape measure protein C-terminal trimeric ?-helical coiled coil domain. Bioinformatic analysis of tape measure protein showed that its N-terminal part is composed of three domains: hydrophobic transmembrane domain I (residues 57–79), cytoplasmic domain (residues 80–384) and hydrophobic transmembrane domain II (residues 385–409). Furthermore, the estimated size of these domains corresponds to the thickness of P. aeruginosa cellular membranes. We assume that the N-terminal part of the tape measure protein might form a channel spanning the whole cell wall facilitating DNA transition from the virion capsid into the host cytoplasm. New phage progeny is released approximately 80 minutes post ejection of phage DNA into the host cell. The combination of cryo-electron microscopy analysis techniques, cryo-electron tomography and fluorescent microscopy allowed us to propose the mechanism of key stages of phage infection and describe it at time resolved molecular level. |
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