Baseplate structure of bacteriophage phi812 reveals functions of host cell recognition and cell wall degradation
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| Year of publication | 2021 |
| Type | Conference abstract |
| MU Faculty or unit | |
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| Description | Antibiotic-resistant strains of Staphylococcus aureus cause human infections that are difficult to treat and can lead to death. Bacteriophage (phage) phi812K1/420 from the family Myoviridae has been found to infect 95% of tested S. aureus strains and therefore is considered as a potential phage therapy agent. As the native phage particle approaches its host cell, primary phage receptors make a contact with the host cell wall. This interaction triggers cascade of structural changes in the baseplate, resulting in phage tail contraction and genome delivery. Mechanistic description of the baseplate re-organization, however, remains unknown. Using cryo-electron microscopy (cryo-EM), we reconstructed the phage baseplate before and after the attachment to host cell. Moreover, we performed cryo-EM single-particle analysis of recombinant tail spike protein (TSP). Dislocation of the TSP from the center of native phage baseplate suggests that it may play a role in triggering the whole contraction mechanism. The structures of the baseplate were reconstructed in resolution of 3.5-5 A and we are in process of building individual protein structures. We have already solved the structure of the C-terminal domain of TSP with putative glycerol-diesterase activity, which sticks out from the phage baseplate. Such orientation suggests that the TSP can readily degrade host call wall upon phage attachment, making way for tail tube insertion. We assume that as the TSP C-terminal domain is drawn towards the cell wall, the N-terminal domain detaches from phage baseplate, causing instability and consequent baseplate re-organization. |
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