8b14
T5 Receptor Binding Protein pb5 in complex with its E. coli receptor FhuA
Structural highlights
FunctionFHUA_ECOLI This receptor binds the ferrichrome-iron ligand. It interacts with the TonB protein, which is responsible for energy coupling of the ferrichrome-promoted iron transport system. Acts as a receptor for bacteriophage T5 as well as T1, phi80 and colicin M. Binding of T5 triggers the opening of a high conductance ion channel. Can also transport the antibiotic albomycin.[1] Publication Abstract from PubMedBacteriophages, viruses infecting bacteria, recognize their host with high specificity, binding to either saccharide motifs or proteins of the cell wall of their host. In the majority of bacteriophages, this host recognition is performed by receptor binding proteins (RBPs) located at the extremity of a tail. Interaction between the RBPs and the host is the trigger for bacteriophage infection, but the molecular details of the mechanisms are unknown for most bacteriophages. Here, we present the electron cryomicroscopy (cryo-EM) structure of bacteriophage T5 RBP(pb5) in complex with its Escherichia coli receptor, the iron ferrichrome transporter FhuA. Monomeric RBP(pb5) is located at the extremity of T5's long flexible tail, and its irreversible binding to FhuA commits T5 to infection. Analysis of the structure of RBP(pb5) within the complex, comparison with its AlphaFold2-predicted structure, and its fit into a previously determined map of the T5 tail tip in complex with FhuA allow us to propose a mechanism of transmission of the RBP(pb5) receptor binding to the straight fiber, initiating the cascade of events that commits T5 to DNA ejection. IMPORTANCE Tailed bacteriophages specifically recognize their bacterial host by interaction of their receptor binding protein(s) (RBPs) with saccharides and/or proteins located at the surface of their prey. This crucial interaction commits the virus to infection, but the molecular details of this mechanism are unknown for the majority of bacteriophages. We determined the structure of bacteriophage T5 RBP(pb5) in complex with its E. coli receptor, FhuA, by cryo-EM. This first structure of an RBP bound to its protein receptor allowed us to propose a mechanism of transmission of host recognition to the rest of the phage, ultimately opening the capsid and perforating the cell wall and, thus, allowing safe channeling of the DNA into the host cytoplasm. Deciphering Bacteriophage T5 Host Recognition Mechanism and Infection Trigger.,Degroux S, Effantin G, Linares R, Schoehn G, Breyton C J Virol. 2023 Mar 30;97(3):e0158422. doi: 10.1128/jvi.01584-22. Epub 2023 Feb 13. PMID:36779755[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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