Biology subjects

Darnault, C.

Publications and source records attributed to Darnault, C..

2 recordsLinked to original sources

bioRxiv2026

Superinfection exclusion strategy of siphophage T5: analysis of the FhuA:Llp complex

Superinfection exclusion is a widespread viral mechanism that protects the infected cell from over infection by other, identical or closely related viruses. Shortly after infection by bac-teriophage T5, the bacterium E. coli produces Llp coded by the just injected viral genome. Llp is a small lipoprotein targeted to the inner-leaflet of the host outer-membrane. It binds to FhuA, an outer-membrane iron-ferrichrome transporter, which is T5 receptor at the E. coli cell surface. The interaction between Llp and FhuA prevents any further bacteriophage binding and infection. Here, we determined the RMN structure of Llp and analyse the formation of the FhuA:Llp complex using a wide range of techniques and mutants, both in vivo and in vitro. Interaction of Llp to FhuA is governed by a two-step equilibrium with a strong contribution of induced fit: Llp binding requires remodelling of FhuA periplasmic plug surface, allowing the further large conformational reorganisation of the extracellular loops. Analysis of FhuA mu-tants show the importance of the intertwined interactions between the extracellular loops and the plug in the communication between the periplasmic and the extracellular faces of FhuA.

biophysics↗

bioRxiv2022

Structural basis of bacteriophage T5 infection trigger and E. coli cell wall perforation

The vast majority of bacteriophages (phages) - bacterial viruses - present a tail that allows host recognition, cell wall perforation and safe channelling of the viral DNA from the capsid to the cytoplasm of the infected bacterium. The majority of tailed phages bears a long flexible tail (Siphoviridae) at the distal end of which a tip complex, often called baseplate, harbours one or more Receptor Binding Protein{middle dot}s (RBPs). Interaction between the RBPs and the host surface triggers cell wall perforation and DNA ejection, but little is known on these mechanisms for Siphoviridae. Here, we present the structure of siphophage T5 tip at high resolution, determined by electron cryo-microscopy, allowing to trace most of its constituting proteins, including 35 C-terminal residues of the Tape Measure Protein. We also present the structure of T5 tip after interaction with its E. coli receptor FhuA reconstituted into nanodisc. It brings out the dramatic conformational changes underwent by T5 tip upon infection, i.e. bending of the central fibre on the side, opening of the tail tube and its anchoring to the membrane, and formation of a transmembrane channel. These new structures shed light on the mechanisms of host recognition and activation of the viral entry for Siphoviridae.

microbiology↗