Bacteriophages are fascinating objects, both structurally and in terms of their potential in the fight against bacteria.
Electron microscopy is a tool that is particularly well suited to the study of the structure and life cycle of phages. It allows full use of the team’s instruments and expertise. Classical cryo-electron microscopy coupled with image analysis allows the structures of the different parts of the virus to be obtained, and tomography of phage-infected bacteria can be used to address the different aspects of the phage life cycle.
We are particularly interested in the family Caudovirales which is divided into three groups:
– Siphoviridae, characterised by a long non-contractile tail, form the largest family (60% of caudae viruses). We are collaborating with the IBS team Structure and Stability of Integral Membran Proteins and Phage Assemblies (C. Breyton in charge) to dissect the infection of E coli by the T5 phage.
– Myoviridae have long contractile tails, consisting of an outer tube that contracts around a rigid central tube when the virus is on the surface of its host bacteria. Bacteriophages with a genome size greater than 200 kbp are called jumbo phages (jumbo phages also exist in the Siphoviridae). In collaboration with Takashi Yamada (Hiroshima University), we have studied and compared several viruses of this type (RSL1, RSL2, EcS1, XacN1, RP13 etc.).
– Podoviridae have small non-contractile tails. They incorporate proteins in their capsid that serve to package the DNA in the capsid during virion formation and are ejected into the host wall prior to DNA ejection. We are studying the CARIN1 phage in collaboration with Anne-Claire Baudoux (Roscoff).