TriSH · Unveiling the tripartite dynamics between satellites, helper phages and bacteria

Phages, viruses that infect bacteria, play key roles in shaping bacterial fitness and evolution. At the same time, phages themselves are parasitized by satellites - mobile genetic elements (MGEs) lacking genes for autonomous replication but that can hijack (helper) phages for their own propagation. Despite billions of years of coevolution between satellites, phages and bacteria, we know little about how selection affects these elements and their interactions. Recent studies showed that P4-like satellites are diverse and widespread across distant bacterial genomes, but outside a few P2-like prophages described decades ago, the actual range of phages that P4-like elements can hijack is unknown. The aim of my project is to decipher the mobilization potential of P4-like satellites, study the genetic basis of this mobilization and reveal how selection acts on satellites, phages and bacteria when they coevolve. With access to over 200 strains of Escherichia coli and Klebsiella, I will combine experimental and computational analyses to shed light on the genetic and evolutionary interactions between P4-like satellites, their helpers and their common bacterial hosts. Leveraging my expertise in microbial evolution and molecular biology, this project will introduce new expertise in satellite biology, bioinformatics, and coevolutionary microbiology. This project will provide new models to explore satellite-helper dynamics, with potential applications in biotechnology and phage therapy. At the Institut Pasteur, I will collaborate in an interdisciplinary environment within the Department of Genomes and Genetics, receiving outstanding academic training with numerous opportunities for interdisciplinary collaborations. This provides unique prospects for my career development towards independency. Research findings will be published in high-impact journals, open-access, and presented at international conferences, with outreach efforts to engage a broad audience.