Molecular sensing mechanisms of phage infection mediated through the Zorya anti-bacteriophage defense system

• Applicants: Professor Dr. Marc Erhardt; Dr. Philipp Popp
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548567920

In the complex interplay between bacteriophages (phages) and their bacterial hosts, anti-phage defense mechanisms like the recently discovered Zorya system play a crucial role to ensure bacterial survival. Three Zorya subtypes have been identified, yet much remains unknown about how this system detects and counters phage infections. Our preliminary work, in collaboration with Nicholas Taylor of the University of Copenhagen, has begun to unravel the structural and functional aspects of the E. coli Zorya type I system composed of the membrane proteins ZorAB, which are homologous to the stator units MotAB of the bacterial flagellum, and the cytoplasmic effector proteins ZorCD. Building on these foundations, we aim to elucidate the molecular mechanisms behind the Zorya anti-phage defense system. Using a combination of structure-based mutagenesis approaches and functional assays in combination with advanced microscopy, including live-cell total-internal reflection fluorescence (TIRF) and superresolution STED microscopy, we will explore how phage infection is sensed by the host cell, leading to the activation of the Zorya system, how Zorya components are recruited to the infection site to prevent phage replication and if the sensing and anti-phage mechanism is conserved among Zorya sub-types. The project is structured into three work packages. (i) Determing the regulatory and sensing mechanisms that control Zorya expression and activation. (ii) Visualizing the interaction between invading phages and Zorya components, focusing on the structural and functional roles of ZorAB. (iii) Comparing the mechanistic conservation across Zorya system sub-types. Through this comprehensive approach, we anticipate uncovering the intricate molecular details of the Zorya system, contributing to our fundamental understanding of bacterial immune strategies against phages.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2330: New concepts in prokaryotic virus-host interactions - from single cells to microbial communities
• International Connection: Denmark
• Cooperation Partner: Professor Nicholas Taylor