Expression dynamics of the CfrBI restriction-modification system in single cells and the impact on restriction of phage infection for the bacterial population

• Applicant: Dr. Johannes Gibhardt
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms ; General Genetics and Functional Genome Biology ; Parasitology and Biology of Tropical Infectious Disease Pathogens ; Cell Biology
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 440930027

Multiple drug-resistant bacteria are an increasing problem for modern health care institutions. It is therefore deemed necessary to facilitate the research in novel approaches to combat pathogenic bacteria. Bacteriophages are bacteria-specific viruses and a promising tool due to their high host-specificity and efficiency to lyse bacterial cells. However, bacteria can also acquire resistances against phages and phages can overcome bacterial resistances. Studies are needed to deepen our understanding of the co-evolutionary processes and mechanisms of phage resistance. One of the most widespread and mobile mechanisms bacteria use to combat infections by phages are plasmid-encoded restriction modification (R-M) systems. These systems recognize a specific DNA sequence and consist of a methyltransferase (MT) and a restriction endonuclease (RE) that, upon binding to the recognition sequence, methylate or cleave the DNA, respectively. Methylation leads to resistance of the DNA against the corresponding RE. During the acquisition of such a plasmid-based R-M system, the timely orchestrated expression of the MT- and RE-encoding genes is key to establish protection and to prevent modification of virus DNA that would render the system non-functional, leading to the production of resistant phage progenies that would threaten the survival of the whole bacterial population. While progress has been made in the study of the regulatory mechanism of R-M systems in vitro, little is known about the regulatory dynamics in vivo. The following proposal aims to increase our understanding about the regulation of R-M systems in vivo, their dynamics during their establishment in single cells, involved factors and the consequences for their protective function of bacterial cells and populations. Eventually, the gain in knowledge will help to progress our understanding of the interaction and co-evolution of bacteria and phages and the prospect of phage therapy for bacterial infections.

• DFG Programme: WBP Fellowship
• International Connection: Russia
• Hosts: Dr. Mikhail Khodorkovskiy, until 3/2022; Dr. Konstantin Severinov, until 3/2022