Veronika Theresa Lutz
University of Copenhagen
I’m a Postdoc at the PHAGEBio group at the University of Copenhagen, where I also obtained my PhD. I am an expert in studying phages and phage proteins that interact with bacterial hosts. I gained this expertise through my two master’s degrees and my PhD. In my first master’s in Molecular Life Science, I isolated and characterized B. subtilis bacteriophages. In my PhD, I studied receptor-binding proteins that interact with bacterial receptor proteins, and in my second master’s in Computational Biomedicine, I focused on in silico analysis of protein structures. In this talk, I will focus on the work from my PhD.
Affiliations: (1). Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C (Denmark) (2). Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen (Denmark) (3). Department of Food Science, Cornell University, Ithaca, NY (United States) !Present address: Institute for Conservation, Royal Danish Academy, Copenhagen (Denmark)
Phages recognize their hosts by binding bacterial surface receptors with receptor-binding proteins (RBPs). The RBP Gp38 of Straboviridae phages is particularly noteworthy due to its modular structure featuring conserved glycine-rich motifs (GRMs) interspersed with hypervariable segments (HVS), which enable the phage to interact with outer membrane protein receptors via their extracellular loops. Through a targeted isolation approach, we established a collection of Straboviridae phages from three different genera: Tequatrovirus, Mosigvirus, and Krischvirus, all expressing the Gp38 adhesin protein. We identified the outer membrane proteins OmpA, Tsx, OmpF, and TolC as phage receptors and found that the similarity of Gp38 adhesin proteins correlated with receptor recognition. Focusing on OmpA, we combined in silico adhesin-receptor binding predictions, phage plaque assays on E. coli expressing OmpA variants with diverse outer loop sequences, and a host range analysis across the diverse E. coli reference collection (ECOR). Our findings show that Gp38 variants encoded by phages FL08 and AV119 bind to many OmpA outer loop variants. In contrast, the Gp38 of phages FL12, FL18, and FL20 bind only to a limited number of outer loop variants, resulting in a narrower host range. Finally, phylogenetic analysis of Gp38 revealed distinct groups corresponding to their bacterial receptors, facilitating future receptor predictions for phages. In summary, we identified specific molecular interactions involved in host binding of phages in our Straboviridae phage collection. The phylogeny of Gp38 allows prediction of receptors of Straboviridae phages, which is crucial for the efficiency of phage therapy applications.