Evaluation of Bacteriophage ϕ11 host recognition protein and its host-binding peptides for diagnosing/targeting of Saphylococcus aureus infections

Evaluating the potential of using both synthetic and biological products as targeting agents for the diagnosis, imaging, and treatment of infections due to particularly antibiotic-resistant pathogens is important for controlling infections. We examined the interaction between Gp45, a receptor-binding protein of the ϕ11 lysogenic phage, and its host S. aureus, a common cause of nosocomial infections. Using molecular dynamics and docking simulations, we identified the peptides that bind to S. aureus wall teichoic acids via Gp45. We compared the binding affinity of Gp45 and the two highest-scoring peptide sequences (P1 and P3) and their scrambled forms using microscopy, spectroscopy, and ELISA. Our results revealed that rGp45 (recombinant Gp45) and chemically synthesized P1 had a higher binding affinity for S. aureus compared with all other peptides, with the exception of E. coli. Furthermore, rGp45 had a capture efficiency of over 86%; P1 had a capture efficiency of over 64%. Overall, our findings suggest that receptor-binding proteins such as rGp45, which provide a critical initiation of the phage life cycle for host adsorption, might play an important role in the diagnosis, imaging, and targeting of bacterial infections. Studying such proteins could accordingly enable the development of effective strategies for controlling infections.