Innate immune proteins are antibacterial substances which have existed for millions of years. Their action sites are mainly directed to essential fragments of prokaryotes, so it’s difficult to develop drug-resistant strains.
PGRP is an innate immune protein that binds to peptidoglycan on the bacterial membrane, causing changes in oxidation, thiol or metal ions.
PGRP accelerates the TCA cycle and increases the formation of hydrogen peroxide (H2O2) and hydroxyl radicals (HO·).
PGRP may also cause the consumption of more than 90% of the thiol groups in the cell, which destroys the redox balance of the cells.
The third method of PGRP increases intracellular free Zn2+ and Cu+, which inactivates the enzyme or accelerates the consumption of thiol groups.
In contrast, antibiotics can only produce antibacterial effects in a single location; PGRP can use multiple pathways to inhibit bacteria, but PGRP research is not yet complete and there is currently no commercial PGRP for medical use in the future. If you can use PGRP in a large number of successful ways, it is believed that it will have a significant positive effect on our medicine.
Full paper : Dziarski, Roman, and Dipika Gupta. “How innate immunity proteins kill bacteria and why they are not prone to resistance." Current genetics 64.1 (2018): 125-129.