Molecular Machinery of the Triad Holin, Endolysin, and Spanin: Key Players Orchestrating Bacteriophage-Induced Cell Lysis and their Therapeutic Applications.

Phage therapy has attracted attention as a possible alternative treatment for multi-drug resistance (MDR) infections in recent years. The lytic bacteriophages encode proteins for bacterial host envelope rupture. Phages produce endolysins muralytic enzymes, they are phage-encoded peptidoglycan hydrolases (PGHs) that cause enzymatically breakdown of the host bacterium's peptidoglycan (PG) or murein layer at the end of their lytic multiplication cycle. Phage holins regulate endolysin access to the PG, starting the lysis process at a specific moment 'lysis clock'. Phage spanins disrupt the outer membrane. Holin/Endolysin/Spanin can be utilized as novel antimicrobial agents against infections caused by bacteria. These proteins are generating interest across a variety of industries, including those in the pharmaceutical, food, biotechnological, and medical disciplines. In this review, we highlight the importance of these proteins, and their application in animal studies. Moreover, some clinical trials are mentioned.