Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, USA.
Adv Virus Res. 2012;83:299-365. doi: 10.1016/B978-0-12-394438-2.00007-4.
Peptidoglycan (PG) is the major structural component of the bacterial cell wall. Bacteria have autolytic PG hydrolases that allow the cell to grow and divide. A well-studied group of PG hydrolase enzymes are the bacteriophage endolysins. Endolysins are PG-degrading proteins that allow the phage to escape from the bacterial cell during the phage lytic cycle. The endolysins, when purified and exposed to PG externally, can cause "lysis from without." Numerous publications have described how this phenomenon can be used therapeutically as an effective antimicrobial against certain pathogens. Endolysins have a characteristic modular structure, often with multiple lytic and/or cell wall-binding domains (CBDs). They degrade the PG with glycosidase, amidase, endopeptidase, or lytic transglycosylase activities and have been shown to be synergistic with fellow PG hydrolases or a range of other antimicrobials. Due to the coevolution of phage and host, it is thought they are much less likely to invoke resistance. Endolysin engineering has opened a range of new applications for these proteins from food safety to environmental decontamination to more effective antimicrobials that are believed refractory to resistance development. To put phage endolysin work in a broader context, this chapter includes relevant studies of other well-characterized PG hydrolase antimicrobials.
肽聚糖（PG）是细菌细胞壁的主要结构成分。细菌具有自溶 PG 水解酶，使细胞能够生长和分裂。研究得很好的一组 PG 水解酶是噬菌体内切酶。内切酶是 PG 降解蛋白，使噬菌体在噬菌体裂解周期中从细菌细胞中逸出。当内切酶被纯化并暴露于 PG 外部时，可以引起“从外部裂解”。许多出版物都描述了如何将这种现象用作针对某些病原体的有效抗菌治疗方法。内切酶具有特征性的模块化结构，通常具有多个溶菌和/或细胞壁结合结构域（CBD）。它们通过糖苷酶、酰胺酶、内肽酶或溶菌转糖基酶活性降解 PG，并已被证明与其他 PG 水解酶或一系列其他抗菌剂具有协同作用。由于噬菌体和宿主的共同进化，人们认为它们不太可能引起耐药性。内切酶工程为这些蛋白质开辟了从食品安全到环境净化的一系列新应用，以及更有效的抗菌剂，这些抗菌剂被认为不易产生耐药性发展。为了更广泛地了解噬菌体内切酶的工作，本章包括了对其他特征明确的 PG 水解酶抗菌剂的相关研究。
