Schmelcher Mathias, Shen Yang, Nelson Daniel C, Eugster Marcel R, Eichenseher Fritz, Hanke Daniela C, Loessner Martin J, Dong Shengli, Pritchard David G, Lee Jean C, Becker Stephen C, Foster-Frey Juli, Donovan David M
Animal Biosciences and Biotechnology Laboratory, ANRI, NEA, ARS, USDA, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich, Switzerland
Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich, Switzerland Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD 20850, USA.
J Antimicrob Chemother. 2015 May;70(5):1453-65. doi: 10.1093/jac/dku552. Epub 2015 Jan 27.
In the light of increasing drug resistance in Staphylococcus aureus, bacteriophage endolysins [peptidoglycan hydrolases (PGHs)] have been suggested as promising antimicrobial agents. The aim of this study was to determine the antimicrobial activity of nine enzymes representing unique homology groups within a diverse class of staphylococcal PGHs.
PGHs were recombinantly expressed, purified and tested for staphylolytic activity in multiple in vitro assays (zymogram, turbidity reduction assay and plate lysis) and against a comprehensive set of strains (S. aureus and CoNS). PGH cut sites in the staphylococcal peptidoglycan were determined by biochemical assays (Park-Johnson and Ghuysen procedures) and MS analysis. The enzymes were tested for their ability to eradicate static S. aureus biofilms and compared for their efficacy against systemic MRSA infection in a mouse model.
Despite similar modular architectures and unexpectedly conserved cleavage sites in the peptidoglycan (conferred by evolutionarily divergent catalytic domains), the enzymes displayed varying degrees of in vitro lytic activity against numerous staphylococcal strains, including cell surface mutants and drug-resistant strains, and proved effective against static biofilms. In a mouse model of systemic MRSA infection, six PGHs provided 100% protection from death, with animals being free of clinical signs at the end of the experiment.
Our results corroborate the high potential of PGHs for treatment of S. aureus infections and reveal unique antimicrobial and biochemical properties of the different enzymes, suggesting a high diversity of potential applications despite highly conserved peptidoglycan target sites.
鉴于金黄色葡萄球菌的耐药性不断增加，噬菌体溶菌酶[肽聚糖水解酶（PGHs）]被认为是有前景的抗菌剂。本研究的目的是确定代表不同类葡萄球菌PGHs中独特同源组的九种酶的抗菌活性。
重组表达、纯化PGHs，并在多种体外试验（酶谱分析、浊度降低试验和平板裂解试验）中检测其溶葡萄球菌活性，并针对一组全面的菌株（金黄色葡萄球菌和凝固酶阴性葡萄球菌）进行检测。通过生化试验（帕克-约翰逊法和居伊森法）和质谱分析确定葡萄球菌肽聚糖中的PGH切割位点。测试这些酶消除静态金黄色葡萄球菌生物膜的能力，并在小鼠模型中比较它们对全身性耐甲氧西林金黄色葡萄球菌感染的疗效。
尽管这些酶具有相似的模块化结构，且肽聚糖中的切割位点意外保守（由进化上不同的催化结构域赋予），但它们对众多葡萄球菌菌株，包括细胞表面突变体和耐药菌株，表现出不同程度的体外裂解活性，并证明对静态生物膜有效。在全身性耐甲氧西林金黄色葡萄球菌感染的小鼠模型中，六种PGHs提供了100%的死亡保护，实验结束时动物没有临床症状。
我们的结果证实了PGHs在治疗金黄色葡萄球菌感染方面的巨大潜力，并揭示了不同酶独特的抗菌和生化特性，表明尽管肽聚糖靶位点高度保守，但潜在应用具有高度多样性。
