Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Taiwan.
Int J Antimicrob Agents. 2013 Aug;42(2):141-8. doi: 10.1016/j.ijantimicag.2013.04.022. Epub 2013 Jun 3.
Acinetobacter baumannii has recently emerged as a major cause of healthcare-associated infections owing to an increase in its antimicrobial resistance to virtually all available drugs. The ability of endolysins (lysozymes) to digest cell walls when applied exogenously to bacterial cells has enabled their use as novel antibacterials. In order to utilise endolysins as a therapeutic alternative to antibiotics, we surveyed the genome sequence of A. baumannii ATCC 17978 and successfully identified two phage-related endolysin genes, A1S_1600 and A1S_2016 (termed lysAB3 and lysAB4, respectively). Following cloning and expression/purification, various antibacterial activities of these two phage-related endolysins were determined in vitro. Zymographic assays showed that only purified LysAB3 could lyse the peptidoglycan of the A. baumannii cell wall. When applied exogenously, both LysAB3 and LysAB4 were active against most Acinetobacter spp. tested but had virtually no activity against other non-Acinetobacter spp. Scanning electron microscopy revealed that exposure to 100μg/mL LysAB3 and LysAB4 for up to 60min caused a remarkable modification of the cell shape of A. baumannii. These results indicate that the genes encoding phage-related endolysins can be readily isolated from the bacterial genome and have potential for the development of novel antimicrobial agents.
鲍曼不动杆菌最近因其对几乎所有现有药物的抗药性增加，成为医疗相关感染的主要原因。内切溶菌酶（溶菌酶）在外源性应用于细菌细胞时能够消化细胞壁，这使其能够被用作新型抗菌药物。为了将内切溶菌酶用作抗生素的治疗替代物，我们对鲍曼不动杆菌 ATCC 17978 的基因组序列进行了调查，并成功鉴定了两个与噬菌体相关的内切溶菌酶基因，A1S_1600 和 A1S_2016（分别称为 lysAB3 和 lysAB4）。在克隆和表达/纯化后，我们在体外测定了这两种与噬菌体相关的内切溶菌酶的各种抗菌活性。酶谱分析表明，只有纯化的 LysAB3 才能裂解鲍曼不动杆菌细胞壁的肽聚糖。当外源性应用时，LysAB3 和 LysAB4 对大多数测试的不动杆菌属均具有活性，但对其他非不动杆菌属几乎没有活性。扫描电子显微镜显示，暴露于 100μg/mL LysAB3 和 LysAB4 长达 60 分钟会导致鲍曼不动杆菌细胞形状发生显著改变。这些结果表明，编码噬菌体相关内切溶菌酶的基因可以从细菌基因组中轻易分离出来，并有可能开发出新型抗菌药物。
