Gottschalk Sanne, Gottlieb Caroline T, Vestergaard Martin, Hansen Paul R, Gram Lone, Ingmer Hanne, Thomsen Line E
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark.
National Institute of Aquatic Resources, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
J Med Microbiol. 2015 Dec;64(12):1504-1513. doi: 10.1099/jmm.0.000177. Epub 2015 Sep 28.
The rapid rise in antibiotic-resistant pathogens is causing increased health concerns, and consequently there is an urgent need for novel antimicrobial agents. Antimicrobial peptides (AMPs), which have been isolated from a wide range of organisms, represent a very promising class of novel antimicrobials. In the present study, the analogue FL9, based on the amphibian AMP fallaxin, was studied to elucidate its mode of action and antibacterial activity against the human pathogen Staphylococcus aureus. Our data showed that FL9 may have a dual mode of action against S. aureus. At concentrations around the MIC, FL9 bound DNA, inhibited DNA synthesis and induced the SOS DNA damage response, whereas at concentrations above the MIC the interaction between S. aureus and FL9 led to membrane disruption. The antibacterial activity of the peptide was maintained over a wide range of NaCl and MgCl(2) concentrations and at alkaline pH, while it was compromised by acidic pH and exposure to serum. Furthermore, at subinhibitory concentrations of FL9, S. aureus responded by increasing the expression of two major virulence factor genes, namely the regulatory rnaIII and hla, encoding α-haemolysin. In addition, the S. aureus-encoded natural tolerance mechanisms included peptide cleavage and the addition of positive charge to the cell surface, both of which minimized the antimicrobial activity of FL9. Our results add new information about FL9 and its effect on S. aureus, which may aid in the future development of analogues with improved therapeutic potential.
抗生素耐药性病原体的迅速增加引发了更多的健康担忧，因此迫切需要新型抗菌剂。抗菌肽（AMPs）已从多种生物体中分离出来，是一类非常有前景的新型抗菌剂。在本研究中，对基于两栖动物抗菌肽fallaxin的类似物FL9进行了研究，以阐明其作用模式以及对人类病原体金黄色葡萄球菌的抗菌活性。我们的数据表明，FL9对金黄色葡萄球菌可能具有双重作用模式。在MIC浓度左右，FL9结合DNA，抑制DNA合成并诱导SOS DNA损伤反应，而在高于MIC的浓度下，金黄色葡萄球菌与FL9之间的相互作用导致膜破坏。该肽的抗菌活性在广泛的NaCl和MgCl₂浓度范围内以及碱性pH条件下得以维持，而在酸性pH和暴露于血清时则受到损害。此外，在FL9的亚抑制浓度下，金黄色葡萄球菌通过增加两个主要毒力因子基因的表达做出反应，这两个基因分别是调控性的rnaIII和编码α-溶血素的hla。此外，金黄色葡萄球菌编码的天然耐受机制包括肽裂解和细胞表面正电荷的添加，这两者都使FL9的抗菌活性降至最低。我们的结果为FL9及其对金黄色葡萄球菌的影响增添了新信息，这可能有助于未来开发具有更高治疗潜力的类似物。
