Abstract：
Epilancin 15X is a lantibiotic that has an antimicrobial activity in the nanomolar concentration range towards Staphylococcus simulans. Such low MICs usually imply that these peptides employ a mechanism of action (MoA) involving high affinity targets. Here we studied this MoA by using epilancin 15X\'s ability to dissipate the membrane potential of intact S. simulans cells. These membrane depolarization assays showed that treatment of the bacteria by antibiotics known to affect the bacterial cell wall synthesis pathway decreased the membrane depolarization effects of epilancin 15X. Disruption of the Lipid II cycle in intact bacteria using several methods led to a decrease in the activity of epilancin 15X. Antagonism-based experiments on 96-well plate and agar diffusion plate pointed towards a possible interaction between epilancin 15X and Lipid II and this was confirmed by Circular Dichroism (CD) based experiments. However, this interaction did not lead to a detectable effect on either carboxyfluorescein (CF) leakage or proton permeability. All experiments point to the involvement of a phosphodiester-containing target within a polyisoprene-based biosynthesis pathway, yet the exact identity of the target remains obscure so far.
摘要：
Epilancin15X是一种羊毛硫抗生素，在纳摩尔浓度范围内对模拟葡萄球菌具有抗菌活性。这种低MIC通常意味着这些肽采用涉及高亲和力靶标的作用机制(MoA)。在这里，我们通过使用epilancin15X的耗散完整S.simulans细胞的膜电位的能力来研究这种MoA。这些膜去极化实验表明，通过已知会影响细菌细胞壁合成途径的抗生素对细菌的处理降低了epilancin15X的膜去极化作用。使用几种方法破坏完整细菌中的脂质II循环，导致epilancin15X的活性降低。在96孔板和琼脂扩散板上进行的基于拮抗作用的实验指出了Epirancin15X和LipidII之间可能的相互作用，这已通过基于圆形二色性（CD）的实验得到证实。然而,这种相互作用不会对羧基荧光素（CF）泄漏或质子渗透性产生可检测的影响。所有实验都指出，在基于聚异戊二烯的生物合成途径中，含有磷酸二酯的靶标参与。然而，到目前为止，目标的确切身份仍然不清楚。
