Antonenko Yuri N, Khailova Ljudmila S, Rokitskaya Tatyana I, Nosikova Ekaterina S, Nazarov Pavel A, Luzina Ol'ga A, Salakhutdinov Nariman F, Kotova Elena A
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
Biochim Biophys Acta Bioenerg. 2019 Apr 1;1860(4):310-316. doi: 10.1016/j.bbabio.2019.01.005. Epub 2019 Jan 30.
Usnic acid (UA), an old antibiotic and one of the first described mitochondrial uncouplers, has demonstrated many beneficial activities, such as antimicrobial, antiviral, antitumour and anti-inflammatory properties. Here, we performed a thorough investigation of effects of usnic acid and its analogues on artificial planar bilayer lipid membrane (BLM), rat liver mitochondria and bacteria. Surprisingly enough, all of the three hydroxyl groups of UA appeared to be involved in its proton-shuttling activity on BLM. We ascribed this fact to an ability of UA to form complexes with calcium ions, aiding it in cycling protons across the membrane. Actually, the addition of calcium ions markedly stimulated the UA-induced electrical current across BLM. By using the calcium ionophore A23187, we proved the involvement of calcium ions in the UA uncoupling action on isolated rat liver mitochondria. The calcium-chelating property of UA was demonstrated here by the method of extracting metal ions into a hydrophobic phase. Modification of any of the hydroxyl groups in UA dramatically reduced not only the UA-induced current across BLM and the UA-mediated calcium extraction, but also the uncoupling activity of UA in mitochondria and the inhibiting effect of UA on the growth of Bacillus subtilis. The ability of UA to cause dissipation of membrane potential in isolated liver mitochondria and bacterial cells was shown here for the first time. In view of the data obtained, the protonophoric activity of UA is considered to make a significant contribution to its antibacterial action.
松萝酸（UA）是一种古老的抗生素，也是最早被描述的线粒体解偶联剂之一，已显示出许多有益活性，如抗菌、抗病毒、抗肿瘤和抗炎特性。在此，我们对松萝酸及其类似物对人工平面双层脂质膜（BLM）、大鼠肝线粒体和细菌的影响进行了全面研究。令人惊讶的是，UA的所有三个羟基似乎都参与了其在BLM上的质子穿梭活性。我们将这一事实归因于UA与钙离子形成复合物的能力，有助于其跨膜循环质子。实际上，添加钙离子显著刺激了UA诱导的跨BLM电流。通过使用钙离子载体A23187，我们证明了钙离子参与了UA对分离的大鼠肝线粒体的解偶联作用。此处通过将金属离子萃取到疏水相的方法证明了UA的钙螯合特性。UA中任何一个羟基的修饰不仅显著降低了UA诱导的跨BLM电流和UA介导的钙萃取，还降低了UA在线粒体中的解偶联活性以及UA对枯草芽孢杆菌生长的抑制作用。此处首次展示了UA导致分离的肝线粒体和细菌细胞膜电位耗散的能力。鉴于所获得的数据，UA的质子载体活性被认为对其抗菌作用有重大贡献。
