Axial Hydrogen at C7 Position and Bumpy Tetracyclic Core Markedly Reduce Sterol’s Affinity to Amphotericin B in Membrane
Axial Hydrogen at C7 Position and Bumpy Tetracyclic Core Markedly Reduce Sterol’s Affinity to Amphotericin B in Membrane
复制标题
C7 位轴向氢和凹凸不平的四环核心显着降低了膜中甾醇对两性霉素 B 的亲和力
作者：
Nakagawa;Y.;Umegawa;Y.;Nonomura;K.;Matsushita;N.;Takano;T.;Tsuchikawa;H.;Hanashima;S.;Oishi;T.;Matsumori;N.;and Murata;M.
两性霉素B （AmB）与真菌麦角甾醇（Erg）的相互作用强于与哺乳动物胆固醇（Cho）的相互作用，AmB作为抗真菌药物的这一特性被认为是其对真菌具有选择性毒性的原因。然而，AmB识别甾醇之间结构差异的机制，特别是甾醇脂环部分的微小差异，在很大程度上是未知的。因此，为了研究AmB与甾醇核之间的相互作用模式，我们评估了AmB对具有不同脂环结构的各种甾醇的亲和力。离子通量测定和紫外光谱测量清楚地揭示了甾醇b环Δ7-double键与药物相互作用的重要性。AmB对在Δ5， Δ7和Δ9位置有双键的三烯甾醇具有较低的亲和力。通过13c {19F}旋转回声双共振（REDOR）测量分子间距离，发现AmB大环内酯环与Erg的类固醇核的接触比与Cho核的接触更紧密。构象分析表明，Δ5-sterol（2,6）的C7轴向氢原子和Δ5,7,9-甾醇（4,8）的突出a环在空间上阻碍了甾醇核的范德瓦尔斯表面与AmB的大环内酯之间的面对面接触。这些结果进一步表明，甾醇环α-面与AmB的扁平大环内酯结构相互作用。
The interaction of amphotericin B (AmB) with fungal ergosterol (Erg) is stronger than its interaction with mammalian cholesterol (Cho), and this property of AmB as an antifungal drug is thought to be responsible for its selective toxicity toward fungi. However, the mechanism by which AmB recognizes the structural differences between sterols, particularly minor difference in the sterol alicyclic portion, is largely unknown. Thus, to investigate the mode of interaction between AmB and the sterol core, we assessed the affinity of AmB to various sterols with different alicyclic structures. Ion flux assays and UV spectral measurements clearly revealed the importance of the Δ7-double bond of the sterol B-ring for interaction with the drug. AmB showed lower affinity for triene sterols, which have double bonds at the Δ5, Δ7, and Δ9 positions. Intermolecular distance measurements by13C{19F} rotational echo double resonance (REDOR) revealed that the AmB macrolide ring is in closer contact with the steroid core of Erg than it is with the Cho core in the membrane. Conformational analysis suggested that an axial hydrogen atom at C7 of Δ5-sterol (2,6) and the protruded A-ring of Δ5,7,9-sterol (4,8) sterically hampered face-to-face contact between the van der Waals surface of the sterol core and the macrolide of AmB. These results further suggest that the α-face of sterol alicycle interacts with the flat macrolide structure of AmB.