Axial Hydrogen at C7 Position and Bumpy Tetracyclic Core Markedly Reduce Sterol's Affinity to Amphotericin B in Membrane

作者：Nakagawa Yasuo; Umegawa Yuichi; Nonomura Kenichi; Matsushita Naohiro; Takano Tetsuro; Tsuchikawa Hiroshi; Hanashima Shinya; Oishi Tohru; Matsumori Nobuaki^*; Murata Michio

来源：Biochemistry, 2015, 54(2): 303-312.

DOI：10.1021/bi5012942

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 Delta 7-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 Delta 5, Delta 7, and Delta 9 positions. Intermolecular distance measurements by C-13{F-19} 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 Delta 5-sterol (2, 6) and the protruded A-ring of Delta 5,7,9-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 alpha-face of sterol alicycle interacts with the flat macrolide structure of AmB.

• 出版日期2015-1-20