Daptomycin is a lipopeptide antibiotic that binds and permeabilizes the cell membranes of Gram-positive bacteria. Membrane permeabilization requires both calcium and phosphatidylglycerol (PG) in the target membrane, and it correlates with the formation of an oligomer that likely comprises eight subunits, which are evenly distributed between the two membrane leaflets. In both bacterial cells and model membranes, changes in the fatty acyl composition of the membrane phospholipids can prevent permeabilization. We here used liposomes to study the effect of phospholipids containing oleoyl and other fatty acyl residues on daptomycin activity, and made the following observations: (1) Oleic acid residues inhibited permeabilization when part not only of PG, but also of other phospholipids (PC or cardiolipin). (2) When included in an otherwise daptomycin-susceptible lipid mixture, even 10% of dioleoyl lipid (DOPC) can strongly inhibit permeabilization. (3) The inhibitory effect of fatty acyl residues appears to correlate more with their chain length than with unsaturation. (4) Under all conditions tested, permeabilization coincided with octamer formation, whereas tetramers were observed on membranes that were not permeabilized. Overall, our findings further support the notion that the octamer is indeed the functional transmembrane pore, and that fatty acyl residues may prevent pore formation by preventing the alignment of tetramers across the two membrane leaflets.

达托霉素是一种脂肽抗生素，可结合并透化革兰氏阳性细菌的细胞膜。膜透化需要靶膜中的钙和磷脂酰甘油（PG），并且与低聚物的形成相关，该低聚物可能包含八个亚基，它们均匀地分布在两个膜小叶之间。在细菌细胞和模型膜中，膜磷脂的脂肪酰基组成的变化都可以防止通透性。我们在这里使用脂质体来研究含油酰基和其他脂肪酰基残基的磷脂对达托霉素活性的影响，并得出以下观察结果：（1）当残油不仅是PG的一部分，而且是其他磷脂（PC或PC的一部分）时，油酸残基也会抑制通透性。心磷脂）。（2）当包含在达托霉素敏感的脂质混合物中时，甚至10％的油酰脂质（DOPC）也可以强烈抑制通透性。（3）脂肪酰基残基的抑制作用似乎与其链长相关，而不与不饱和键相关。（4）在所有测试条件下，通透性均与八聚物形成同时发生，而在未通透的膜上观察到四聚体。总体而言，我们的发现进一步支持了八聚体确实是功能性跨膜孔的观点，并且脂肪酰基残基可能会通过阻止四聚体跨过两个膜小叶的排列而阻止孔的形成。（3）脂肪酰基残基的抑制作用似乎与其链长相关，而不与不饱和键相关。（4）在所有测试条件下，通透性均与八聚物形成同时发生，而在未通透的膜上观察到四聚体。总体而言，我们的发现进一步支持了八聚体确实是功能性跨膜孔的观点，并且脂肪酰基残基可能会通过阻止四聚体跨过两个膜小叶的排列而阻止孔的形成。（3）脂肪酰基残基的抑制作用似乎与其链长相关，而不与不饱和键相关。（4）在所有测试条件下，通透性均与八聚物形成同时发生，而在未通透的膜上观察到四聚体。总体而言，我们的发现进一步支持了八聚体确实是功能性跨膜孔的观点，并且脂肪酰基残基可能会通过阻止四聚体跨过两个膜小叶的排列而阻止孔的形成。