Abstract：
Persister cells constitute a bacterial subpopulation able to survive to high concentrations of antibiotics. This phenotype is temporary and reversible, and thus could be involved in the recurrence of infections and emergence of antibiotic resistance. To better understand how persister cells survive to such high antibiotic concentration, we examined changes in their lipid composition. We thus compared the lipidome of Acinetobacter baumannii ATCC 19606T persister cells formed under ciprofloxacin treatment with the lipidome of control cells grown without antibiotic. Using matrix assisted laser desorption ionisation-Fourier transform ion cyclotron resonance mass spectrometry, we observed a higher abundance of short chains and secondary chains without hydroxylation for lipid A in persister cells. Using liquid chromatography-tandem mass spectrometry, we found that persister cells produced particular phosphatidylglycerols, as LPAGPE and PAGPE, but also lipids with particular acyl chains containing additional hydroxyl group or uncommon di-unsaturation on C18 and C16 acyl chains. In order to determine the impact of these multiple lipidome modifications on membrane fluidity, fluorescence anisotropy assays were performed. They showed an increase of rigidity for the membrane of persister cells, inducing likely a decrease membrane permeability to protect cells during dormancy. Finally, we highlighted that A. baumannii persister cells also produced particular wax esters, composed of two fatty acids and a fatty diol. These uncommon storage lipids are key metabolites allowing a rapid bacterial regrow when antibiotic pressure disappears. These overall changes in persister lipidome may constitute new therapeutic targets to combat these particular dormant cells.
摘要：
耐受细胞构成能够在高浓度抗生素下存活的细菌亚群。这种表型是暂时的和可逆的，因此可能参与感染的复发和抗生素耐药性的出现。为了更好地了解持久性细胞如何在如此高的抗生素浓度下存活，我们检查了它们的脂质成分的变化。因此，我们将环丙沙星处理下形成的鲍曼不动杆菌ATCC19606T稳定细胞的脂质组与不含抗生素的对照细胞的脂质组进行了比较。使用基质辅助激光解吸电离-傅立叶变换离子回旋共振质谱，我们观察到在保留细胞中脂质A的短链和二级链的丰度更高，没有羟基化。使用液相色谱-串联质谱法，我们发现持久细胞产生特定的磷脂酰甘油，如LPAGPE和PAGPE，还有在C18和C16酰基链上具有含有额外羟基或不常见二不饱和基的特定酰基链的脂质。为了确定这些多重脂质修饰对膜流动性的影响，进行荧光各向异性测定。它们显示出持久细胞膜的刚度增加，在休眠期间诱导可能降低膜通透性以保护细胞。最后,我们强调鲍曼不动杆菌细胞也产生特定的蜡酯，由两种脂肪酸和一种脂肪二醇组成。这些不常见的储存脂质是关键代谢产物，当抗生素压力消失时，细菌会迅速再生。持久脂质组的这些总体变化可能构成新的治疗靶标，以对抗这些特定的休眠细胞。
