Accumulation of Phosphatidic Acid Increases Vancomycin Resistance in Escherichia coli
Accumulation of Phosphatidic Acid Increases Vancomycin Resistance in Escherichia coli
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DOI：
10.1128/jb.01876-14
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发表时间：
2014-09-01
影响因子：
3.2
通讯作者：
Silhavy, Thomas J.
中科院分区：
文献类型：
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作者：
Sutterlin, Holly A.;Zhang, Sisi;Silhavy, Thomas J.
在革兰氏阴性细菌中，脂多糖 (LPS) 有助于形成坚固的外膜渗透屏障，防止抗生素等有毒分子进入。 LPTD（LPS 运输和组装机制的 β 桶组件）的突变会损害 LPS 组装并导致抗生素敏感性增加。在这里，我们报告了罕见的万古霉素耐药抑制剂，可改善 lptD 突变子集的屏障功能。我们发现分析的所有七个抑制因子都映射到必需基因 cdsA，该基因负责磷脂生物合成中磷脂酸转化为 CDP-二酰基甘油。这些 cdsA 突变会导致部分功能丧失，并且如预期的那样，会积累磷脂酸。我们表明，这种抑制并不局限于导致外膜生物发生缺陷的突变，而是这些 cdsA 突变导致万古霉素耐药性普遍增加，即使在野生型细胞中也是如此。我们使用遗传学和四极杆飞行时间 (Q-TOF) 液相色谱-质谱 (LC-MS) 表明，通过 cdsA 突变以外的方式积累磷脂酸也会增加对万古霉素的耐药性。我们认为，磷脂酸水平的增加会改变外膜的物理性质，从而阻止万古霉素进入周质，从而阻碍其到达靶标（肽聚糖细胞壁合成所需的中间体）。
In Gram-negative bacteria, lipopolysaccharide (LPS) contributes to the robust permeability barrier of the outer membrane, preventing entry of toxic molecules such as antibiotics. Mutations in lptD, the beta-barrel component of the LPS transport and assembly machinery, compromise LPS assembly and result in increased antibiotic sensitivity. Here, we report rare vancomycin-resistant suppressors that improve barrier function of a subset of lptD mutations. We find that all seven suppressors analyzed mapped to the essential gene cdsA, which is responsible for the conversion of phosphatidic acid to CDP-diacylglycerol in phospholipid biosynthesis. These cdsA mutations cause a partial loss of function and, as expected, accumulate phosphatidic acid. We show that this suppression is not confined to mutations that cause defects in outer membrane biogenesis but rather that these cdsA mutations confer a general increase in vancomycin resistance, even in a wild-type cell. We use genetics and quadrupole time of flight (Q-TOF) liquid chromatography-mass spectrometry (LC-MS) to show that accumulation of phosphatidic acid by means other than cdsA mutations also increases resistance to vancomycin. We suggest that increased levels of phosphatidic acid change the physical properties of the outer membrane to impede entry of vancomycin into the periplasm, hindering access to its target, an intermediate required for the synthesis of the peptidoglycan cell wall.