Phosphatidylglycerol Is the Lipid Donor for Synthesis of Phospholipid-Linked Enterobacterial Common Antigen.
Phosphatidylglycerol Is the Lipid Donor for Synthesis of Phospholipid-Linked Enterobacterial Common Antigen.
复制标题
磷脂酰甘油是合成磷脂连接肠杆菌共同抗原的脂质供体。
DOI：
10.1128/jb.00403-22
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发表时间：
2023
影响因子：
3.2
通讯作者：
Mitchell,AngelaM
中科院分区：
文献类型：
--
作者：
Morris,KinseyN;Mitchell,AngelaM
革兰氏阴性外膜（OM）是一种不对称的双分子层，磷脂在其内小叶，主要是脂多糖（LPS）在其外小叶，许多抗生素在很大程度上是不渗透的。InEnterobacterales(如。（如埃希氏菌、沙门氏菌、克雷伯氏菌和耶尔森氏菌），OM的外层小叶也含有磷酸甘油连接肠杆菌共同抗原（ECAPG）。该分子由保守的ECA碳水化合物组成，通过磷酸二酯键与磷酸二酰基甘油（DAG-P）相连。ecapg有助于OM的渗透性屏障，模型表明它可能改变LPS分子在OM中的包装。在这里，我们研究了在大肠杆菌K-12中，由连接到类异戊二烯载体的ECA前体合成ECAPG的反应，以确定为ECAPG提供DAG-P片段的脂质供体。通过磷脂生物合成基因的过表达，我们观察到增加磷脂酰甘油（PG）水平的改变增加了ECAPG的合成，而降低PG水平的改变减少了ECAPG的合成。我们发现，在能够合成ECAPG但不能合成其他形式的ECA的菌株中，PG水平的降低会导致额外的生长缺陷，这可能是由于ECA前体在类异戊二烯载体上的积累抑制了肽聚糖的生物合成。我们的研究结果表明，ecapg可以在没有其他主要磷脂（磷脂酰乙醇胺和心磷脂）的情况下合成。总的来说，这些结果最终证明PG是合成ECAPG的脂质供体，并为产生ECAPG的反应提供了关键的见解。此外，这些结果提供了一个有趣的相似脂蛋白酰化，也使用PG作为其DAG供体。革兰氏阴性外膜是防止抗生素进入细胞的渗透性屏障。然而，外膜生物发生途径是小分子发育的靶点。在这里，我们研究了肠杆菌共同抗原（ECA）的一种形式的合成，ECAPG，发现于肠杆菌(如：如埃希氏菌、沙门氏菌和克雷伯氏菌)。ecapg由与磷酸二酰基甘油相连的保守的ECA碳水化合物单元组成，ECA是一个磷脂头基。从聚合的ECA前体形成这种分子的反应细节尚不清楚。我们确定提供磷脂部分的脂质供体是磷脂酰甘油。了解外膜成分（如ecapg）的合成为开发增加外膜通透性的分子提供了机会，扩大了治疗革兰氏阴性感染的抗生素的可用性。
The Gram-negative outer membrane (OM) is an asymmetric bilayer with phospholipids in its inner leaflet and mainly lipopolysaccharide (LPS) in its outer leaflet and is largely impermeable to many antibiotics. InEnterobacterales(e.g., Escherichia, Salmonella, Klebsiella, and Yersinia), the outer leaflet of the OM also contains phosphoglyceride-linked enterobacterial common antigen (ECAPG). This molecule consists of the conserved ECA carbohydrate linked to diacylglycerol-phosphate (DAG-P) through a phosphodiester bond. ECAPGcontributes to the OM permeability barrier and modeling suggests that it may alter the packing of LPS molecules in the OM. Here, we investigate, in Escherichia coli K-12, the reaction synthesizing ECAPGfrom ECA precursor linked to an isoprenoid carrier to identify the lipid donor that provides the DAG-P moiety to ECAPG. Through overexpression of phospholipid biosynthesis genes, we observed alterations expected to increase levels of phosphatidylglycerol (PG) increased the synthesis of ECAPG, whereas alterations expected to decrease levels of PG decreased the synthesis of ECAPG. We discovered depletion of PG levels in strains that could synthesize ECAPG, but not other forms of ECA, causes additional growth defects, likely due to the buildup of ECA precursor on the isoprenoid carrier inhibiting peptidoglycan biosynthesis. Our results demonstrate ECAPGcan be synthesized in the absence of the other major phospholipids (phosphatidylethanolamine and cardiolipin). Overall, these results conclusively demonstrate PG is the lipid donor for the synthesis of ECAPGand provide a key insight into the reaction producing ECAPG. In addition, these results provide an interesting parallel to lipoprotein acylation, which also uses PG as its DAG donor.IMPORTANCEThe Gram-negative outer membrane is a permeability barrier preventing cellular entry of antibiotics. However, outer membrane biogenesis pathways are targets for small molecule development. Here, we investigate the synthesis of a form of enterobacterial common antigen (ECA), ECAPG, found in the outer membrane ofEnterobacterales(e.g., Escherichia, Salmonella, and Klebsiella). ECAPGconsists of the conserved ECA carbohydrate unit linked to diacylglycerol-phosphate—ECA is a phospholipid headgroup. The details of the reaction forming this molecule from polymerized ECA precursor are unknown. We determined the lipid donor providing the phospholipid moiety is phosphatidylglycerol. Understanding the synthesis of outer membrane constituents such as ECAPGprovides the opportunity for development of molecules to increase outer membrane permeability, expanding the antibiotics available to treat Gram-negative infections.