The Escherichia coli cellulose synthase subunit G (BcsG) is a Zn2+-dependent phosphoethanolamine transferase
The Escherichia coli cellulose synthase subunit G (BcsG) is a Zn2+-dependent phosphoethanolamine transferase
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DOI：
10.1074/jbc.ra119.011668
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发表时间：
2020-05-01
影响因子：
4.8
通讯作者：
Weadge, Joel T.
中科院分区：
文献类型：
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作者：
Anderson, Alexander C.;Burnett, Alysha J. N.;Weadge, Joel T.
细菌生物膜是产生粘附基质的细胞群落。胞外多糖是该基质的关键结构组分，并且是由多种微生物产生的生物膜的组装和结构所需的。人类细菌病原体大肠杆菌和肠道沙门氏菌产生主要由胞外多糖磷酸乙醇胺（pEtN）纤维素组成的生物膜基质。一旦被认为仅由未衍生化的纤维素组成，这些基质中存在的pEtN修饰就涉及生物膜的整体结构和完整性。然而，对纤维素胞外多糖的pEtN衍生化的潜在机制的理解仍然是难以捉摸的。细菌纤维素合成酶亚基G（BcsG）是一个预测的内膜？局部金属酶，已被提出催化pEtN基团从膜磷脂转移到纤维素。在这里，我们提出了证据表明来自大肠杆菌的BcsG的C末端结构域。coli（EcBcsG（？N））在体外起磷酸乙醇胺转移酶的作用，对纤维素材料具有底物偏好性。EcBcsG（？N）揭示其属于碱性磷酸酶超家族，在其活性中心含有Zn 2+离子，并且在结构上类似于赋予革兰氏阴性细菌中的粘菌素抗性的表征酶。根据我们的结构研究，我们提出了一个功能互补实验，在E。coli AR 3110中表达，表明BcsG C-末端结构域的活性对生物膜的完整性至关重要。此外，我们的研究结果建立了一个类似的，但不同的活性位点结构和催化机制之间共享BcsG和粘菌素抗性酶。
Bacterial biofilms are cellular communities that produce an adherent matrix. Exopolysaccharides are key structural components of this matrix and are required for the assembly and architecture of biofilms produced by a wide variety of microorganisms. The human bacterial pathogens Escherichia coli and Salmonella enterica produce a biofilm matrix composed primarily of the exopolysaccharide phosphoethanolamine (pEtN) cellulose. Once thought to be composed of only underivatized cellulose, the pEtN modification present in these matrices has been implicated in the overall architecture and integrity of the biofilm. However, an understanding of the mechanism underlying pEtN derivatization of the cellulose exopolysaccharide remains elusive. The bacterial cellulose synthase subunit G (BcsG) is a predicted inner membrane?localized metalloenzyme that has been proposed to catalyze the transfer of the pEtN group from membrane phospholipids to cellulose. Here we present evidence that the C-terminal domain of BcsG from E. coli (EcBcsG(?N)) functions as a phosphoethanolamine transferase in vitro with substrate preference for cellulosic materials. Structural characterization of EcBcsG(?N) revealed that it belongs to the alkaline phosphatase superfamily, contains a Zn2+ ion at its active center, and is structurally similar to characterized enzymes that confer colistin resistance in Gram-negative bacteria. Informed by our structural studies, we present a functional complementation experiment in E. coli AR3110, indicating that the activity of the BcsG C-terminal domain is essential for integrity of the pellicular biofilm. Furthermore, our results established a similar but distinct active-site architecture and catalytic mechanism shared between BcsG and the colistin resistance enzymes.