Effect of divalent cations on the structure of the antibiotic daptomycin
Effect of divalent cations on the structure of the antibiotic daptomycin
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DOI：
10.1007/s00249-007-0227-2
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发表时间：
2008-04-01
影响因子：
2
通讯作者：
Straus, Suzana K.
中科院分区：
文献类型：
--
作者：
Ho, Steven W.;Jung, David;Straus, Suzana K.
达托霉素是一种环阴离子脂肽抗生素，其三维结构最近通过溶液态核磁共振（NMR）得到了解决（Ball et al. 2004; Jung et al. 2004; Rotondi and Gierasch 2005），它需要钙来发挥作用。迄今为止，二价阳离子（如Ca2+或Mg2+）之间相互作用的确切性质尚未得到充分表征。然而，有人认为，钙+加入达托霉素在1:1摩尔比诱导聚集。此外，有研究表明，某些残基，如Asp3和Asp7，对活性至关重要（Grunewald et al. 2004; Kopp et al. 2006），也可能对Ca2+结合很重要（Jung et al. 2004）。在这项工作中，我们尝试：(1)使用分析超离心进一步查明Ca2+如何影响达托霉素的结构/寡聚化；(2)基于一维C-13核磁共振光谱和分子动力学（MD）模拟，确定是否存在特定的钙结合位点。离心结果表明，在Ca2+与达托霉素的摩尔比为1:1的情况下，达托霉素形成了14 ~ 16个单体的胶束。13c NMR数据表明，钙的加入对Trp1和Kyn13残基有显著影响，表明钙在该区域结合，或者这些残基可能对寡聚化很重要。最后，分子动力学模拟结果表明，钙结合后达托霉素的构象变化可能并不像最初提出的那样显著。对二价阳离子Mg2+也进行了类似的研究。讨论了这些结果对达托霉素生物学功能的意义。
Daptomycin, a cyclic anionic lipopeptide antibiotic, whose three-dimensional structure was recently solved using solution state NMR ( Ball et al. 2004; Jung et al. 2004; Rotondi and Gierasch 2005), requires calcium for function. To date, the exact nature of the interaction between divalent cations, such as Ca2+ or Mg2+, has not been fully characterized. It has, however, been suggested that addition of Ca2+ to daptomycin in a 1: 1 molar ratio induces aggregation. Moreover, it has been suggested that certain residues, e. g. Asp3 and Asp7, which are essential for activity (Grunewald et al. 2004; Kopp et al. 2006), may also be important for Ca2+ binding ( Jung et al. 2004). In this work, we have tried: ( 1) to further pinpoint how Ca2+ affects daptomycin structure/ oligomerization using analytical ultracentrifugation; and ( 2) to determine whether a specific calcium binding site exists, based on one-dimensional C-13 NMR spectra and molecular dynamics ( MD) simulations. The centrifugation results indicated that daptomycin formed micelles of between 14 and 16 monomers in the presence of a 1: 1 molar ratio of Ca2+ and daptomycin. The 13 C NMR data indicated that addition of calcium had a significant effect on the Trp1 and Kyn13 residues, indicating that either calcium binds in this region or that these residues may be important for oligomerization. Finally, the molecular dynamics simulation results indicated that the conformational change of daptomycin upon calcium binding might not be as significant as originally proposed. Similar studies on the divalent cation Mg2+ are also presented. The implication of these results for the biological function of daptomycin is discussed.