The First Structure of a Lantibiotic Immunity Protein, SpaI from Bacillus subtilis, Reveals a Novel Fold
The First Structure of a Lantibiotic Immunity Protein, SpaI from Bacillus subtilis, Reveals a Novel Fold
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DOI：
10.1074/jbc.m112.401620
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发表时间：
2012-10-12
影响因子：
4.8
通讯作者：
Woehnert, Jens
中科院分区：
文献类型：
--
作者：
Christ, Nina A.;Bochmann, Sophie;Woehnert, Jens
羊毛硫抗生素是肽衍生的抗生素，其通过与脂质II的相互作用和细菌膜中脂质II依赖性孔的形成来抑制革兰氏阳性菌的生长。由于它们的一般作用模式，革兰氏阳性生产菌株需要表达免疫蛋白（LanI蛋白）以保护免受其自身的羊毛硫抗生素的侵害。关于在分子水平上保护生产菌株免受其自身lantibiotic侵害的免疫机制知之甚少。到目前为止，还没有关于任何LanI蛋白的结构的报道。我们解决了SpaI的结构，LanI蛋白从枯草杆菌素生产菌株枯草芽孢杆菌ATCC 6633。SpaI是一种16.8-kDa脂蛋白，通过共价二酰基甘油锚附着在细胞质膜外侧。SpaI与ABC转运蛋白SpaFEG一起保护B。枯草杆菌膜从枯草杆菌蛋白插入。15 kDa的生物活性的C-末端片段的溶液-NMR结构揭示了一种新的折叠。我们还表明，不存在于此C-末端片段的前20个N-末端氨基酸在溶液中是非结构化的，并且是与脂质膜相互作用所必需的。此外，生长试验表明，这20个N-末端残基对于Spa I介导的免疫是重要的，但很可能不是可能的枯草杆菌蛋白结合位点的一部分。我们的发现是理解B免疫机制的第一步。特别是枯草芽孢杆菌，以及一般的其它羊毛硫抗生素生产菌株。
Lantibiotics are peptide-derived antibiotics that inhibit the growth of Gram-positive bacteria via interactions with lipid II and lipid II-dependent pore formation in the bacterial membrane. Due to their general mode of action the Gram-positive producer strains need to express immunity proteins (LanI proteins) for protection against their own lantibiotics. Little is known about the immunity mechanism protecting the producer strain against its own lantibiotic on the molecular level. So far, no structures have been reported for any LanI protein. We solved the structure of SpaI, a LanI protein from the subtilin producing strain Bacillus subtilis ATCC 6633. SpaI is a 16.8-kDa lipoprotein that is attached to the outside of the cytoplasmic membrane via a covalent diacylglycerol anchor. SpaI together with the ABC transporter SpaFEG protects the B. subtilis membrane from subtilin insertion. The solution-NMR structure of a 15-kDa biologically active C-terminal fragment reveals a novel fold. We also demonstrate that the first 20 N-terminal amino acids not present in this C-terminal fragment are unstructured in solution and are required for interactions with lipid membranes. Additionally, growth tests reveal that these 20 N-terminal residues are important for the immunity mediated by SpaI but most likely are not part of a possible subtilin binding site. Our findings are the first step on the way of understanding the immunity mechanism of B. subtilis in particular and of other lantibiotic producing strains in general.