van den Hooven H W, Rollema H S, Siezen R J, Hilbers C W, Kuipers O P
Department of Biophysical Chemistry, NIZO (Netherlands Institute for Dairy Research), Kernhemseweg 2, 6718 ZB Ede, The Netherlands.
Biochemistry. 1997 Nov 18;36(46):14137-45. doi: 10.1021/bi9713106.
The antimicrobial membrane-interacting polypeptide nisin is a prominent member of the lantibiotic family, the members of which contain thioether-bridged residues called lanthionines. To gain insight into the complex biosynthesis and the structure/function relationship of lantibiotics, the final intermediate in the biosynthesis of nisin A was studied by nuclear magnetic resonance spectroscopy. In aqueous solution the leader peptide part of this precursor adopts predominantly a random coil structure, as does the synthetic leader peptide itself. The spatial structure of the fully modified nisin part of the precursor is similar to that of nisin in water. The leader peptide part does not interact with the nisin part of the precursor molecule. Thus, these two parts of the precursor do not influence each other's conformation significantly. The conformation of the precursor was also studied while complexed to micelles of dodecylphosphocholine, mimicking the primary target of the antimicrobial activity of nisin, i.e. the cytoplasmic membrane. The location of the molecule relative to the micelles was investigated by using micelle-inserted spin-labeled 5-doxylstearic acid. It was observed that the N-terminal half of the nisin part of the precursor interacts in a different way with micelles than does the corresponding part of mature nisin, whereas no significant differences were found for the C-terminal half of the nisin part. In this model system the leader peptide is in contact with the micelles. It is concluded that the strongly reduced in vivo activity of the precursor molecule relative to that of nisin is not caused by a difference in the spatial structure of nisin and of the corresponding part of precursor nisin in water or by a shielding of the membrane interaction surface of the nisin part of the precursor by the leader peptide. Probably a different interaction of the N-terminal part of the nisin region with membranes contributes to the low activity by preventing productive insertion. The residues of the leader peptide part just next to the nisin part are likely to contribute most to the low activity of the precursor.
抗微生物膜相互作用多肽乳链菌肽是羊毛硫抗生素家族的重要成员，该家族成员含有称为羊毛硫氨酸的硫醚桥连残基。为深入了解羊毛硫抗生素复杂的生物合成及其结构/功能关系，利用核磁共振光谱对乳链菌肽A生物合成的最终中间体进行了研究。在水溶液中，该前体的前导肽部分主要采用无规卷曲结构，合成的前导肽本身也是如此。前体完全修饰的乳链菌肽部分的空间结构与水中的乳链菌肽相似。前导肽部分不与前体分子的乳链菌肽部分相互作用。因此，前体的这两个部分不会显著影响彼此的构象。还研究了前体与十二烷基磷酸胆碱胶束复合时的构象，模拟了乳链菌肽抗菌活性的主要靶点，即细胞质膜。通过使用插入胶束的自旋标记5-脱氧硬脂酸研究了分子相对于胶束的位置。观察到前体乳链菌肽部分的N端一半与胶束的相互作用方式与成熟乳链菌肽的相应部分不同，而乳链菌肽部分的C端一半没有发现显著差异。在这个模型系统中，前导肽与胶束接触。得出的结论是，前体分子相对于乳链菌肽在体内活性的大幅降低，不是由于乳链菌肽和前体乳链菌肽相应部分在水中的空间结构差异，也不是由于前导肽对前体乳链菌肽部分膜相互作用表面的屏蔽。可能是乳链菌肽区域N端部分与膜的不同相互作用通过阻止有效插入导致了低活性。紧邻乳链菌肽部分的前导肽部分的残基可能对前体的低活性贡献最大。
