Laboratory of Microbial Technology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
J Am Chem Soc. 2012 Feb 29;134(8):3687-90. doi: 10.1021/ja300007h. Epub 2012 Feb 17.
Ring A of nukacin ISK-1, which is also present in different type-A(II) lantibiotics, resembles a lipid II-binding motif (TxS/TxD/EC, x denotes undefined residues) similar to that present in mersacidin (type-B lantibiotics), which suggests that nukacin ISK-1 binds to lipid II as a docking molecule. Results from our experiments on peptidoglycan precursor (UDP-MurNAc-pp) accumulation and peptide antagonism assays clearly indicated that nukacin ISK-1 inhibits cell-wall biosynthesis, accumulating lipid II precursor inside the cell, and the peptide activity can be repressed by lipid I and lipid II. Interaction analysis of nukacin ISK-1 and different ring A variants with lipid II revealed that nukacin ISK-1 and nukacin D13E (a more active variant) have a high affinity (K(D) = 0.17 and 0.19 μM, respectively) for lipid II, whereas nukacin D13A (a less active variant) showed a lower affinity, and nukacin C14S (a negative variant lacking the ring A structure) exhibited no interaction. Therefore, on the basis of the structural similarity and positional significance of the amino acids in this region, we concluded that nukacin ISK-1 binds lipid II via its ring A region and may lead to the inhibition of cell-wall biosynthesis.
环 A 的 nukacin ISK-1，它也存在于不同类型的 A(II) 类细菌素，类似于 mersacidin（B 型细菌素）中存在的脂质 II 结合基序（TxS/TxD/EC，x 表示未定义的残基），这表明 nukacin ISK-1 作为 docking 分子结合脂质 II。我们关于肽聚糖前体（UDP-MurNAc-pp）积累和肽拮抗测定的实验结果清楚地表明，nukacin ISK-1 抑制细胞壁生物合成，在细胞内积累脂质 II 前体，并且可以通过脂质 I 和脂质 II 抑制肽活性。nukacin ISK-1 与不同环 A 变体与脂质 II 的相互作用分析表明，nukacin ISK-1 和 nukacin D13E（一种更活跃的变体）与脂质 II 具有高亲和力（K(D) = 0.17 和 0.19 μM，分别），而 nukacin D13A（一种不活跃的变体）表现出较低的亲和力，而 nukacin C14S（一种缺少环 A 结构的阴性变体）则没有相互作用。因此，基于该区域中氨基酸的结构相似性和位置意义，我们得出结论，nukacin ISK-1 通过其环 A 区域结合脂质 II，并可能导致细胞壁生物合成的抑制。
