Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Japan.
Exploratory Research Laboratories, Tsukuba Research Institute, ONO Pharmaceutical Co., LTD, 17-2 Wadai, Tsukuba 300-4247, Japan.
J Biochem. 2018 Aug 1;164(2):93-102. doi: 10.1093/jb/mvy030.
Staphylococcus aureus bi-component pore-forming toxins consist of S- and F-components, and form hetero-octameric beta-barrel pores on target blood cell membranes. Among them, γ-haemolysin (Hlg2 and F-component of Luk (LukF)) and LukED (LukE and LukD) possess haemolytic activity, whereas the Panton-Valentine leukocidin (LukS-PV and LukF-PV) does not lyse human erythrocytes. Here, we focussed on four loop structures in the rim domain of S-component, namely loops -1, -2, -3 and -4, and found that replacement of Loop-4 in both Hlg2 and LukE with that of LukS-PV abolished their haemolytic activity. Furthermore, LukS-PV gained haemolytic activity by Loop-4 exchange with Hlg2 or LukE, suggesting that Loop-4 of these S-components determined erythrocyte specificity. LOOP-1 and -2 enhanced the erythrocytes-binding ability of both components. Although Hlg2 and LukE recognize Duffy antigen receptor for chemokines on human erythrocytes, the ability of Loop-4 was not complementary between Hlg2 and LukE. Exchange of Hlg2 with LukE Loop-4 showed weaker activity than intact Hlg2, and LukE mutant with Hlg2 Loop-4 lost its haemolytic activity in combination of LukD. Interestingly, the haemolytic activities of these Loop-4 exchange mutants were affected by F-component, namely LukF enhanced haemolytic activities of these Hlg2 and LukE Loop-4 mutants, and also haemolytic activity of LukS-PV mutant with LukE Loop-4.
金黄色葡萄球菌双组分孔形成毒素由 S 组分和 F 组分组成，并在靶血细胞的细胞膜上形成异源八聚体β-桶状孔。其中，γ-溶血素（Hlg2 和 Luk 的 F 组分（LukF））和 LukED（LukE 和 LukD）具有溶血活性，而 Panton-Valentine 白细胞毒素（LukS-PV 和 LukF-PV）不裂解人红细胞。在这里，我们专注于 S 组分边缘域中的四个环结构，即环-1、-2、-3 和 -4，并发现 Hlg2 和 LukE 中的环-4 被 LukS-PV 取代，其溶血活性被消除。此外，LukS-PV 通过与 Hlg2 或 LukE 的 Loop-4 交换获得了溶血活性，表明这些 S 组分的 Loop-4 决定了红细胞的特异性。Loop-1 和 -2 增强了两种成分与红细胞的结合能力。尽管 Hlg2 和 LukE 识别人红细胞上的趋化因子 Duffy 抗原受体，但 Hlg2 和 LukE 之间的 Loop-4 能力并不互补。Hlg2 与 LukE Loop-4 的交换显示出比完整 Hlg2 弱的活性，并且具有 Hlg2 Loop-4 的 LukE 突变体在与 LukD 结合时失去了溶血活性。有趣的是，这些 Loop-4 交换突变体的溶血活性受到 F 组分的影响，即 LukF 增强了这些 Hlg2 和 LukE Loop-4 突变体的溶血活性，以及具有 LukE Loop-4 的 LukS-PV 突变体的溶血活性。
