Forsman Huamei, Winther Malene, Gabl Michael, Skovbakke Sarah Line, Boulay Francois, Rabiet Marie-Josèphe, Dahlgren Claes
Department of Rheumatology and Inflammation Research, University of Gothenburg, Sweden.
Department of Rheumatology and Inflammation Research, University of Gothenburg, Sweden; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
Biochim Biophys Acta. 2015 Jan;1853(1):192-200. doi: 10.1016/j.bbamcr.2014.10.021. Epub 2014 Oct 30.
Pathogenic Staphylococcus aureus strains produce N-formylmethionyl containing peptides, of which the tetrapeptide fMIFL is a potent activator of the neutrophil formyl peptide receptor 1 (FPR1) and the PSMα2 peptide is a potent activator of the closely related FPR2. Variants derived from these two peptide activators were used to disclose the structural determinants for receptor interaction. Removal of five amino acids from the C-terminus of PSMα2 gave rise to a peptide that had lost the receptor-independent neutrophil permeabilizing effect, whereas neutrophil activation capacity as well as its preference for FPR2 was retained. Shorter peptides, PSMα21-10 and PSMα21-5, activate neutrophils, but the receptor preference for these peptides was switched to FPR1. The fMIFL-PSM5-16 peptide, in which the N-terminus of PSMα21-16 was replaced by the sequence fMIFL, was a dual agonist for FPR1/FPR2, whereas fMIFL-PSM5-10 preferred FPR1 to FPR2. Further, an Ile residue was identified as a key determinant for interaction with FPR2. A chimeric receptor in which the cytoplasmic tail of FPR1 was replaced by the corresponding part of FPR2 lost the ability to recognize FPR1 agonists, but gained function in relation to FPR2 agonists. Taken together, our data demonstrate that the C-terminus of the PSMα2 peptide plays a critical role for its cytotoxicity, but is not essential for the receptor-mediated pro-inflammatory activity. More importantly, we show that the amino acids present in the C-terminus, which are not supposed to occupy the agonist-binding pocket in the FPRs, are of importance for the choice of receptor.
致病性金黄色葡萄球菌菌株会产生含N-甲酰甲硫氨酸的肽，其中四肽fMIFL是中性粒细胞甲酰肽受体1（FPR1）的强效激活剂，而PSMα2肽是密切相关的FPR2的强效激活剂。源自这两种肽激活剂的变体被用于揭示受体相互作用的结构决定因素。从PSMα2的C末端去除五个氨基酸后产生了一种肽，该肽失去了受体非依赖性的中性粒细胞通透作用，而保留了中性粒细胞激活能力及其对FPR2的偏好。较短的肽PSMα21-10和PSMα21-5可激活中性粒细胞，但这些肽对受体的偏好转变为FPR1。fMIFL-PSM5-16肽（其中PSMα21-16的N末端被序列fMIFL取代）是FPR1/FPR2的双重激动剂，而fMIFL-PSM5-10对FPR1的偏好高于FPR2。此外，一个异亮氨酸残基被确定为与FPR2相互作用的关键决定因素。一种嵌合受体，其中FPR1的胞质尾部被FPR2的相应部分取代，失去了识别FPR1激动剂的能力，但获得了与FPR2激动剂相关的功能。综上所述，我们的数据表明，PSMα2肽的C末端对其细胞毒性起关键作用，但对于受体介导的促炎活性并非必不可少。更重要的是，我们表明C末端存在的氨基酸（这些氨基酸不应该占据FPRs中的激动剂结合口袋）对于受体的选择很重要。
