The Extracellular Adherence Protein (Eap) from Staphylococcus aureus is a potent inhibitor of the classical and lectin pathways of the complement system. Previous studies have shown that Eap binds with nanomolar affinity to complement component C4b and prevents C4b binding the pro-protease, C2, thereby inhibiting formation of the pro-C3 convertase shared by the classical and lectin pathways (Woehl et al. in J Immunol 193:6161–6171, 2014). The C4b-binding and complement-inhibitory properties of Eap from S. aureus strain Mu50 lie within the two C terminal-most Eap domains (i.e. Eap34) (Woehl et al. J Immunol 193:6161–6171, 2014). Interestingly, Eap34 binds C4b with an apparent K_D that is nearly 100-fold tighter than that of either Eap3 or Eap4 alone (Woehl et al. in Protein Sci 26:1595–1608, 2017). This suggests that linking these two domains into a single molecule is a significant determinant of Eap function. To better understand this property at the structural level, we undertook a solution NMR study of the ~ 23 kDa Eap34 protein. In this communication, we report that greater than 98% of the total non-proline backbone residues have been assigned. These data have been deposited in the BMRB database under the accession number 50210.

金黄色葡萄球菌的细胞外粘附蛋白 (Eap)是补体系统经典途径和凝集素途径的有效抑制剂。先前的研究表明，Eap 以纳摩尔级的亲和力与补体成分 C4b 结合并阻止 C4b 与蛋白酶原 C2 结合，从而抑制经典途径和凝集素途径共有的前 C3 转化酶的形成（Woehl 等人，J Immunol 193 :6161–6171, 2014)。来自金黄色葡萄球菌菌株 Mu50的 Eap 的 C4b 结合和补体抑制特性位于两个 C 末端最末端的 Eap 结构域（即 Eap34）内（Woehl 等人 J Immunol 193:6161–6171, 2014）。_{有趣的是，Eap34 以明显的 K D}结合 C4b这比单独的 Eap3 或 Eap4 紧近 100 倍（Woehl 等人在 Protein Sci 26:1595–1608, 2017）。这表明将这两个结构域连接成一个分子是 Eap 功能的重要决定因素。为了在结构水平上更好地理解这一特性，我们对约 23 kDa Eap34 蛋白进行了溶液 NMR 研究。在本次交流中，我们报告超过 98% 的非脯氨酸骨架残基已被分配。这些数据已保存在 BMRB 数据库中，登录号为 50210。