OmpA, a protein commonly found in the outer membrane of Gram-negative bacteria, has served as a paradigm for the study of β-barrel proteins for several decades. In Escherichia coli, OmpA was previously reported to form complexes with RcsF, a surface-exposed lipoprotein that triggers the Rcs stress response when damage occurs in the outer membrane and the peptidoglycan. How OmpA interacts with RcsF and whether this interaction allows RcsF to reach the surface has remained unclear. Here, we integrated in vivo and in vitro approaches to establish that RcsF interacts with the C-terminal, periplasmic domain of OmpA, not with the N-terminal β-barrel, thus implying that RcsF does not reach the bacterial surface via OmpA. Our results suggest a novel function for OmpA in the cell envelope: OmpA competes with the inner membrane protein IgaA, the downstream Rcs component, for RcsF binding across the periplasm, thereby regulating the Rcs response.

中文翻译：

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定义 OmpA 在 Rcs 应激反应中的功能

OmpA 是一种常见于革兰氏阴性菌外膜中的蛋白质，几十年来一直是研究 β-桶蛋白的范例。在大肠杆菌中，先前有报道称 OmpA 与 RcsF 形成复合物，RcsF 是一种表面暴露的脂蛋白，当外膜和肽聚糖发生损伤时会触发 Rcs 应激反应。OmpA 如何与 RcsF 相互作用以及这种相互作用是否允许 RcsF 到达表面仍不清楚。在这里，我们整合了体内和体外方法来确定 RcsF 与 OmpA 的 C 端周质域相互作用，而不是与 N 端 β-桶相互作用，因此暗示 RcsF 不会通过 OmpA 到达细菌表面。我们的结果表明 OmpA 在细胞包膜中的一种新功能：OmpA 与内膜蛋白 IgaA 竞争，