Gram-negative bacteria possess a dual-membrane envelope, which provides defense against environmental assault, as well as formidable resistance against antibiotics. Lipopolysaccharide (LPS) is the primary lipid component in the outermost membrane leaflet of most Gram-negative bacteria, and plays critical roles in cell envelope formation. Newly synthesized LPS at the cytoplasmic side of the inner membrane is flipped across the inner membrane and pushed across the periplasm by two ATP-binding cassette transporters, MsbA and LptB2FGC, respectively. Both transporters represent promising targets for developing new classes of antibiotics. In this review, we discuss recent advances in understanding the mechanism of LPS translocation driven by MsbA and LptB2FGC, with a particular focus on new findings from structural studies.

中文翻译：

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ABC 转运蛋白 MsbA 和 LptB2FGC 驱动的脂多糖易位的高分辨率视图。

革兰氏阴性细菌具有双膜包膜，可抵御环境攻击，并对抗生素具有强大的抵抗力。脂多糖 (LPS) 是大多数革兰氏阴性菌最外层膜小叶中的主要脂质成分，在细胞包膜形成中起关键作用。在内膜的细胞质侧新合成的 LPS 被翻转穿过内膜并分别被两个 ATP 结合盒式转运蛋白 MsbA 和 LptB2FGC 推动穿过周质。两种转运蛋白都代表了开发新型抗生素的有希望的目标。在这篇综述中，我们讨论了在理解由 MsbA 和 LptB2FGC 驱动的 LPS 易位机制方面的最新进展，特别关注结构研究的新发现。