Escherichia Coli LPS-transport protein LptA. Escherichia coli

Lipopolysaccharide (LPS) is the major constituent of the outer membrane (OM) of most Gram-negative bacteria, providing a barrier against antibiotics. LPS is synthesized at the inner membrane (IM), transported across the periplasm and assembled at the OM by the multiprotein Lpt complex. LptA is the periplasmic component of the Lpt complex, which bridges IM and OM and ferries LPS across the periplasm. How the cell co-ordinates the processes involved in OM biogenesis is not completely understood. We have generated a partial loss of function mutant in lptA, which exhibits increased sensitivity to antibiotics and isolated two classes of suppressors of this mutant. The analysis of the suppressors reveals different strategies adopted by the cell to overcome defects in LPS biogenesis.

脂多糖（Lipopolysaccharide, LPS）是大多数革兰氏阴性菌外膜（outer membrane, OM）的主要组成成分，可构成抵御抗生素的天然屏障。LPS在内膜（inner membrane, IM）中合成，经周质间隙转运，并由多蛋白Lpt复合物组装于外膜。LptA是Lpt复合物的周质组分，可桥连内膜与外膜，介导LPS跨周质间隙转运。目前学界尚未完全阐明细胞如何协调外膜生物发生相关的各项过程。本研究构建了lptA基因的部分功能丧失突变体，该突变体表现出抗生素敏感性升高；同时我们分离得到两类针对该突变体的抑制子。对这些抑制子的分析揭示了细胞用以克服LPS生物发生缺陷的不同策略。