Mechanism of substrate recognition by bacterial lipoprotein transport equipment

细菌脂蛋白是膜相关蛋白的一个子集，在N-末端半胱氨酸与脂类共价修饰。脂蛋白修饰的最后一步，即载脂蛋白的N-酰化，是由LNT介导的。当LolCDE在缺乏主要外膜脂蛋白LPP或将LPP与肽聚糖交联的转肽酶缺失的菌株中过量生产时，可以构建LNT缺失菌株。我们发现LolCDE对载脂蛋白的亲和力很低，因此LolCDE的过度表达是其释放和分选到外膜的必要条件。

Bacterial lipoproteins represent a subset of membrane-associated proteins that are covalently modified with lipids at the N-terminal cysteine. The final step of lipoprotein modification, N-acylation of apolipoproteins, is mediated by Lnt. lnt null strains could be constructed when LolCDE was overproduced in strains lacking either the major outer membrane lipoprotein Lpp or transpeptidases that cross-link Lpp with peptidoglycan. We revealed that affinity of LolCDE for apolipoprotein is very low, and therefore overexpression of LolCDE is required for its release and sorting to the outer membrane.