Mechanism of substrate recognition by bacterial lipoprotein transport equipment

细菌脂蛋白代表在N-末端半胱氨酸处用脂质共价修饰的膜相关蛋白的子集。脂蛋白修饰的最后一步，载脂蛋白的N-酰化，由Lnt介导。当LolCDE在缺乏主要外膜脂蛋白Lpp或使Lpp与肽聚糖交联的转肽酶的菌株中过量产生时，可以构建lnt无效菌株。我们发现LolCDE对载脂蛋白的亲和力非常低，因此LolCDE的过表达是其释放和分选到外膜所必需的。

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.