脂蛋白二酰甘油基转移酶(Lgt)催化革兰氏阴性细菌脂蛋白的生物发生的第一步,在细菌生长和发病机理中起着至关重要的作用。我们证明,临床尿路致病性大肠杆菌菌株中的Lgt耗竭会导致外膜透化,并增加对血清杀伤和抗生素的敏感性。重要的是,我们确定G2824是首次描述的Lgt抑制剂,它能在体外有效抑制Lgt生化活性,并且对野生型鲍曼不动杆菌和大肠杆菌菌株具有杀菌性.当缺失编码主要外膜脂蛋白的基因时,lpp,导致在下游II型信号肽酶的遗传消耗或药理学抑制后挽救细菌生长,LspA,在Lgt耗尽或用G2824治疗后,没有检测到这种生长的挽救。Lgt的抑制不会导致肽聚糖连接的Lpp在内膜中的显著积累。我们的数据验证了Lgt作为一种新的抗菌靶标,并表明,与脂蛋白生物合成和转运的下游步骤不同,Lgt的抑制可能对使细菌脂蛋白生物合成和转运抑制剂无效的最常见耐药机制之一不敏感。重要性随着多重耐药(MDR)细菌的新威胁不断增加,在过去的50年里,没有发现新的抗生素。虽然以前已经尝试过抑制脂蛋白生物合成(LspA)或转运(LolCDE)途径,导致抵抗的共同机制的出现阻碍了大多数努力,即,编码主要革兰氏阴性外膜脂蛋白lpp的基因的缺失。我们意想不到的发现,即Lgt的抑制对lpp缺失介导的抗性不敏感,揭示了细菌脂蛋白生物发生的复杂性以及与该基本外膜生物发生途径有关的相应酶,并可能指向该途径中的新抗菌靶标。
Lipoprotein diacylglyceryl transferase (
Lgt) catalyzes the first step in the biogenesis of Gram-negative bacterial lipoproteins which play crucial roles in bacterial growth and pathogenesis. We demonstrate that
Lgt depletion in a clinical uropathogenic Escherichia coli strain leads to permeabilization of the outer membrane and increased sensitivity to serum killing and antibiotics. Importantly, we identify G2824 as the first-described
Lgt inhibitor that potently inhibits
Lgt biochemical activity in vitro and is bactericidal against wild-type Acinetobacter baumannii and E. coli strains. While deletion of a gene encoding a major outer membrane lipoprotein, lpp, leads to rescue of bacterial growth after genetic depletion or pharmacologic inhibition of the downstream type II signal peptidase, LspA, no such rescue of growth is detected after Lgt depletion or treatment with G2824. Inhibition of
Lgt does not lead to significant accumulation of peptidoglycan-linked Lpp in the inner membrane. Our data validate Lgt as a novel antibacterial target and suggest that, unlike downstream steps in lipoprotein biosynthesis and transport, inhibition of Lgt may not be sensitive to one of the most common resistance mechanisms that invalidate inhibitors of bacterial lipoprotein biosynthesis and transport. IMPORTANCE As the emerging threat of multidrug-resistant (MDR) bacteria continues to increase, no new classes of antibiotics have been discovered in the last 50 years. While previous attempts to inhibit the lipoprotein biosynthetic (LspA) or transport (LolCDE) pathways have been made, most efforts have been hindered by the emergence of a common mechanism leading to resistance, namely, the deletion of the gene encoding a major Gram-negative outer membrane lipoprotein lpp. Our unexpected finding that inhibition of
Lgt is not susceptible to lpp deletion-mediated resistance uncovers the complexity of bacterial lipoprotein biogenesis and the corresponding enzymes involved in this essential outer membrane biogenesis pathway and potentially points to new antibacterial targets in this pathway.