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LetB结构揭示跨细菌包膜的脂质运输通道添加时间:2020-05-03 11:02
  

本期文章:《细胞》:Volume 181 Issue 3

2020年4月30日,美国纽约大学医学院的Gira Bhabha、Damian C. Ekiert等研究人员合作在《细胞》杂志发表论文。他们的最新工作报道了LetB结构,从而揭示了一个跨越细菌包膜的脂质运输隧道。

研究人员报道了大肠杆菌MCE(Mammalian Cell Entry)蛋白LetB的冷冻电镜结构,分辨率约为3.5Å,从而揭示了一个约0.6兆道尔顿的复合物,其由七个堆叠的环组成,中央疏水通道的长度足以跨越周质。

 

脂质在通道内结合,表明其充当脂质运输的途径。在打开和关闭状态下的冷冻电镜结构显示出动态的通道,并对门控或底物转运有影响。

 

这些结果建立了一个模型,即LetB在两层膜之间建立了物理联系,并为脂质跨周质的转运创造了疏水途径。

 

据悉,革兰氏阴性细菌被磷脂和脂多糖组成的外膜所包围,该外膜起着屏障的作用,并且对抗生素产生抗药性。介导跨周质运输磷脂的系统,例如MCE转运蛋白,尚未得到很好的表征。 

 

附:英文原文

Title: LetB Structure Reveals a Tunnel for Lipid Transport across the Bacterial Envelope

Author: Georgia L. Isom, Nicolas Coudray, Mark R. MacRae, Collin T. McManus, Damian C. Ekiert, Gira Bhabha

Issue&Volume: 2020/04/30

Abstract: Gram-negative bacteria are surrounded by an outer membrane composed of phospholipidsand lipopolysaccharide, which acts as a barrier and contributes to antibiotic resistance.The systems that mediate phospholipid trafficking across the periplasm, such as MCE(Mammalian Cell Entry) transporters, have not been well characterized. Our ~3.5 cryo-EM structure of the E. coli MCE protein LetB reveals an ~0.6 megadalton complex that consists of seven stackedrings, with a central hydrophobic tunnel sufficiently long to span the periplasm.Lipids bind inside the tunnel, suggesting that it functions as a pathway for lipidtransport. Cryo-EM structures in the open and closed states reveal a dynamic tunnellining, with implications for gating or substrate translocation. Our results supporta model in which LetB establishes a physical link between the two membranes and createsa hydrophobic pathway for the translocation of lipids across the periplasm.

DOI: 10.1016/j.cell.2020.03.030

Source: https://www.cell.com/cell/fulltext/S0092-8674(20)30322-6

期刊信息

Cell:《细胞》,创刊于1974年。隶属于细胞出版社,最新IF:36.216

官方网址:https://www.cell.com/

投稿链接:https://www.editorialmanager.com/cell/default.aspx