Crystal structures of bacterial lipoprotein localization factors, LolA and LolB
Crystal structures of bacterial lipoprotein localization factors, LolA and LolB
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DOI：
10.1093/emboj/cdg324
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发表时间：
2003-07-01
期刊：
影响因子：
11.4
通讯作者：
Miki, K
中科院分区：
文献类型：
--
作者：
Takeda, K;Miyatake, H;Miki, K
在N-末端具有脂质修饰的半胱氨酸的脂蛋白取决于在位置2的残基而位于大肠杆菌的内膜或外膜上。在革兰氏阴性菌中，五种参与脂蛋白分选和膜定位的Lol蛋白是高度保守的。我们确定了一个周质伴侣，LolA，和外膜脂蛋白受体，LolB的晶体结构。尽管它们的氨基酸序列不同，但LolA和LolB的结构彼此惊人地相似。两者都有一个由未封闭的β桶和α-螺旋盖组成的疏水腔。空腔代表脂蛋白的脂质部分的可能结合位点。这两种蛋白质之间的详细结构差异提供了对脂蛋白从LolA到LolB和从LolB到外膜的能量不依赖性转移的分子机制的重要见解。此外，从不同的晶体形式确定的LolA和LolB的结构揭示了关于脂蛋白的缔合和解离的不同的结构动力学。结果进行了讨论的背景下，目前的模型脂蛋白转移从内到外膜通过亲水性环境。
Lipoproteins having a lipid-modified cysteine at the N-terminus are localized on either the inner or the outer membrane of Escherichia coli depending on the residue at position 2. Five Lol proteins involved in the sorting and membrane localization of lipoprotein are highly conserved in Gram-negative bacteria. We determined the crystal structures of a periplasmic chaperone, LolA, and an outer membrane lipoprotein receptor, LolB. Despite their dissimilar amino acid sequences, the structures of LolA and LolB are strikingly similar to each other. Both have a hydrophobic cavity consisting of an unclosed beta barrel and an alpha-helical lid. The cavity represents a possible binding site for the lipid moiety of lipoproteins. Detailed structural differences between the two proteins provide significant insights into the molecular mechanisms underlying the energy-independent transfer of lipoproteins from LolA to LolB and from LolB to the outer membrane. Furthermore, the structures of both LolA and LolB determined from different crystal forms revealed the distinct structural dynamics regarding the association and dissociation of lipoproteins. The results are discussed in the context of the current model for the lipoprotein transfer from the inner to the outer membrane through a hydrophilic environment.