Toward Understanding the Outer Membrane Uptake of Small Molecules by Pseudomonas aeruginosa
Toward Understanding the Outer Membrane Uptake of Small Molecules by Pseudomonas aeruginosa
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DOI：
10.1074/jbc.m113.463570
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发表时间：
2013-04-26
影响因子：
4.8
通讯作者：
van den Berg, Bert
中科院分区：
文献类型：
--
作者：
Eren, Elif;Parkin, Jamie;van den Berg, Bert
由于小分子通过外膜（OM）通道进入革兰氏阴性菌，因此了解OM转运对于合理设计改进的和新的抗生素至关重要。在人类病原体铜绿假单胞菌中，大多数小分子被外膜羧酸盐通道（Occ）蛋白摄取，其可分为两个不同的亚家族，OccD和OccK。在这里，我们表征OCC蛋白属于这两个亚科介导的底物转运。OccK 2-葡萄糖醛酸共晶体结构的测定的基础上，我们确定的通道残基是必不可少的底物运输。我们进一步表明，通道的孔隙区域是刚性的OccK亚家族和高度动态的OccD亚家族。我们还表明，底物羧酸基团与基本阶梯的中心残基相互作用，一排精氨酸和赖氨酸残基，导致和远离通道收缩处的结合位点。此外，基本梯残基的重要性对应于它们的保守程度。最后，我们通过将整个家族的原型OccD 1从碱性氨基酸特异性通道转换为偏好带负电荷氨基酸的通道来应用所产生的见解。
Because small molecules enter Gram-negative bacteria via outer membrane (OM) channels, understanding OM transport is essential for the rational design of improved and new antibiotics. In the human pathogen Pseudomonas aeruginosa, most small molecules are taken up by outer membrane carboxylate channel (Occ) proteins, which can be divided into two distinct subfamilies, OccD and OccK. Here we characterize substrate transport mediated by Occ proteins belonging to both subfamilies. Based on the determination of the OccK2-glucuronate co-crystal structure, we identify the channel residues that are essential for substrate transport. We further show that the pore regions of the channels are rigid in the OccK subfamily and highly dynamic in the OccD subfamily. We also demonstrate that the substrate carboxylate group interacts with central residues of the basic ladder, a row of arginine and lysine residues that leads to and away from the binding site at the channel constriction. Moreover, the importance of the basic ladder residues corresponds to their degree of conservation. Finally, we apply the generated insights by converting the archetype of the entire family, OccD1, from a basic amino acid-specific channel into a channel with a preference for negatively charged amino acids.