SPECIFICITY OF DIFFUSION CHANNELS PRODUCED BY LAMBDA-PHAGE RECEPTOR PROTEIN OF ESCHERICHIA-COLI
SPECIFICITY OF DIFFUSION CHANNELS PRODUCED BY LAMBDA-PHAGE RECEPTOR PROTEIN OF ESCHERICHIA-COLI
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DOI：
10.1073/pnas.77.1.167
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发表时间：
1980-01-01
期刊：
影响因子：
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通讯作者：
NIKAIDO, H
中科院分区：
文献类型：
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作者：
LUCKEY, M;NIKAIDO, H
通过Triton X-100和EDTA萃取，Triton X-100柱层析，Triton X-100柱层析，Triton凝胶过滤交换胆酸盐，Sephacryl S-200胆酸盐柱层析，从E.ColiK-12细胞外膜上纯化了噬菌体受体Lambda。纯化的蛋白质似乎以几种寡聚体形式存在。在含有磷脂和脂多糖的重组囊泡的平衡保留试验中，LbmB蛋白对双糖具有通透性。在用来测量扩散速率的脂质体溶胀试验中，羊肉蛋白对各种底物的磷脂脂质体具有治疗作用。所获得的速率表明，羊肉蛋白促进的渗透是特异的，根据大小和结构区分底物。例如，麦芽糖扩散到脂质体的速度比蔗糖快40倍，比纤维二糖快约8倍，比麦芽七糖快约12倍。结果表明，羊肉蛋白形成了一个跨膜通道，其中包含一个或多个与溶质松散相互作用的部位。
The lamB protein, the receptor for phage .lambda., was purified from the outer membrane of E. coli K-12 by extraction with Triton X-100 and EDTA, chromatography on DEAE-Sephacel in Triton X-100, exchange of Triton for cholate by gel filtration, and chromatography on Sephacryl S-200 in cholate, NaCl and EDTA. The purified protein appeared to exist as several oligomeric species. In an equilibrium retention assay with reconstituted vesicles containing phospholipids and lipopolysaccharide, the lbmB protein conferred permeability for disaccharides. In a liposome swelling assay designed to measure diffusion rates, the lamB protein conferred pemeability to phospholipid liposomes for a variety of substrates. The rates obtained indicate the permeation facilitated by the lamB protein is specific, discriminating among substrates by both size and configuration. For example, maltose diffused into liposomes 40 times faster than sucrose, about 8 times faster than cellobiose, and about 12 times faster than maltoheptaose. The results suggest that the lamB protein forms a transmembrane channel containing a site (or sites) that loosely interacts with the solutes.