广泛的特点紧密低聚糖绑定在麦芽糖糊精运输/化学感应受体的高分辨率结构。
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Quiocho FA, Spurlino JC, Rodseth勒
广泛的特点紧密低聚糖绑定在麦芽糖糊精运输/化学感应受体的高分辨率结构。
结构。1997年8月15日,5 (8):997 - 1015。
- PubMed ID
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9309217 (在PubMed]
- 文摘
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背景:主动运输过程的执行一个至关重要的功能细胞,维持细胞内稳态和允许访问的营养。麦芽糊精/ maltose-binding蛋白(MBP);米(r) = 40 k)是一个作为一个初始的高亲和性受体蛋白质绑定组件maltooligosaccharides主动转运系统的细菌。MBP还参与对maltooligosaccharides趋化性。MBP,特定的细胞质膜蛋白之间的相互作用启动主动转运或趋化性。为了获得新的理解的MBP的函数,尤其是它的多功能性绑定不同的线性和环状低聚糖与类似的紧密联系,我们已经进行高分辨率x射线分析三个oligosaccharide-bound结构。结果:MBP的结构包裹着麦芽糖、麦芽三糖和maltotetraose精制高分辨率(1.67 - 1.8)。这些结构提供细节在原子水平的低聚糖绑定的许多特性。结构揭示埋和表面结合位点和显示之间的差异的重要性,氢键和范德华相互作用,特别是那些带来芳香残渣堆积。见解的结构可塑性提供蛋白质、亲和力、绑定特异性α/β异头偏好和低聚糖的长度。此外,展示不同的构象结构,可以通过内部的低聚糖复杂。 CONCLUSIONS: MBP has a two-domain structure joined by a hinge-bending region which contains the substrate-binding groove. The bound maltooligosaccharides have a ribbon-like structure: the edges of the ribbon are occupied by polar hydroxyl groups and the flat surfaces are composed of nonpolar patches of the sugar ring faces. The polar groups and nonpolar patches are heavily involved in forming hydrogen bonds and van der Waals contacts, respectively, with complimentary residues in the groove. Hinge-bending between the two domains enables the participation of both domains in the binding and sequestering of the oligosaccharides. Changes in the subtle contours of the binding site allow binding of maltodextrins of varying length with similarly high affinities. The fact that the three bound structures are essentially identical ensures productive interaction with the oligomeric membrane proteins, which are distinct for transport and chemotaxis.