Stability of loops in the structure of lactose permease.
Stability of loops in the structure of lactose permease.
复制标题
乳糖通透酶结构中环的稳定性。
DOI：
10.1021/bi049000s
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Yeagle,PhilipL
中科院分区：
文献类型：
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作者：
Bennett,Michael;Yeagle,JamesA;Maciejewski,Mark;Ocampo,James;Yeagle,PhilipL
肽片段的结构分析提供了有用的信息，从螺旋束（最多7个跨膜片段）构建的完整的膜蛋白的二级结构。将这些结果与最近的X射线晶体学结果进行比较，结果表明片段结构与完整蛋白质结构之间存在一致性。大肠杆菌乳糖通透酶（lac Y）提供了一个机会，以测试一个更大的膜蛋白的假设。Lac Y含有由11个环连接的12个跨膜片段的束。研究了11个片段，每个片段对应于该蛋白质中的一个环。其中五个片段在溶液中形成了由多维核磁共振确定的定义结构。四个肽形成转角，并且一个肽揭示了其中一个跨膜螺旋的末端。这些结果表明，螺旋束中的一些环通过短程相互作用而稳定，特别是在较小的束中，并且这种内在稳定的环可能有助于蛋白质的稳定性并影响折叠途径。在大的整合膜蛋白中可以发现更大的构象灵活性。
Structural analysis of peptide fragments has provided useful information on the secondary structure of integral membrane proteins built from a helical bundle (up to seven transmembrane segments). Comparison of those results to recent X-ray crystallographic results showed agreement between the structures of the fragments and the structures of the intact proteins. Lactose permease ofEscherichia coli(lac Y) offers an opportunity to test that hypothesis on a substantially larger integral membrane protein. Lac Y contains a bundle of 12 transmembrane segments connected by 11 loops. Eleven segments, each corresponding to one of the loops in this protein, were studied. Five of these segments form defined structures in solution as determined by multidimensional nuclear magnetic resonance. Four peptides form turns, and one peptide reveals the end of one of the transmembrane helices. These results suggest that some loops in helical bundles are stabilized by short-range interactions, particularly in smaller bundles, and such intrinsically stable loops may contribute to protein stability and influence the pathway of folding. Greater conformational flexibility may be found in large integral membrane proteins.