Strongly altered receptor binding properties in PP and NPY chimeras are accompanied by changes in structure and membrane binding
Strongly altered receptor binding properties in PP and NPY chimeras are accompanied by changes in structure and membrane binding
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DOI：
10.1021/bi0501232
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发表时间：
2005-06-28
期刊：
影响因子：
2.9
通讯作者：
Zerbe, O
中科院分区：
文献类型：
--
作者：
Lerch, M;Kamimori, H;Zerbe, O
神经肽Y（NPY）和胰多肽（PP）是神经肽Y激素家族的成员。它们以非常不同的亲和力与Y受体结合：PP对Y-4受体具有高度选择性，而NPY对Y-1、Y-2和Y-5受体亚型具有最高亲和力。将NPY片段19-23引入PP导致对Y-1和Y-2受体亚型的亲和力增加，而将该片段从PP交换到NPY导致对所有受体亚型的亲和力大幅降低。PP在溶液中显示出非常稳定的结构，其中N末端反向折叠到C末端α-螺旋上（所谓的PP折叠）。NPY的螺旋不太稳定，N末端在溶液中自由扩散。然而，该区段的交换不改变溶液中嵌合肽的PP-折叠倾向。用于模拟膜结合物质的磷脂胶束结合肽的结构显示分离成更灵活的N-末端区域和明确定义的α-螺旋区域。将[19-23]-pNPY片段引入hPP导致α-螺旋的N-末端延伸，现在从Pro（14）而不是Met（17）开始。相反，在[（19-23）hPP]-pNPY中观察到截短的螺旋，从Leu（17）而不是Ala（14）开始。所有肽均显示出与中性膜的中等结合亲和力（通过表面等离子体共振测定，K-天冬氨酸在1.7至6.8 x 10（4）mol（-1）范围内），结合差异最可能与Arg-19（pNPY）与Glu-23（hPP）的交换有关。因此，嵌合体与其亲本肽之间的受体结合特性的差异最有可能是由于胶束结合肽的构象变化。
Neuropeptide Y (NPY) and the pancreatic polypeptide (PP) are members of the neuropeptide Y family of hormones. They bind to the Y receptors with very different affinities: Whereas PP is highly selective for the Y-4 receptor, NPY displays highest affinites for Y-1, Y-2, and Y-5 receptor subtypes. Introducing the NPY segment 19-23 into PP leads to an increase in affinity at the Y-1 and Y-2 receptor subtypes whereas the exchange of this segment from PP into NPY leads to a large decrease in affinity at all receptor subtypes. PP displays a very stable structure in solution, with the N terminus being back-folded onto the C-terminal alpha-helix (the so-called PP-fold). The helix of NPY is less stable and the N terminus is freely diffusing in solution. The exchange of this segment, however, does not alter the PP-fold propensities of the chimeric peptides in solution. The structures of the phospholipid micelle-bound peptides serving to mimic the membrane-bound species display segregation into a more flexible N-terminal region and a well-defined alpha-helical region. The introduction of the [19-23]-pNPY segment into hPP leads to an N-terminal extension of the alpha-helix, now starting at Pro(14) instead of Met(17). In contrast, a truncated helix is observed in [(19-23)hPP]-pNPY, starting at Leu(17) instead of Ala(14). All peptides display moderate binding affinities to neutral membranes (K-assoc in the range of 1.7 to 6.8 x 10(4) mol(-1) as determined by surface plasmon resonance) with the differences in binding being most probably related to the exchange of Arg-19 (pNPY) by Glu-23 (hPP). Differences in receptor binding properties between the chimeras and their parental peptides are therefore most likely due to changes in the conformation of the micelle-bound peptides.