Artificial Chemokines: Combining Chemistry and Molecular Biology for the Elucidation of Interleukin-8 Functionality
Artificial Chemokines: Combining Chemistry and Molecular Biology for the Elucidation of Interleukin-8 Functionality
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DOI：
10.1021/ja802453x
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发表时间：
2008-11-19
影响因子：
15
通讯作者：
Beck-Sickinger, Annette G.
中科院分区：
文献类型：
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作者：
David, Ralf;Guenther, Robert;Beck-Sickinger, Annette G.
我们如何理解单个部件或部分对复杂结构的贡献？回答这个问题的一个典型策略是模拟片段替换，然后在结构-活性研究中实现和调查由此产生的影响。对于蛋白质，这个问题通常通过定点诱变来解决。一种更普遍的方法是通过合理设计的分段来交换整个二级结构元素。为了证明这种可能性，我们鉴定了人类白细胞介素-8 (hIL-8) c端的α -螺旋。由于这种趋化因子具有四个保守的半胱氨酸残基，它可以很容易地通过连接策略改变。合成了一组能够形成两亲螺旋的不同片段来模拟c端α -螺旋。除了α -氨基酸序列外，还介绍了具有典型氨基酸侧链的非天然β(3)-氨基酸的低聚物。这种β -多肽形成螺旋，在手性和偶极子取向上与α -螺旋不同。半合成hIL-8蛋白的变异清楚地表明，准确的侧链取向比螺旋手性和偶极子取向更重要。具有β肽螺旋的嵌合蛋白的活性最完美地模仿了天然α -螺旋的侧链取向，与天然hIL-8的活性相当。像这样的概念可能是合成由大型人工二级结构元素组成的蛋白质的第一步。
How can we understand the contribution of individual parts or segments to complex structures? A typical strategy to answer this question is simulation of a segmental replacement followed by realization and investigation of the resulting effect in structure-activity studies. For proteins, this problem is commonly addressed by site-directed mutagenesis. A more general approach represents the exchange of whole secondary structure elements by rationally designed segments. For a demonstration of this possibility we identified the alpha-helix at the C-terminus of human interleukin-8 (hIL-8). Since this chemokine possesses four conserved cysteine residues, it can easily be altered by ligation strategies. A set of different segments, which are able to form amphiphilic helices, was synthesized to mimic the C-terminal alpha-helix. Beside sequences of alpha-amino acids, oligomers of non-natural beta(3)-amino acids with the side chains of canonical amino acids were introduced. Such beta-peptides form helices, which differ from the alpha-helix in handedness and dipole orientation. Variants of the semisynthetic hIL-8 proteins demonstrated clearly that the exact side chain orientation is of more importance than helix handedness and dipole orientation. The activity of a chimeric protein with a beta-peptide helix that mimics the side chain orientation of the native alpha-helix most perfectly is comparable to that of the native hIL-8. Concepts like this could be a first step toward the synthesis of proteins consisting of large artificial secondary structure elements.