Engineering protein stability with atomic precision in a monomeric miniprotein.
Engineering protein stability with atomic precision in a monomeric miniprotein.
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DOI：
10.1038/nchembio.2380
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发表时间：
2017-07
影响因子：
14.8
通讯作者：
Woolfson DN
中科院分区：
文献类型：
--
作者：
Baker EG;Williams C;Hudson KL;Bartlett GJ;Heal JW;Porter Goff KL;Sessions RB;Crump MP;Woolfson DN
微型蛋白质简化了蛋白质折叠的问题，允许分解稳定蛋白质结构的力。在这里，我们描述了PPα-TYR，一种设计的肽，包含由多聚脯氨酸-II螺旋支撑的α螺旋。PPα-TYR是一种水溶性单体，在中点展开温度(TM)为39°C的情况下协同展开。PPα-TYR的核磁共振结构显示，与设计的酪氨酸侧链之间的Pro残基对接。PPα的稳定性对芳香族残基很敏感：用苯丙氨酸取代酪氨酸，即将三个暴露在溶剂中的羟基转变为质子，使Tm降至20°C。我们将此归因于芳香环和Pro环之间失去CH-π相互作用，我们通过用非蛋白生成侧链取代芳香族残基来探测这一点。在对天然蛋白质结构的分析中，我们发现与其他含Pro的蛋白质对相比，更倾向于Pro-酪氨酸相互作用，并且在富含Pro的配体与SH3及其类似结构域之间具有重要生物学意义的络合物中存在丰富的CH-π相互作用。
Miniproteins simplify the protein-folding problem, allowing the dissection of forces that stabilize protein structures. Here we describe PPα-Tyr, a designed peptide comprising an α helix buttressed by a polyproline-II helix. PPα-Tyr is water soluble, monomeric, and unfolds cooperatively with a midpoint unfolding temperature (TM) of 39 °C. NMR structures of PPα-Tyr reveal proline residues docked between tyrosine side chains as designed. The stability of PPα is sensitive to the aromatic residue: replacing tyrosine by phenylalanine, i.e. changing three solvent-exposed hydroxyl groups to protons, reduces the TM to 20 °C. We attribute this to the loss of CH–π interactions between the aromatic and proline rings, which we probe by substituting the aromatic residues with non-proteinogenic side chains. In analyses of natural protein structures we find a preference for proline-tyrosine interactions over other proline-containing pairs, and abundant CH–π interactions in biologically important complexes between proline-rich ligands and SH3 and similar domains.