Guangdong Provincial Engineering Research Center of Molecular Imaging, the Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong, 519000, China.
Guangdong-Hong Kong-Macao University Joint Laboratory of Interventional Medicine, the Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong, 519000, China.
Nat Commun. 2023 Nov 21;14(1):7571. doi: 10.1038/s41467-023-43469-8.
Cis-peptide bonds are rare in proteins, and building blocks less favorable to the trans-conformer have been considered destabilizing. Although proline tolerates the cis-conformer modestly among all amino acids, for collagen, the most prevalent proline-abundant protein, all peptide bonds must be trans to form its hallmark triple-helix structure. Here, using host-guest collagen mimetic peptides (CMPs), we discover that surprisingly, even the cis-enforcing peptoid residues (N-substituted glycines) form stable triple-helices. Our interrogations establish that these peptoid residues entropically stabilize the triple-helix by pre-organizing individual peptides into a polyproline-II helix. Moreover, noting that the cis-demanding peptoid residues drastically reduce the folding rate, we design a CMP whose triple-helix formation can be controlled by peptoid cis-trans isomerization, enabling direct targeting of fibrotic remodeling in myocardial infarction in vivo. These findings elucidate the principles of peptoid cis-trans isomerization in protein folding and showcase the exploitation of cis-amide-favoring residues in building programmable and functional peptidomimetics.
顺式肽键在蛋白质中很少见，人们认为构建块不利于形成反式构象会使蛋白质不稳定。虽然脯氨酸在所有氨基酸中对顺式构象的容忍度适中，但对于最常见的富含脯氨酸的胶原蛋白来说，所有的肽键都必须是反式的，才能形成其标志性的三螺旋结构。在这里，我们使用主体-客体胶原蛋白模拟肽（CMP），令人惊讶的是，即使是强制形成顺式构象的肽模拟物（N-取代甘氨酸）也能形成稳定的三螺旋。我们的研究结果表明，这些肽模拟物通过将单个肽预先组织成聚脯氨酸-II 螺旋，在熵上稳定了三螺旋。此外，我们注意到，需要形成顺式构象的肽模拟物残基极大地降低了折叠速率，因此我们设计了一种 CMP，其三螺旋的形成可以通过肽模拟物的顺反异构化来控制，从而能够直接靶向体内心肌梗死后的纤维化重塑。这些发现阐明了肽模拟物顺反异构化在蛋白质折叠中的原理，并展示了在构建可编程和功能性肽模拟物时利用顺式酰胺偏好残基的潜力。
