Institute for Photonics and Advanced Sensing (IPAS), School of Biological Sciences, The University of Adelaide, South Australia, 5005, Australia.
Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, NSW, 2522, Australia.
Chemistry. 2018 Aug 6;24(44):11325-11331. doi: 10.1002/chem.201801734. Epub 2018 Jul 19.
The human sliding clamp (PCNA) controls access to DNA for many proteins involved in DNA replication and repair. Proteins are recruited to the PCNA surface by means of a short, conserved peptide motif known as the PCNA-interacting protein box (PIP-box). Inhibitors of these essential protein-protein interactions may be useful as cancer therapeutics by disrupting DNA replication and repair in these highly proliferative cells. PIP-box peptide mimetics have been identified as a potentially rapid route to potent PCNA inhibitors. Here we describe the rational design and synthesis of the first PCNA peptidomimetic ligands, based on the high affinity PIP-box sequence from the natural PCNA inhibitor p21. These mimetics incorporate covalent i,i+4 side-chain/side-chain lactam linkages of different lengths, designed to constrain the peptides into the 3 -helical structure required for PCNA binding. NMR studies confirmed that while the unmodified p21 peptide had little defined structure in solution, mimetic ACR2 pre-organized into 3 -helical structure prior to interaction with PCNA. ACR2 displayed higher affinity binding than most known PIP-box peptides, and retains the native PCNA binding mode, as observed in the co-crystal structure of ACR2 bound to PCNA. This study offers a promising new strategy for PCNA inhibitor design for use as anti-cancer therapeutics.
人类滑动夹（PCNA）控制着许多参与 DNA 复制和修复的蛋白质对 DNA 的访问。蛋白质通过一种短的、保守的肽基序（称为 PCNA 相互作用蛋白盒（PIP-box））被募集到 PCNA 表面。这些必需的蛋白质-蛋白质相互作用的抑制剂可能通过破坏这些高度增殖细胞中的 DNA 复制和修复而作为癌症治疗剂有用。已经确定 PIP-box 肽模拟物是一种潜在的快速途径，可以获得有效的 PCNA 抑制剂。在这里，我们描述了基于天然 PCNA 抑制剂 p21 的高亲和力 PIP-box 序列的第一个 PCNA 肽模拟物配体的合理设计和合成。这些模拟物包含不同长度的共价 i,i+4 侧链/侧链内酰胺键，旨在将肽约束成 PCNA 结合所需的 3 -螺旋结构。NMR 研究证实，虽然未修饰的 p21 肽在溶液中几乎没有确定的结构，但模拟物 ACR2 在与 PCNA 相互作用之前预先组织成 3 -螺旋结构。ACR2 显示出比大多数已知的 PIP-box 肽更高的亲和力结合，并且保留了与 PCNA 结合的天然模式，如 ACR2 与 PCNA 结合的共晶结构中所观察到的。这项研究为作为抗癌治疗剂的 PCNA 抑制剂设计提供了一个很有前途的新策略。
