Abstract 1532: Exploring structural differences between antagonistic peptides for the development of orally bioavailable PCSK9 inhibitors
Abstract 1532: Exploring structural differences between antagonistic peptides for the development of orally bioavailable PCSK9 inhibitors
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摘要 1532：探索拮抗肽之间的结构差异，以开发口服生物可利用的 PCSK9 抑制剂
DOI：
10.1016/j.jbc.2023.104031
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发表时间：
2023
影响因子：
4.8
通讯作者：
Sikora, Arthur
中科院分区：
文献类型：
--
作者：
Soni, Bhavya;Vemulapalli, Pritika;Lavin, Emily Schmitt;Sikora, Arthur
家族性高胆固醇血症（FH）是一种常染色体遗传性疾病，导致血液中低密度脂蛋白（LDL）水平升高。FH的主要原因之一是编码前蛋白转化酶枯草杆菌蛋白酶/kexin 9型（PCSK 9）的基因中的功能获得性突变。PCSK 9蛋白与肝细胞表面的LDL受体（LDLR）结合，并促进其降解，阻止LDLR的再循环，从而增加LDL血液水平。结合PCSK 9抑制LDLR结合的单克隆抗体疗法目前仅以注射剂形式提供。然而，几种口服生物可利用的PCSK 9抑制剂已经配制并正在进行临床试验。一种这样的疗法包含小分子肽抑制剂，其结合到位于催化结构域中的LDLR结合位点附近的隐蔽位点（N-末端沟）。螺旋区域（S153-I161）包含在该凹槽内，具有构象灵活性，使该区域对小分子肽开放。肽必须由两种组分组成：对PCSK 9具有高结合亲和力的螺旋肽和具有拮抗特性的附加延伸部分，以抑制LDLR结合。延伸必须侵入LDLR结合位点的疏水口袋，这显著有助于LDLR的结合能。使用在N端格罗夫中含有可去除肽（A（5VLP）和B（6 U3 I））的两种已知的PD B结构，创建三维打印模型以证明与疏水口袋的相互作用和接近。该模型突出了肽和PCSK 9上的关键氨基酸，以强调相互作用如何支持某些取代。PCSK 9残基Ile 369、Phe 379、Asp 238和Ala 239与肽B的有机部分（1-氨基-苯基环己烷-1-羰基）之间存在一种显著的相互作用。这些PCSK 9残基围绕LDLR结合区的疏水口袋，表明成功抑制。另一方面，添加到Trp 1锚上的肽A的FPG基序形成了一个β转角，该转角无法到达PCSK 9残基Ile 369、Phe 379、Asp 238和Ala 239，因此无法与之相互作用。通过3D模型，可以看到肽A具有β-转角，这阻止了进一步延伸到靶位点，限制了其拮抗能力。该模型还强调了肽B附着的有机部分，该部分到达近端LDLR结合区的疏水口袋，如文献所示，可以将结合亲和力增加> 100倍，同时降低总质量，以改善口服治疗。
Familial hypercholesterolemia (FH) is an autosomal genetic disease that causes elevated blood levels of low-density lipoprotein (LDL). One of the leading causes of FH is gain-of-function mutations in the gene coding for proprotein convertase subtilisin/kexin type 9 (PCSK9). The PCSK9 protein binds to LDL receptors (LDLR) on the surface of hepatocytes and promotes their degradation, preventing the recycling of LDLRs and thus increasing LDL blood levels. Monoclonal antibody therapies that bind to PCSK9 inhibiting LDLR binding are currently only available as an injection. However, several orally bioavailable PCSK9 inhibitors have been formulated and are undergoing clinical trials. One such therapy contains small-molecule-peptide inhibitors that bind to a cryptic site (N-terminal groove) adjacent to the LDLR binding site located in the catalytic domain. A helical region (S153-I161) is contained within this groove with conformational flexibility leaving the area open to small-molecule peptides. The peptide must consist of two components: a helical peptide with a high binding affinity to PCSK9 and an appended extension with antagonistic properties to inhibit LDLR binding. The extension must encroach upon the LDLR binding site’s hydrophobic pocket which significantly contributes to the binding energy of LDLR. Using two known PDB structures containing the removable peptides (A (5VLP) and B (6U3I)) in the N terminal grove, a three-dimensional printed model was created to demonstrate the interactions and proximity to the hydrophobic pocket. This model highlights critical amino acids on the peptides and PCSK9 to emphasize how the interactions support certain substitutions. One significant interaction lies between PCSK9 residues Ile369, Phe379, Asp238, and Ala239 and Peptide B’s organic moiety (1-amino-phenylcyclohexane-1-carbonyl). These PCSK9 residues surround the LDLR binding region's hydrophobic pocket indicating a successful inhibition. On the other hand, Peptide A’s FPG motif added to the Trp1 anchor formed a beta-turn which was unable to reach and, therefore, interact with PCSK9 residues Ile369, Phe379, Asp238, and Ala239. Through the 3D model, it was visualized that Peptide A had a beta-turn that precluded further extension into the target site, limiting its antagonistic ability. The model also highlighted Peptide B’s attached organic moiety which reaches the hydrophobic pocket in the proximal LDLR binding region, as shown in the literature to increase the binding affinity by> 100 fold with reduced overall mass for an improved oral therapeutic.