PDF(Pubmed)
Abstract：
Short amphipathic peptides are capable of binding to transcriptional coactivators, often targeting the same binding surfaces as native transcriptional activation domains. However, they do so with modest affinity and generally poor selectivity, limiting their utility as synthetic modulators. Here we show that incorporation of a medium-chain, branched fatty acid to the N-terminus of one such heptameric lipopeptidomimetic (LPPM-8) increases the affinity for the coactivator Med25 >20-fold (Ki >100 μM to 4 μM), rendering it an effective inhibitor of Med25 protein-protein interactions (PPIs). The lipid structure, the peptide sequence, and the C-terminal functionalization of the lipopeptidomimetic each influence the structural propensity of LPPM-8 and its effectiveness as an inhibitor. LPPM-8 engages Med25 through interaction with the H2 face of its activator interaction domain and in doing so stabilizes full-length protein in the cellular proteome. Further, genes regulated by Med25-activator PPIs are inhibited in a cell model of triple-negative breast cancer. Thus, LPPM-8 is a useful tool for studying Med25 and mediator complex biology and the results indicate that lipopeptidomimetics may be a robust source of inhibitors for activator-coactivator complexes.
摘要：
短两亲性肽能够与转录共激活因子结合，通常靶向与天然转录激活域相同的结合表面。然而,它们的亲和力适中，选择性一般较差，限制了它们作为合成调节剂的用途。在这里，我们展示了一个中链的合并，一个这样的七聚体脂肽模拟物（LPPM-8）的N末端的支链脂肪酸增加了对共激活剂Med25的亲和力>20倍（Ki>100μM至4μM），使其成为Med25蛋白质-蛋白质相互作用（PPI）的有效抑制剂。脂质结构，肽序列，和脂肽模拟物的C端官能化各自影响LPPM-8的结构倾向及其作为抑制剂的有效性。LPPM-8通过与其激活因子相互作用域的H2面相互作用而与Med25结合，并且这样做可以稳定细胞蛋白质组中的全长蛋白质。Further,在三阴性乳腺癌细胞模型中，由Med25激活剂PPIs调控的基因受到抑制。因此，LPPM-8是研究Med25和Mediator复合物生物学的有用工具，结果表明脂肽模拟物可能是激活剂-共激活剂复合物抑制剂的强大来源。
