Pattelli Olivia N, Valdivia Estefanía Martínez, Beyersdorf Matthew S, Regan Clint S, Rivas Mónica, Merajver Sofia D, Cierpicki Tomasz, Mapp Anna K
bioRxiv. 2023 Mar 25:2023.03.24.534168. doi: 10.1101/2023.03.24.534168.
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 (34913-8) increases the affinity for the coactivator Med25 >10-fold ( >>100 μM to 10 μM). Importantly, the selectivity of 34913-8 for Med25 compared to other coactivators is excellent. 34913-8 engages Med25 through interaction with the H2 face of its Ac tivator I nteraction D omain 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, 34913-8 is a useful tool for studying Med25 and the Mediator complex biology and the results indicate that lipopeptidomimetics may be a robust source of inhibitors for activator-coactivator complexes.
短的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结构域相同的结合表面。然而，它们的结合亲和力适中，选择性普遍较差，这限制了它们作为合成调节剂的用途。在这里，我们表明，在一种这样的七聚体脂肽模拟物（34913-8）的N端引入中链支链脂肪酸，可使对共激活因子Med25的亲和力增加10倍以上（从>>100 μM提高到10 μM）。重要的是，与其他共激活因子相比，34913-8对Med25的选择性极佳。34913-8通过与其激活因子相互作用结构域的H2面相互作用来结合Med25，这样做可使细胞蛋白质组中的全长蛋白稳定。此外，在三阴性乳腺癌细胞模型中，受Med25-激活因子蛋白-蛋白相互作用调控的基因受到抑制。因此，34913-8是研究Med25和中介体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因子-共激活因子复合物抑制剂的丰富来源。
