University of Michigan, Life Sciences Institute, 210 Washentaw Avenue, Ann Arbor, MI, 48109, USA.
Chembiochem. 2018 Sep 17;19(18):1907-1912. doi: 10.1002/cbic.201800173. Epub 2018 Sep 5.
The GACKIX activator binding domain has been a compelling target for small-molecule probe discovery because of the central role of activator-GACKIX complexes in diseases ranging from leukemia to memory disorders. Additionally, GACKIX is an ideal model to dissect the context-dependent function of activator-coactivator complexes. However, the dynamic and transient protein-protein interactions (PPIs) formed by GACKIX are difficult targets for small molecules. An additional complication is that activator-binding motifs, such as GACKIX, are found in multiple coactivators, making specificity difficult to attain. In this study, we demonstrate that the strategy of tethering can be used to rapidly discover highly specific covalent modulators of the dynamic PPIs between activators and coactivators. These serve as both ortho- and allosteric modulators, enabling the tunable assembly or disassembly of the activator-coactivator complexes formed between the KIX domain and its cognate activator binding partners MLL and CREB. The molecules maintain their function and selectivity, even in human cell lysates and in bacterial cells, and thus, will ultimately be highly useful probes for cellular studies.
GACKIX 激活剂结合结构域一直是小分子探针发现的一个引人注目的目标，因为激活剂-GACKIX 复合物在从白血病到记忆障碍等疾病中的核心作用。此外，GACKIX 是一个理想的模型，可以剖析激活剂共激活剂复合物的上下文相关功能。然而，GACKIX 形成的动态和瞬时蛋白质-蛋白质相互作用（PPIs）是小分子的难标靶。一个额外的复杂情况是，激活剂结合基序，如 GACKIX，存在于多个共激活剂中，使得特异性难以实现。在这项研究中，我们证明了连接的策略可以用于快速发现激活剂和共激活剂之间动态 PPIs 的高度特异性共价调节剂。这些调节剂既作为正调节剂又作为变构调节剂，能够调节 KIX 结构域与其同源激活剂结合伙伴 MLL 和 CREB 之间形成的激活剂-共激活剂复合物的组装或拆卸。这些分子即使在人细胞裂解物和细菌细胞中也能保持其功能和选择性，因此，它们最终将成为细胞研究的非常有用的探针。
