Dipartimento di Bioscienze, Università degli Studi di Milano, Milano 20133, Italy.
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Science, Moscow 119333, Russian Federation.
Int J Biol Macromol. 2021 Dec 15;193(Pt A):401-413. doi: 10.1016/j.ijbiomac.2021.10.056. Epub 2021 Oct 18.
The trimeric CCAAT-binding NF-Y is a "pioneer" Transcription Factor -TF- known to cooperate with neighboring TFs to regulate gene expression. Genome-wide analyses detected a precise stereo-alignment -10/12 bp- of CCAAT with E-box elements and corresponding colocalization of NF-Y with basic-Helix-Loop-Helix (bHLH) TFs. We dissected here NF-Y interactions with USF1 and MAX. USF1, but not MAX, cooperates in DNA binding with NF-Y. NF-Y and USF1 synergize to activate target promoters. Reconstruction of complexes by structural means shows independent DNA binding of MAX, whereas USF1 has extended contacts with NF-Y, involving the USR, a USF-specific amino acid sequence stretch required for trans-activation. The USR is an intrinsically disordered domain and adopts different conformations based on E-box-CCAAT distances. Deletion of the USR abolishes cooperative DNA binding with NF-Y. Our data indicate that the functionality of certain unstructured domains involves adapting to small variation in stereo-alignments of the multimeric TFs sites.
三聚体 CCAAT 结合 NF-Y 是一种“先驱”转录因子-TF-，已知与邻近的 TF 合作调节基因表达。全基因组分析检测到 CCAAT 与 E 盒元件的精确立体对准-10/12 bp-，以及 NF-Y 与碱性螺旋-环-螺旋（bHLH）TF 的相应共定位。我们在这里解析了 NF-Y 与 USF1 和 MAX 的相互作用。USF1 但不是 MAX 与 NF-Y 协同进行 DNA 结合。NF-Y 和 USF1 协同激活靶启动子。通过结构手段重建复合物表明 MAX 具有独立的 DNA 结合，而 USF1 与 NF-Y 有扩展的接触，涉及 USR，这是一个 USF 特异性的氨基酸序列延伸，需要进行反式激活。USR 是一个固有无序的结构域，根据 E 盒-CCAAT 距离采用不同的构象。删除 USR 会使 NF-Y 的协同 DNA 结合能力丧失。我们的数据表明，某些无结构域的功能涉及适应多聚体 TF 结合位点的立体对准的微小变化。
