The AT-rich interaction domain (ARID) containing BAF250a is a subunit of the BAF-A class of SWI/SNF chromatin remodeling complexes. The ARID belongs to a family of conserved DNA binding domains found in several eukaryotic proteins; however, its exact contribution to BAF250a function and the mechanism of its DNA binding are not well understood. Here we have probed the interaction of the BAF250a ARID with three different double-stranded DNA (dsDNA) sequences to understand its DNA binding properties. A comprehensive biophysical and thermodynamic study using nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry revealed the complex nature of BAF250a ARID-DNA interactions. The thermodynamic signatures of the BAF250a ARID with 12 A-T bp dsDNA (AT-12) are distinct from those of 12 G-C bp dsDNA (GC-12) or 12 bp Dickerson dodecamer DNA (DD-12) sequences. We observed that the binding of the BAF250a ARID with AT-12 DNA is enthalpically driven in a tested temperature range of 5-25 °C. BAF250a ARID/AT-12 DNA interaction exhibited a larger negative calorimetric specific heat change (ΔCp) compared to that of BAF250a ARID/GC-12 DNA or BAF250a ARID/DD-12 DNA interactions. In the presence of salt (NaCl), ARID/AT-12 DNA binding was less perturbed than ARID/GC-12 DNA or ARID/DD-12 DNA binding. Overall, these results show that BAF250a ARID/AT-12 DNA interaction has signatures of "specific" binding. Furthermore, using NMR chemical shift perturbation experiments, we have identified DNA binding residues on the BAF250a ARID and generated a data-driven HADDOCK model of the ARID/DNA complex that was further supported by mutating key lysine residues that were found to be important for DNA binding.

中文翻译：

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BAF250a富AT相互作用域的特定DNA结合的签名。

含有BAF250a的富含AT的相互作用域（ARID）是SWI / SNF染色质重塑复合物的BAF-A类的亚基。ARID属于在几个真核蛋白中发现的保守的DNA结合域家族。然而，它对BAF250a功能的确切贡献及其与DNA结合的机制尚不十分清楚。在这里，我们已经探究了BAF250a ARID与三种不同的双链DNA（dsDNA）序列的相互作用，以了解其DNA结合特性。使用核磁共振（NMR）光谱和等温滴定量热法进行的全面生物物理和热力学研究揭示了BAF250a ARID-DNA相互作用的复杂性。具有12个AT bp dsDNA（AT-12）的BAF250a ARID的热力学特征不同于12个GC bp dsDNA（GC-12）或12 bp Dickerson dodecamer DNA（DD-12）序列的热力学特征。我们观察到，BAF250a ARID与AT-12 DNA的结合在5-25°C的测试温度范围内受到焓驱动。与BAF250a ARID / GC-12 DNA或BAF250a ARID / DD-12 DNA相互作用相比，BAF250a ARID / AT-12 DNA相互作用显示出更大的负量热比变化（ΔCp）。在盐（NaCl）存在的情况下，ARID / AT-12 DNA的结合比ARID / GC-12 DNA或ARID / DD-12 DNA的结合受干扰小。总的来说，这些结果表明BAF250a ARID / AT-12 DNA相互作用具有“特异性”结合的特征。此外，使用NMR化学位移扰动实验，