Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Colchester, VT 05446, USA.
National Magnetic Resonance Facility at Madison and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
J Mol Biol. 2014 Apr 17;426(8):1661-76. doi: 10.1016/j.jmb.2013.12.007. Epub 2013 Dec 12.
The monocytic leukemic zinc finger (MOZ) histone acetyltransferase (HAT) acetylates free histones H3, H4, H2A, and H2B in vitro and is associated with up-regulation of gene transcription. The MOZ HAT functions as a quaternary complex with the bromodomain-PHD finger protein 1 (BRPF1), inhibitor of growth 5 (ING5), and hEaf6 subunits. BRPF1 links the MOZ catalytic subunit to the ING5 and hEaf6 subunits, thereby promoting MOZ HAT activity. Human BRPF1 contains multiple effector domains with known roles in gene transcription, as well as chromatin binding and remodeling. However, the biological function of the BRPF1 bromodomain remains unknown. Our findings reveal novel interactions of the BRPF1 bromodomain with multiple acetyllysine residues on the N-terminus of histones and show that it preferentially selects for H2AK5ac, H4K12ac, and H3K14ac. We used chemical shift perturbation data from NMR titration experiments to map the BRPF1 bromodomain ligand binding pocket and identified key residues responsible for coordination of the post-translationally modified histones. Extensive molecular dynamics simulations were used to generate structural models of bromodomain-histone ligand complexes, to analyze hydrogen bonding and other interactions, and to calculate the binding free energies. Our results outline the molecular mechanism driving binding specificity of the BRPF1 bromodomain for discrete acetyllysine residues on the N-terminal histone tails. Together, these data provide insights into how histone recognition by the bromodomain directs the biological function of BRPF1, ultimately targeting the MOZ HAT complex to chromatin substrates.
单核细胞白血病锌指（MOZ）组蛋白乙酰转移酶（HAT）在体外乙酰化游离组蛋白 H3、H4、H2A 和 H2B，并与基因转录的上调有关。MOZ HAT 作为一个四元复合物与溴结构域-PHD 指蛋白 1（BRPF1）、生长抑制剂 5（ING5）和 hEaf6 亚基相关。BRPF1 将 MOZ 催化亚基与 ING5 和 hEaf6 亚基连接起来，从而促进 MOZ HAT 活性。人 BRPF1 包含多个效应结构域，已知在基因转录以及染色质结合和重塑中具有作用。然而，BRPF1 溴结构域的生物学功能仍然未知。我们的发现揭示了 BRPF1 溴结构域与组蛋白 N 端多个乙酰赖氨酸残基的新相互作用，并表明它优先选择 H2AK5ac、H4K12ac 和 H3K14ac。我们使用 NMR 滴定实验的化学位移扰动数据来绘制 BRPF1 溴结构域配体结合口袋，并确定了负责协调翻译后修饰组蛋白的关键残基。广泛的分子动力学模拟用于生成溴结构域-组蛋白配体复合物的结构模型，分析氢键和其他相互作用，并计算结合自由能。我们的结果概述了 BRPF1 溴结构域对组蛋白 N 端尾部离散乙酰赖氨酸残基结合特异性的分子机制。这些数据共同提供了关于溴结构域识别组蛋白如何指导 BRPF1 生物学功能的见解，最终将 MOZ HAT 复合物靶向染色质底物。
