School of Molecular Sciences, The University of Western Australia, Crawley, WA 6009, Australia.
Department of Core Antisense Research, IONIS Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Nucleic Acids Res. 2022 Jan 11;50(1):522-535. doi: 10.1093/nar/gkab1216.
The Drosophila behaviour/human splicing (DBHS) proteins are a family of RNA/DNA binding cofactors liable for a range of cellular processes. DBHS proteins include the non-POU domain-containing octamer-binding protein (NONO) and paraspeckle protein component 1 (PSPC1), proteins capable of forming combinatorial dimers. Here, we describe the crystal structures of the human NONO and PSPC1 homodimers, representing uncharacterized DBHS dimerization states. The structures reveal a set of conserved contacts and structural plasticity within the dimerization interface that provide a rationale for dimer selectivity between DBHS paralogues. In addition, solution X-ray scattering and accompanying biochemical experiments describe a mechanism of cooperative RNA recognition by the NONO homodimer. Nucleic acid binding is reliant on RRM1, and appears to be affected by the orientation of RRM1, influenced by a newly identified 'β-clasp' structure. Our structures shed light on the molecular determinants for DBHS homo- and heterodimerization and provide a basis for understanding how DBHS proteins cooperatively recognize a broad spectrum of RNA targets.
果蝇行为/人类剪接 (DBHS) 蛋白是一组 RNA/DNA 结合辅助因子，参与多种细胞过程。DBHS 蛋白包括非 POU 结构域包含的八聚体结合蛋白 (NONO) 和核周体蛋白成分 1 (PSPC1)，它们能够形成组合二聚体。在这里，我们描述了人类 NONO 和 PSPC1 同源二聚体的晶体结构，代表了未表征的 DBHS 二聚化状态。这些结构揭示了二聚化界面内的一组保守接触和结构可塑性，为 DBHS 同源物之间的二聚体选择性提供了依据。此外，溶液 X 射线散射和伴随的生化实验描述了 NONO 同源二聚体协同识别 RNA 的机制。核酸结合依赖于 RRM1，并且似乎受到 RRM1 取向的影响，受新鉴定的“β 夹”结构的影响。我们的结构阐明了 DBHS 同型和异型二聚体形成的分子决定因素，并为理解 DBHS 蛋白如何协同识别广泛的 RNA 靶标提供了基础。
