NARROW LEAF 1 ( NAL1 ), originally identified for its role in shaping leaf morphology, plant architecture, and various agronomic traits in rice, has remained enigmatic in terms of the molecular mechanisms governing its multifaceted functions. In this study, we present a comprehensive structural analysis of NAL1 proteins, shedding light on how NAL1 regulates the phase separation of its physiological substrate, FRIZZY PANICLE (FZP), a transcription factor. We determined that NAL1 assembles as a hexamer and forms a molecular cage with a wide central channel and three narrower lateral channels, which could discriminate its different substrates into the catalytic sites. Most notably, our investigation unveils that FZP readily forms molecular condensates via phase separation both in vitro and in vivo. NAL1 fine-tunes FZP condensation, maintaining optimal concentrations to enhance transcriptional activity. While phase separation roles include sequestration and suppression of transcriptional or enzymatic activity, our study highlights its context-dependent contribution to transcriptional regulation. NAL1 assumes a pivotal role in regulating the states of these molecular condensates through its proteolytic activity, subsequently enhancing transcriptional cascades. Our findings offer insights into comprehending the molecular mechanisms underpinning NAL1’s diverse functions, with far-reaching implications for the field of plant biology. Additionally, these insights provide valuable guidance for the development of rational breeding strategies aimed at enhancing crop productivity.

中文翻译：

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NAL1 形成分子笼以调节 FZP 相分离


窄叶 1 （ NAL1 ） 最初因其在塑造水稻叶片形态、植物结构和各种农艺性状中的作用而被确定，但在控制其多方面功能的分子机制方面仍然是个谜。在这项研究中，我们提出了 NAL1 蛋白的全面结构分析，阐明了 NAL1 如何调节其生理底物卷曲圆锥花序 （FZP）（一种转录因子）的相分离。我们确定 NAL1 组装为六聚体并形成一个分子笼，具有一个宽的中央通道和三个较窄的侧通道，可以将其不同的底物区分到催化位点。最值得注意的是，我们的研究揭示了 FZP 在体外和体内都很容易通过相分离形成分子缩合物。NAL1 微调 FZP 缩合，保持最佳浓度以增强转录活性。虽然相分离作用包括转录或酶活性的隔离和抑制，但我们的研究强调了其对转录调控的上下文依赖性贡献。NAL1 通过其蛋白水解活性在调节这些分子凝聚物的状态中起关键作用，随后增强转录级联反应。我们的研究结果为理解支撑 NAL1 不同功能的分子机制提供了见解，对植物生物学领域具有深远的影响。此外，这些见解为制定旨在提高作物生产力的合理育种策略提供了有价值的指导。