Biomolecular condensation is a way of organizing cytosol in which proteins and nucleic acids coassemble into compartments. In the multinucleate filamentous fungus Ashbya gossypii, the RNA-binding protein Whi3 regulates the cell cycle and cell polarity through forming macromolecular structures that behave like condensates. Whi3 has distinct spatial localizations and mRNA targets, making it a powerful model for how, when, and where specific identities are established for condensates. We identified residues on Whi3 that are differentially phosphorylated under specific conditions and generated mutants that ablate this regulation. This yielded separation of function alleles that were functional for either cell polarity or nuclear cycling but not both. This study shows that phosphorylation of individual residues on molecules in biomolecular condensates can provide specificity that gives rise to distinct functional identities in the same cell.

中文翻译：

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磷酸调节为细胞周期和细胞极性中的生物分子凝聚体提供特异性

生物分子缩合是组织细胞质的一种方式，其中蛋白质和核酸共同组装成区室。在多核丝状真菌 Ashbya gossypii 中，RNA 结合蛋白 Whi3 通过形成类似凝聚物的大分子结构来调节细胞周期和细胞极性。Whi3 具有独特的空间定位和 mRNA 靶标，使其成为如何、何时、何地为凝结物建立特定身份的强大模型。我们鉴定了 Whi3 上在特定条件下差异磷酸化的残基，并产生了消除这种调节的突变体。这产生了功能等位基因的分离，这些等位基因对细胞极性或核循环有功能，但不能同时对两者都有功能。这项研究表明，生物分子凝聚物中分子上各个残基的磷酸化可以提供特异性，从而在同一细胞中产生不同的功能特性。