Low complexity regions are involved in the assembly and disassembly of P-bodies (PBs). Saccharomyces cerevisiae contains three genes encoding the protein kinase A (PKA) catalytic subunit: TPK1, TPK2 and TPK3. Tpk2 and Tpk3 isoforms localize to PBs upon glucose starvation showing different mechanisms and kinetics of accumulation. In contrast to the other two isoforms, Tpk2 harbors a glutamine-rich prion-like domain (PrLD) at the N-terminus. Here we show that the appearance of Tpk2 foci in response to glucose starvation, heat stress or stationary phase was dependent on its PrLD. Moreover, the PrLD of Tpk2 was necessary for efficient PB and stress granule aggregation during stress conditions and in quiescent cells. Deletion of PrLD does not affect the in vitro and in vivo kinase activity of Tpk2 or its interaction with the regulatory subunit Bcy1. We present evidence that the PrLD of Tpk2 serves as a scaffold domain for PB assembly in a manner that is independent of Pat1 phosphorylation by PKA. In addition, a mutant strain where Tpk2 lacks PrLD showed a decrease of turnover of mRNA during glucose starvation. This work therefore provides new insight into the mechanism of stress-induced cytoplasmic mRNP assembly, and the role of isoform specific domains in the regulation of PKA catalytic subunit specificity and dynamic localization to cytoplasmic RNPs granules.

P 体 (PB) 的组装和拆卸涉及低复杂性区域。酿酒酵母含有三个编码蛋白激酶 A (PKA) 催化亚基的基因：TPK1、TPK2和TPK3. Tpk2 和 Tpk3 亚型在葡萄糖饥饿时定位于 PB，显示出不同的积累机制和动力学。与其他两种同种型相比，Tpk2 在 N 末端具有富含谷氨酰胺的朊病毒样结构域 (PrLD)。在这里，我们表明 Tpk2 病灶响应葡萄糖饥饿、热应激或稳定期的出现取决于其 PrLD。此外，Tpk2 的 PrLD 对于在应激条件下和静止细胞中有效的 PB 和应激颗粒聚集是必需的。PrLD 的删除不影响体外和体内Tpk2 的激酶活性或其与调节亚基 Bcy1 的相互作用。我们提供证据表明 Tpk2 的 PrLD 以独立于 PKA 的 Pat1 磷酸化的方式作为 PB 组装的支架结构域。此外，Tpk2 缺乏 PrLD 的突变株显示葡萄糖饥饿期间 mRNA 的转换减少。因此，这项工作提供了对应激诱导细胞质 mRNP 组装机制的新见解，以及亚型特定结构域在调节 PKA 催化亚基特异性和细胞质 RNP 颗粒动态定位中的作用。