Compartmentation of enzymes via filamentation has arisen as a mechanism for the regulation of metabolism. In 2010, three groups independently reported that CTP synthase (CTPS) can assemble into a filamentous structure termed the cytoophidium. In searching for CTPS-interacting proteins, here we perform a yeast two-hybrid screening of Drosophila proteins and identify a putative CTPS-interacting protein, △¹-pyrroline-5-carboxylate synthase (P5CS). Using the Drosophila follicle cell as the in vivo model, we confirm that P5CS forms cytoophidia, which are associated with CTPS cytoophidia. Overexpression of P5CS increases the length of CTPS cytoophidia. Conversely, filamentation of CTPS affects the morphology of P5CS cytoophidia. Finally, in vitro analyses confirm the filament-forming property of P5CS. Our work links CTPS with P5CS, two enzymes involved in the rate-limiting steps in pyrimidine and proline biosynthesis, respectively.

通过细丝化作用形成的酶区室已经成为调节代谢的机制。在2010年，三个小组独立报告了CTP合酶（CTPS）可以组装成丝状结构，称为细胞膜。在寻找与CTPS相互作用的蛋白时，我们对果蝇蛋白进行了酵母双杂交筛选，并确定了一个与CTPS相互作用的假定蛋白△ ^1-吡咯啉-5-羧酸合酶（P5CS）。使用果蝇卵泡细胞作为体内模型，我们确认P5CS形成了细胞吞噬症，这与CTPS细胞吞噬症相关。P5CS的过表达增加了CTPS胞吞的长度。相反，CTPS的丝化会影响P5CS胞吞的形态。最后，体外分析证实了P5CS的长丝形成特性。我们的工作将CTPS与P5CS联系起来，P5CS是参与嘧啶和脯氨酸生物合成的限速步骤的两种酶。