Kim Minjae, Kim Ji Yeon, Han Kyong Ha, Shin Hyeon Ho, Jin EonSeon
Library of Marine Samples, Korea Institute of Ocean Science & Technology, Geoje, 53201, Republic of Korea.
Department of Environmental Sciences, Hanyang University, Seoul, 222 04763, Republic of Korea.
Microb Cell Fact. 2025 Aug 22;24(1):194. doi: 10.1186/s12934-025-02824-8.
Microalgae are promising sustainable feedstocks for biodiesel production. Among the primary carbon reservoirs in microalgae, starch and lipids are the main targets for metabolic engineering aimed at enhancing productivity. Redirecting carbon flux from starch toward lipid biosynthesis has been considered an effective strategy to improve lipid yield, and manipulating upstream regulators may allow broader control over metabolic networks. DYRKP1, a plant-specific dual-specificity tyrosine-phosphorylation-regulated kinase conserved in photosynthetic eukaryotes, has been implicated in regulating intracellular carbon partitioning. In this study, we investigated the physiological and metabolic effects of DYRKP1 deficiency in a cell-wall-less strain of Chlamydomonas reinhardtii. To further enhance lipid accumulation, we additionally knocked out ADP-glucose pyrophosphorylase (AGP), a key enzyme involved in starch biosynthesis. The total fatty acid content of DYRKP1-AGP double knockout (dKO) mutants was higher than that of their parental strain (CC4349) under both nitrogen-replete and deplete conditions, and was even 1.2-fold higher than that of the AGP single knockout (agp) mutant under nitrogen-deplete conditions. The DYRKP1 single knockout mutants exhibited fatty acid composition similar to the parental strain, regardless of nitrogen depletion. The fatty acid composition of the dKO mutants resembled that of the agp mutant under nitrogen-replete conditions, but diverged upon nitrogen starvation, suggesting a conditional interaction between upstream regulation and metabolic flux. This finding implies that disrupting upstream regulators like DYRKP1 may offer limited additional benefit when key downstream bottlenecks, such as starch biosynthesis, are already removed. Overall, our study underscores the layered complexity of carbon partitioning in C. reinhardtii and the importance of context-dependent metabolic regulation in optimizing lipid production.
微藻是用于生物柴油生产的有前景的可持续原料。在微藻的主要碳库中，淀粉和脂质是旨在提高生产力的代谢工程的主要目标。将碳通量从淀粉转向脂质生物合成被认为是提高脂质产量的有效策略，而操纵上游调节因子可能允许对代谢网络进行更广泛的控制。DYRKP1是一种在光合真核生物中保守的植物特异性双特异性酪氨酸磷酸化调节激酶，已被证明参与调节细胞内碳分配。在本研究中，我们研究了莱茵衣藻无细胞壁菌株中DYRKP1缺陷的生理和代谢影响。为了进一步提高脂质积累，我们还敲除了淀粉生物合成中的关键酶ADP-葡萄糖焦磷酸化酶（AGP）。在氮充足和缺乏条件下，DYRKP1-AGP双敲除（dKO）突变体的总脂肪酸含量均高于其亲本菌株（CC4349），在氮缺乏条件下甚至比AGP单敲除（agp）突变体高1.2倍。无论氮是否缺乏，DYRKP1单敲除突变体的脂肪酸组成与亲本菌株相似。在氮充足条件下，dKO突变体的脂肪酸组成与agp突变体相似，但在氮饥饿时发生分歧，这表明上游调节和代谢通量之间存在条件性相互作用。这一发现意味着，当关键的下游瓶颈（如淀粉生物合成）已经消除时，破坏像DYRKP1这样的上游调节因子可能只会带来有限的额外益处。总体而言，我们的研究强调了莱茵衣藻中碳分配的层次复杂性以及上下文依赖性代谢调节在优化脂质生产中的重要性。
