MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, United States.
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, United States; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, United States.
Metab Eng. 2024 Jan;81:38-52. doi: 10.1016/j.ymben.2023.11.001. Epub 2023 Nov 2.
Photosynthetic organisms need to balance the rate of photosynthesis with the utilization of photosynthetic products by downstream reactions. While such "source/sink" pathways are well-interrogated in plants, analogous regulatory systems are unknown or poorly studied in single-celled algal and cyanobacterial species. Towards the identification of energy/sugar sensors in cyanobacteria, we utilized an engineered strain of Synechococcus elongatus PCC 7942 that allows experimental manipulation of carbon status. We conducted a screening of all two-component systems (TCS) and serine/threonine kinases (STKs) encoded in S. elongatus PCC 7942 by analyzing phenotypes consistent with sucrose-induced relaxation of sink inhibition. We narrowed the candidate sensor proteins by analyzing changes observed after sucrose feeding. We show that a clustered TCS network containing RpaA, CikB, ManS and NblS are involved in the regulation of genes related to photosynthesis, pigment synthesis, and Rubisco concentration in response to sucrose. Altogether, these results highlight a regulatory TCS group that may play under-appreciated functions in carbon partitioning and energy balancing in cyanobacteria.
光合生物需要将光合作用的速度与下游反应对光合作用产物的利用速度相平衡。虽然在植物中已经很好地研究了这种“源/汇”途径，但在单细胞藻类和蓝细菌物种中，类似的调控系统尚不清楚或研究甚少。为了鉴定蓝细菌中的能量/糖传感器，我们利用了一种经过工程改造的 Synechococcus elongatus PCC 7942 菌株，该菌株允许对碳状态进行实验操作。我们通过分析与蔗糖诱导的汇抑制松弛一致的表型，对 Synechococcus elongatus PCC 7942 中编码的所有双组分系统（TCS）和丝氨酸/苏氨酸激酶（STK）进行了筛选。我们通过分析蔗糖喂养后观察到的变化，缩小了候选传感器蛋白的范围。我们表明，包含 RpaA、CikB、ManS 和 NblS 的簇集 TCS 网络参与了与蔗糖响应相关的光合作用、色素合成和 Rubisco 浓度相关基因的调节。总之，这些结果突出了一个调控 TCS 群体，它可能在蓝细菌的碳分配和能量平衡中发挥着被低估的作用。
