Summary Ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) exhibits catalytic promiscuity, resulting in error‐prone reactions and the formation of inhibitory sugar phosphates. Specifically, Xylulose‐1,5‐bisphosphate (XuBP) acts as an inhibitor by binding to the active site of Rubisco, thereby impairing its catalytic function. Thermolabile Rubisco activase (Rca) facilitates the release of such inhibitors, including XuBP, by remodelling Rubisco. In Arabidopsis thaliana, the phosphatase pair CbbYA and CbbYB subsequently hydrolyses XuBP to prevent its rebinding to Rubisco. To explore the functional interplay between these components in maintaining photosynthesis, cbbya, cbbyb and cbbyab mutants were crossed with RCA knockdown (rca‐2) lines. Additionally, both RCA and CBBYA were overexpressed in wild‐type (WT) Arabidopsis thaliana. Phenotypic analyses revealed an exacerbation in decreased growth and photosynthetic efficiency in the cbbyab rca‐2 double mutants compared with the control mutants (cbbyab and rca‐2), indicating a negative genetic interaction. Furthermore, the co‐overexpression of RCA and CBBYA did not improve photosynthesis under short‐term heat stress, and light reactions were adversely affected relative to the WT. These findings illustrate the synergistic roles of Rca, CbbYA and CbbYB in maintaining carbon fixation and promoting plant growth in Arabidopsis thaliana. Thus, the coordinated regulation of Rca and CbbY enzymes is crucial for optimizing photosynthetic efficiency.

中文翻译：

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Rubisco 抑制剂释放和降解在光合作用中的协同作用


摘要 核酮糖-1,5-二磷酸羧化酶/加氧酶 （Rubisco） 表现出催化混杂性，导致容易出错的反应和抑制性糖磷酸盐的形成。具体来说，木酮糖-1,5-二磷酸 （XuBP） 通过与 Rubisco 的活性位点结合而起抑制剂的作用，从而损害其催化功能。不耐热的 Rubisco 激活酶 （Rca） 通过重塑 Rubisco 促进此类抑制剂的释放，包括 XuBP。在拟南芥中，磷酸酶对 CbbYA 和 CbbYB 随后水解 XuBP 以防止其与 Rubisco 重新结合。为了探索这些成分在维持光合作用中的功能相互作用，将 cbbya、cbbyb 和 cbbyab 突变体与 RCA 敲除 （rca-2） 系杂交。此外，RCA 和 CBBYA 在野生型 （WT） 拟南芥中过表达。表型分析显示，与对照突变体 （cbbyab 和 rca-2） 相比，cbbyab rca-2 双突变体的生长和光合效率下降加剧，表明负遗传相互作用。此外，RCA 和 CBBYA 的共过表达在短期热应激下并未改善光合作用，并且相对于 WT 受到不利影响。这些发现说明了 Rca、CbbYA 和 CbbYB 在拟南芥维持碳固定和促进植物生长中的协同作用。因此，Rca 和 CbbY 酶的协调调节对于优化光合效率至关重要。