Sorbonne Université, CNRS, UMR 7238, Institut de Biologie Paris-Seine, Laboratoire de Biologie Computationnelle et Quantitative, 4 place Jussieu, F-75005 Paris, France; Sorbonne Université, CNRS, UMR 8226, Institut de Biologie Physico-Chimique, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, 13 rue Pierre et Marie Curie, 75005 Paris, France; Faculty of Sciences, Doctoral School of Plant Sciences, Université Paris-Saclay, 91190 Saint-Aubin, France.
Sorbonne Université, CNRS, UMR 7238, Institut de Biologie Paris-Seine, Laboratoire de Biologie Computationnelle et Quantitative, 4 place Jussieu, F-75005 Paris, France.
J Struct Biol. 2022 Sep;214(3):107873. doi: 10.1016/j.jsb.2022.107873. Epub 2022 Jun 6.
The Calvin-Benson cycle fixes carbon dioxide into organic triosephosphates through the collective action of eleven conserved enzymes. Regeneration of ribulose-1,5-bisphosphate, the substrate of Rubisco-mediated carboxylation, requires two lyase reactions catalyzed by fructose-1,6-bisphosphate aldolase (FBA). While cytoplasmic FBA has been extensively studied in non-photosynthetic organisms, functional and structural details are limited for chloroplast FBA encoded by oxygenic phototrophs. Here we determined the crystal structure of plastidial FBA from the unicellular green alga Chlamydomonas reinhardtii (Cr). We confirm that CrFBA folds as a TIM barrel, describe its catalytic pocket and homo-tetrameric state. Multiple sequence profiling classified the photosynthetic paralogs of FBA in a distinct group from non-photosynthetic paralogs. We mapped the sites of thiol- and phospho-based post-translational modifications known from photosynthetic organisms and predict their effects on enzyme catalysis.
卡尔文-本森循环通过十一种保守酶的集体作用将二氧化碳固定为有机三磷酸丙糖。核酮糖 1,5-二磷酸（Rubisco 介导羧化作用的底物）的再生需要果糖-1,6-二磷酸醛缩酶（FBA）催化的两个裂解反应。虽然细胞质 FBA 在非光合生物中得到了广泛研究，但编码产氧光合生物的叶绿体 FBA 的功能和结构细节有限。在这里，我们确定了单细胞绿藻莱茵衣藻（Chlamydomonas reinhardtii）（Cr）的质体 FBA 的晶体结构。我们证实 CrFBA 折叠为 TIM 桶，描述了其催化口袋和同四聚体状态。多序列分析将 FBA 的光合作用同源物分类为与非光合作用同源物不同的特定组。我们绘制了已知存在于光合生物中的基于巯基和磷酸的翻译后修饰的位点，并预测了它们对酶催化的影响。
