Geranylgeranyl diphosphate (GGPP, C20) is a key metabolic intermediate shared by several vital metabolic pathways, including the biosynthesis of carotenoids, the phytol side chains of chlorophylls and tocopherols, and diterpenoids such as gibberellins. In plants, the biosynthesis of GGPP is catalyzed by GGPP synthases (GGPPSs), some of which also produce geranyl diphosphate (C10) as their side-products. Despite of the key role of GGPP as an essential metabolic hub for plant growth, development and acclimation, there are limited studies on its supply by GGPPS in land plants and, even rarely, in algae. Here, we report the cloning and functional characterization of a GGPPS (BfGGPPS) from the intertidal red algal seaweed Bangia fuscopurpurea. Our in vivo and in vitro assays collectively demonstrated that BfGGPPS is a bona fide GGPPS that produces GGPP as its only product. By yeast two-hybrid assay, BfGGPPS revealed its interaction with a putative phytoene synthase, the entry enzyme for carotenoid biosynthesis, indicating a possible mechanism modulating metabolic flux through protein-protein interaction in red algae. Our phylogenetic analysis suggests an early divergence of GGPPSs from red algae and the green lineages during evolution.

Geranylgeranyl diphosphate（GGPP，C20）是几种重要代谢途径共有的关键代谢中间体，包括类胡萝卜素的生物合成，叶绿素和生育酚的植醇侧链以及赤霉素等二萜。在植物中，GGPP的生物合成是由GGPP合成酶（GGPPS）催化的，其中有些也产生香叶基二磷酸香叶酯（C10）作为其副产物。尽管GGPP作为植物生长，发育和适应所必需的新陈代谢中心发挥了关键作用，但是关于GGPPS在陆地植物甚至藻类中对GGPP的供应的研究很少。在这里，我们报告了潮间带红色藻类海藻Bangia fuscopurpurea的GGPPS（BfGGPPS）的克隆和功能表征。我们的体内和体外分析共同证明，BfGGPPS是真正的GGPPS，它产生GGPP作为其唯一产品。通过酵母双杂交测定，BfGGPPS揭示了其与假定的八氢番茄红素合酶（类胡萝卜素生物合成的进入酶）的相互作用，表明可能通过红藻中的蛋白质-蛋白质相互作用调节代谢通量的机制。我们的系统发育分析表明，在进化过程中，GGPPS与红藻和绿谱系存在早期差异。