Yokoyama Ryo, Maeda Hiroshi A
Department of Botany University of Wisconsin-Madison Madison Wisconsin USA.
Central Metabolism Max Planck Institute of Molecular Plant Physiology Potsdam Germany.
Plant Direct. 2025 Jan 21;9(1):e70037. doi: 10.1002/pld3.70037. eCollection 2025 Jan.
The plant shikimate pathway directs a significant portion of photosynthetically assimilated carbon into the downstream biosynthetic pathways of aromatic amino acids (AAA) and aromatic natural products. 3-Deoxy-d--heptulosonate 7-phosphate (DAHP) synthase (hereafter DHS) catalyzes the first step of the shikimate pathway, playing a critical role in controlling the carbon flux from central carbon metabolism into the AAA biosynthesis. Previous biochemical studies suggested the presence of manganese- and cobalt-dependent DHS enzymes (DHS-Mn and DHS-Co, respectively) in various plant species. Unlike well-studied DHS-Mn, however, the identity of DHS-Co is still unknown. Here, we show that all three DHS isoforms of exhibit both DHS-Mn and DHS-Co activities in vitro. A phylogenetic analysis of various DHS orthologs and related sequences showed that Arabidopsis 3-deoxy-D--octulosonate-8-phosphate synthase (KDOPS) proteins were closely related to microbial Type I DHSs. Despite their sequence similarity, these Arabidopsis KDOPS proteins showed no DHS activity. Meanwhile, optimization of the DHS assay conditions led to the successful detection of DHS-Co activity from Arabidopsis DHS recombinant proteins. Compared with DHS-Mn, DHS-Co activity displayed the same redox dependency but distinct optimal pH and cofactor sensitivity. Our work provides biochemical evidence that the DHS isoforms of Arabidopsis possess DHS-Co activity.
植物莽草酸途径将很大一部分光合同化碳导向芳香族氨基酸（AAA）和芳香族天然产物的下游生物合成途径。3-脱氧-D-阿拉伯庚酮糖酸-7-磷酸（DAHP）合酶（以下简称DHS）催化莽草酸途径的第一步，在控制从中心碳代谢到AAA生物合成的碳通量中起关键作用。先前的生化研究表明，在各种植物物种中存在锰依赖性和钴依赖性DHS酶（分别为DHS-Mn和DHS-Co）。然而，与研究充分的DHS-Mn不同，DHS-Co的身份仍然未知。在这里，我们表明 的所有三种DHS同工型在体外均表现出DHS-Mn和DHS-Co活性。对各种DHS直系同源物和相关序列的系统发育分析表明，拟南芥3-脱氧-D-阿拉伯辛酮糖酸-8-磷酸合酶（KDOPS）蛋白与微生物I型DHS密切相关。尽管它们的序列相似，但这些拟南芥KDOPS蛋白没有显示出DHS活性。同时，DHS检测条件的优化导致成功检测到拟南芥DHS重组蛋白的DHS-Co活性。与DHS-Mn相比，DHS-Co活性表现出相同的氧化还原依赖性，但具有不同的最佳pH值和辅因子敏感性。我们的工作提供了生化证据，证明拟南芥的DHS同工型具有DHS-Co活性。
