PhnW-PhnX Pathway in Dinoflagellates Not Functional to Utilize Extracellular Phosphonates
PhnW-PhnX Pathway in Dinoflagellates Not Functional to Utilize Extracellular Phosphonates
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DOI：
10.3389/fmars.2015.00120
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发表时间：
2016-01-01
影响因子：
3.7
通讯作者：
Lin, Senjie
中科院分区：
文献类型：
--
作者：
Cui, Yudong;Lin, Xin;Lin, Senjie
磷(P)是海洋浮游植物必需的营养物质，但其首选形式，溶解无机磷（DIP），往往局限于海洋的光带。许多浮游植物物种已经发展出利用溶解有机磷（DOP）的能力，如磷酸酯或膦酸盐。磷酸盐以稳定的C-P键为特征，已知其利用依赖于细菌中的C-P裂解酶途径或C-P水解酶途径。在本研究中，我们通过转录组学分析，检测了Karlodinium veneficum和其他鞭毛藻中C-P水解酶途径酶PhnW和PhnX的编码基因。然而，我们发现在抗生素治疗的条件下，这些鞭毛藻无法利用海洋中可能占主导地位的膦酸盐，2-氨基乙基膦酸（2-AEP）。因此，我们的RT-qPCR和蛋白质组学分析显示，在2-AEP上生长的veneficum在转录和翻译水平上都没有上调PhnW和PhnX。然而，与膦酸盐生物合成和利用有关的基因在鞭毛藻中广泛存在。综上所述，我们的研究结果表明，鞭毛藻中的PhnW-PhnX通路可能用于细胞内磷酸盐代谢，而不是清除环境中的磷酸盐。
Phosphorus (P) is an essential nutrient for marine phytoplankton but its preferred form, dissolved inorganic phosphorus (DIP), is often limited in the euphotic zone of the ocean. Many phytoplankton species have developed the ability to utilize dissolved organic phosphorus (DOP) such as phosphoesters or phosphonates. Phosphonates are characterized by the stable C-P bond and its utilization is known to rely on either a C-P lyase pathway or C-P hydrolase pathways in bacteria. In this study by transcriptomic analysis we detected the genes encoding the C-P hydrolase pathway enzymes PhnW and PhnX in Karlodinium veneficum and other dinoflagellates. However, we found that these dinoflagellates are unable to utilize the presumably dominant type of phosphonate in the ocean, 2-aminoethylphosphonic acid (2-AEP), under the antibiotic-treated condition. In accordance, our RT-qPCR and proteomic analyses of K. veneficum grown on 2-AEP showed no up-regulation of PhnW and PhnX at both transcriptional and translational levels. Nevertheless, the genes related to phosphonate biosynthesis and utilization were widely found in dinoflagellates. Taken together our results suggest that the PhnW-PhnX pathway in dinoflagellates may serve for intracellular phosphonate metabolism instead of scavenging environmental phosphonates.