Towards engineering increased pantothenate (vitamin B5) levels in plants
Towards engineering increased pantothenate (vitamin B5) levels in plants
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DOI：
10.1007/s11103-008-9386-5
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发表时间：
2008-11-01
影响因子：
5.1
通讯作者：
Smith, Alison G.
中科院分区：
文献类型：
--
作者：
Chakauya, Ereck;Coxon, Katy M.;Smith, Alison G.
泛酸（维生素B-5）是辅酶A和酰基载体蛋白的40-磷酸泛酰巯基乙胺部分的前体。它是由植物和微生物从头制造的，但却是动物的饮食要求。泛酸生物合成途径在细菌中已被充分建立，包括分别由panB、panD、panC和panE基因编码的酮泛解酸羟甲基转移酶（KPHMT）、L-天冬氨酸-α-脱羧酶（ADC）、泛酸合成酶（PS）和酮泛解酸还原酶（KPR）催化的四个酶促反应。在高等植物中，编码第一种（KPHMT）和最后一种（PS）酶的基因已经在几种植物物种中被鉴定和表征。在商业上，泛酸是化学合成的，用于维生素补充剂、饲料添加剂和化妆品。生物转化是一种有吸引力的替代生产系统，它可以避免昂贵的分离外消旋中间体的过程。我们探索了在植物中操纵泛酸生物合成的可能性。转基因油菜（Brassica napus）品系的产生，其中E。coliKPHMT和PS基因在强组成型CaMV 35 SS启动子下表达。PS转基因株系的泛酸水平无明显变化。相比之下，表达KPHMT的植物在叶、花、长角果和种子中具有升高的泛酸水平，与野生型植物相比在1.5-2.5倍的范围内增加。种子含有最高的维生素含量，表明它们可能是生产目的的理想目标。
Pantothenate (vitamin B-5) is the precursor of the 40-phosphopantetheine moiety of coenzyme A and acyl-carrier protein. It is made by plants and microorganisms de novo, but is a dietary requirement for animals. The pantothenate biosynthetic pathway is well-established in bacteria, comprising four enzymic reactions catalysed by ketopantoate hydroxymethyltransferase (KPHMT), L-aspartate-alpha-decarboxylase (ADC), pantothenate synthetase (PS) and ketopantoate reductase (KPR) encoded by panB, panD, panC and panE genes, respectively. In higher plants, the genes encoding the first (KPHMT) and last (PS) enzymes have been identified and characterised in several plant species. Commercially, pantothenate is chemically synthesised and used in vitamin supplements, feed additives and cosmetics. Biotransformation is an attractive alternative production system that would circumvent the expensive procedures of separating racemic intermediates. We explored the possibility of manipulating pantothenate biosynthesis in plants. Transgenic oilseed rape (Brassica napus) lines were generated in which the E. coli KPHMT and PS genes were expressed under a strong constitutive CaMV35SS promoter. No significant change of pantothenate levels in PS transgenic lines was observed. In contrast plants expressing KPHMT had elevated pantothenate levels in leaves, flowers siliques and seed in the range of 1.5-2.5 fold increase compared to the wild type plant. Seeds contained the highest vitamin content, indicating that they might be the ideal target for production purposes.