University of Copenhagen, Faculty of Life Sciences, Department of Plant Biology, Plant Biochemistry Laboratory, VKR Research Centre for Pro-Active Plants, 40 Thorvaldsensvej, DK-1871 Frederiksberg C, Copenhagen, Denmark.
Mol Plant. 2010 Jul;3(4):751-9. doi: 10.1093/mp/ssq020. Epub 2010 May 9.
Epidemiological studies have demonstrated reduced risk of developing cancer upon consumption of diets rich in cruciferous vegetables. This chemoprevention has been largely attributed to the presence of the natural products glucosinolates, particularly the methionine-derived glucoraphanin from broccoli. Improved nutrition by functional foods or health-promoting dietary supplements is an attractive means for prevention of lifestyle-based diseases. Towards this goal, we have engineered the glucoraphanin pathway into tobacco. First, we engineered elongation of the side chain of methionine to produce the key intermediate dihomo-methionine. This process is catalyzed through two cycles in a chain-elongation pathway that takes place partly in the cytosol and partly in the chloroplast. Second, by coupling the five enzymes of the chain-elongation pathway to eight enzymes of the glucosinolate pathway, we show production of glucoraphanin together with other glucosinolates derived from chain-elongated isoleucine and/or leucine. The conversion of methionine to glucoraphanin is obtained via 14 intermediates. Demonstrating the production of the high-value glucoraphanin in a heterologous host has great potential in the food and medicinal industry as a means to generate a stable, rich source of glucoraphanin for the benefit of human health.
流行病学研究表明，摄入富含十字花科蔬菜的饮食可降低癌症风险。这种化学预防作用在很大程度上归因于天然产物硫代葡萄糖苷的存在，特别是来自西兰花的蛋氨酸衍生的萝卜硫素。通过功能性食品或促进健康的膳食补充剂改善营养是预防基于生活方式的疾病的一种有吸引力的方法。为此，我们已经将萝卜硫素途径工程化到烟草中。首先，我们通过两个循环的链延伸途径来延长蛋氨酸的侧链，生成关键中间体双同型蛋氨酸。该过程部分发生在细胞质中，部分发生在叶绿体中。其次，通过将链延伸途径的 5 种酶与硫代葡萄糖苷途径的 8 种酶偶联，我们展示了萝卜硫素以及其他衍生自链延伸异亮氨酸和/或亮氨酸的硫代葡萄糖苷的产生。蛋氨酸转化为萝卜硫素通过 14 个中间产物获得。在异源宿主中生产高价值的萝卜硫素具有巨大的潜力，可以作为一种手段，为人类健康生成稳定、丰富的萝卜硫素来源。
