Enzymes of the chalcone synthase superfamily from plants and microorganisms

植物次生代谢产物如类黄酮（抗紫外线）、花青素（根瘤菌属）、花青素（花色）和抗微生物植物抗毒素都来源于查尔酮合酶（CHS）超家族成员合成的聚酮化合物。这些酶很小（约42 kDa亚基的同源二聚体），但非常复杂的酶，并在单个活性位点催化多步反应。因此，它们为其他多组分聚酮化合物脱氢酶提供了良好的模型，这些多组分聚酮化合物脱氢酶负责生物合成各种有用的天然产物，包括抗生素、免疫抑制剂和抗癌剂。最近的结构和机制的研究CHS和相关酶的酶机制和CHS超家族的生物合成的多功能性的分子基础的见解。芪合酶是芪超家族的另一个代表性成员，由于其具有抗真菌活性和许多有益健康的作用，在转基因作物的开发中引起了广泛的关注。STS-催化的环化反应，使用未开发的生物有机化学方法的机制研究将提供急需的洞察力，应该证明有价值的聚酮化合物的生物合成，通过代谢工程的操作。已经在进行的是对来自蓝细菌、固氮细菌、苔藓和原始植物马尾草的类似CHS的酶的研究。这些研究结果将有助于更好地了解植物和微生物中酶家族的进化和代谢途径。最后，花药特异性CHS的苔藓同源物可以提供深入了解植物雄性育性的过程。

Plant secondary metabolites such as flavonoids (UV protection), isoflavonoids (Rhizobium nodulation), anthocyanins (floral color), and antimicrobial phytoalexins are all derived from polyketides synthesized by the members of chalcone synthase (CHS) superfamily. These enzymes are small (homodimer of ~42 kDa subunits), yet remarkably complex enzymes and catalyze multiple-step reactions at a single active site. Thus, they provide a good model for other multi-component polyketide synthases, which are responsible for biosynthesis of a variety of useful natural products including antibiotics, immunosuppressants and anticancer agents. Recent structural and mechanistic studies on CHS and related enzymes have yielded insights into enzyme mechanisms and the molecular basis of biosynthetic versatility of the CHS superfamily. Stilbene synthase, another representative member of the superfamily, has attracted much attention in transgenic crop development due to the antifungal activity and a number of beneficial health effects of stilbenes. The proposed mechanistic study on the STS-catalyzed cyclization reaction using unexplored bioorganic chemical approaches will provide much needed insight that should prove valuable in the manipulation of polyketide biosynthesis through metabolic engineering. Already underway are studies on CHS-like enzymes from a cyanobacterium, a nitrogen-fixing bacterium, a moss, and a primitive plant, horsetail. Results obtained from these studies will lead to a better understanding of the evolution of enzyme family and metabolic pathway in plants and microorganisms. Finally, the moss homologue of anther-specific CHSs may provide insights into the poorly understood process of plant male fertility.