Ent-Copalyl diphosphate synthase

Ent-Copalyl diphosphate synthase (CPS) is an enzyme that plays a crucial role in the biosynthesis of gibberellins, a class of diterpenoid plant hormones involved in regulating plant growth and development. This enzyme catalyzes the cyclization of geranylgeranyl diphosphate (GGPP) to form ent-copalyl diphosphate (ent-CPP), a key intermediate in the gibberellin biosynthetic pathway.

Function

Ent-Copalyl diphosphate synthase is integral to the gibberellin biosynthesis pathway, which is essential for various physiological processes in plants, including seed germination, stem elongation, leaf expansion, and flowering. The enzyme's activity is highly regulated within the plant, ensuring that gibberellin levels are maintained within optimal ranges to support growth and development.

Structure

The structure of ent-Copalyl diphosphate synthase is characterized by a conserved domain architecture that is typical of class II diterpene cyclases. This includes a catalytic domain that facilitates the cyclization of GGPP to ent-CPP. The active site of the enzyme is often buried within the protein, accessible only through a narrow channel that allows the substrate to enter and the product to exit.

Mechanism

The mechanism of action of ent-Copalyl diphosphate synthase involves the ionization of the diphosphate moiety of GGPP, followed by a series of conformational changes and cyclization reactions. This process results in the formation of ent-CPP, which is then further processed by other enzymes in the gibberellin biosynthesis pathway to produce various gibberellin compounds.

Genetic Regulation

The expression of the gene encoding ent-Copalyl diphosphate synthase is tightly regulated by various environmental and developmental signals. This ensures that gibberellin biosynthesis is modulated according to the plant's growth needs and environmental conditions.

Evolution

Ent-Copalyl diphosphate synthase belongs to a larger family of terpene synthases that have evolved diverse functions across different plant species. Comparative genomic and phylogenetic analyses have provided insights into the evolutionary history of this enzyme and its role in the diversification of plant secondary metabolism.

Applications

Understanding the function and regulation of ent-Copalyl diphosphate synthase has significant implications for agriculture and horticulture. Manipulation of this enzyme's activity could lead to the development of crops with improved growth characteristics, increased resistance to environmental stresses, and enhanced nutritional value.

See Also

• Gibberellin
• Diterpenoid
• Plant hormone
• Geranylgeranyl diphosphate