9-cis-epoxycarotenoid dioxygenase

9-cis-epoxycarotenoid dioxygenase

Structure of 9-cis-epoxycarotenoid dioxygenase

9-cis-epoxycarotenoid dioxygenase (NCED) is an enzyme that plays a crucial role in the biosynthesis of the plant hormone abscisic acid (ABA). This enzyme is involved in the oxidative cleavage of 9-cis-epoxycarotenoids, which are carotenoid precursors of ABA.

Function

9-cis-epoxycarotenoid dioxygenase catalyzes the cleavage of 9-cis-epoxycarotenoids to produce xanthoxin, a direct precursor of abscisic acid. This reaction is a key regulatory step in the biosynthesis of ABA, which is an important hormone involved in plant responses to stress, such as drought and high salinity, as well as in the regulation of seed dormancy and germination.

Structure

The structure of 9-cis-epoxycarotenoid dioxygenase has been elucidated through X-ray crystallography. The enzyme typically consists of a conserved domain that binds to the carotenoid substrate and facilitates its cleavage. The active site of the enzyme contains metal ions that are essential for its catalytic activity.

Biological significance

The activity of 9-cis-epoxycarotenoid dioxygenase is crucial for the regulation of abscisic acid levels in plants. ABA is a key hormone that mediates various physiological processes, including stomatal closure, seed maturation, and adaptation to environmental stresses. By controlling the production of ABA, NCED enzymes help plants to survive and adapt to changing environmental conditions.

Genetic studies

Genetic studies have identified multiple genes encoding 9-cis-epoxycarotenoid dioxygenase in various plant species. These genes are often differentially expressed in response to environmental stimuli, indicating their role in stress adaptation. Mutations in NCED genes can lead to altered ABA levels and affect plant growth and development.

Applications

Understanding the function and regulation of 9-cis-epoxycarotenoid dioxygenase has applications in agriculture and biotechnology. By manipulating the expression of NCED genes, it is possible to develop crops with improved stress tolerance and water-use efficiency. This can lead to enhanced crop productivity in arid and saline environments.

Related pages

• Abscisic acid
• Carotenoid
• Plant hormone
• X-ray crystallography

9-cis-epoxycarotenoid dioxygenase

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