1-deoxy-D-xylulose-5-phosphate synthase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: D-glyceraldehyde 3-phosphate + H+ + pyruvate = 1-deoxy-D-xylulose 5-phosphate + CO2. [EC:2.2.1.7, RHEA:12605]

1-Deoxy-D-xylulose-5-phosphate synthase (DXPS) catalyzes the first committed step in the biosynthesis of isoprenoids, a diverse class of molecules essential for numerous biological processes. It is a crucial enzyme in the methylerythritol 4-phosphate (MEP) pathway, which is the primary pathway for isoprenoid biosynthesis in plants, bacteria, and some protists.

DXPS catalyzes the condensation of pyruvate and D-glyceraldehyde 3-phosphate (G3P) to form 1-deoxy-D-xylulose 5-phosphate (DXP). This reaction involves a series of steps, including:

1. **Formation of a Schiff base:** DXPS forms a Schiff base with the amino group of a lysine residue in the active site.
2. **Decarboxylation of pyruvate:** The pyruvate molecule is decarboxylated, releasing carbon dioxide.
3. **Aldol condensation:** The decarboxylated pyruvate reacts with G3P in an aldol condensation reaction, forming a six-carbon intermediate.
4. **Hydrolysis of the Schiff base:** The Schiff base is hydrolyzed, releasing the final product, DXP.

The enzyme's active site contains a number of conserved residues that are essential for its catalytic activity, including:

* **Lysine:** The lysine residue forms the Schiff base with pyruvate and is involved in the decarboxylation reaction.
* **Tyrosine:** A tyrosine residue helps to stabilize the intermediate formed during the aldol condensation reaction.
* **Aspartate and Glutamate:** These residues are involved in the proton transfer steps during the reaction.

DXPS is a highly regulated enzyme, with its activity being influenced by a number of factors, including:

* **Substrate availability:** The enzyme's activity is dependent on the availability of its substrates, pyruvate and G3P.
* **Metabolic feedback:** The levels of downstream metabolites, such as isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), can feedback-inhibit DXPS activity.
* **Gene expression:** The expression of the DXPS gene can be regulated by environmental factors, such as light and temperature.

In summary, DXPS plays a vital role in isoprenoid biosynthesis by catalyzing the formation of DXP, the first committed intermediate in the MEP pathway. This reaction is complex and involves a number of steps, with the enzyme's active site containing several conserved residues essential for its catalytic activity. DXPS activity is tightly regulated by various factors, ensuring appropriate levels of isoprenoid biosynthesis in the cell.'
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Proteins (1)

Compounds (4)