isopentenyl diphosphate biosynthetic process, methylerythritol 4-phosphate pathway

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of isopentenyl diphosphate by the mevalonate-independent pathway. Isopentenyl diphosphate (IPP) is the fundamental unit in isoprenoid biosynthesis and is biosynthesized from pyruvate and glyceraldehyde 3-phosphate via intermediates, including 1-deoxy-D-xylulose 5-phosphate. [GOC:go_curators, MetaCyc:NONMEVIPP-PWY, PMID:18948055]

The methylerythritol 4-phosphate (MEP) pathway, also known as the non-mevalonate pathway, is a metabolic route that synthesizes isopentenyl diphosphate (IPP), a precursor to isoprenoids. This pathway is found in bacteria, plants, and some protists, but not in animals.

The MEP pathway starts with pyruvate and glyceraldehyde 3-phosphate, which are condensed to form 1-deoxy-D-xylulose 5-phosphate (DXP). DXP is then converted to MEP in a series of enzymatic steps. MEP is then phosphorylated to form methylerythritol 4-phosphate cytidyl diphosphate (CDP-MEP). CDP-MEP is then converted to 4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) through a complex series of reactions. Finally, HMBPP is decarboxylated to form IPP, which is then used in the biosynthesis of a wide variety of isoprenoids.

**Detailed steps in the MEP pathway:**

1. **Formation of 1-deoxy-D-xylulose 5-phosphate (DXP):** Pyruvate and glyceraldehyde 3-phosphate are condensed by the enzyme DXP synthase to form DXP.

2. **Formation of methylerythritol 4-phosphate (MEP):** DXP is then converted to MEP in a series of steps catalyzed by the enzymes DXP reductoisomerase, MEP synthase, and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase.

3. **Formation of methylerythritol 4-phosphate cytidyl diphosphate (CDP-MEP):** MEP is phosphorylated by MEP kinase to form MEP 4-phosphate. MEP 4-phosphate is then reacted with CTP (cytidine triphosphate) by CDP-MEP synthase to form CDP-MEP.

4. **Formation of 4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP):** CDP-MEP is converted to HMBPP through a series of complex reactions catalyzed by the enzymes 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase and HMBPP synthase.

5. **Formation of isopentenyl diphosphate (IPP):** HMBPP is decarboxylated by the enzyme HMBPP reductase to form IPP.

**Importance of the MEP pathway:**

The MEP pathway is essential for the biosynthesis of isoprenoids, which are a diverse class of organic molecules with a wide range of biological functions. These functions include:

* **Hormone biosynthesis:** Many plant hormones, such as gibberellins, are isoprenoids.
* **Pigmentation:** Carotenoids, which are responsible for the yellow, orange, and red colors of many plants and animals, are isoprenoids.
* **Membrane structure:** Isoprenoids are important components of cell membranes.
* **Secondary metabolism:** Isoprenoids are involved in the production of a variety of secondary metabolites, such as terpenoids, steroids, and rubber.

**Applications of the MEP pathway:**

The MEP pathway has several potential applications, including:

* **Biotechnology:** The MEP pathway can be used to produce isoprenoids for use in various industries, such as pharmaceuticals, cosmetics, and food.
* **Agriculture:** The MEP pathway can be manipulated to improve the yield and quality of crops.
* **Medicine:** The MEP pathway is a potential target for the development of new drugs to treat diseases such as malaria and cancer.'
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Proteins (5)

Compounds (19)