2-C-methylerythritol 4-phosphate

2-C-Methylerythritol 4-phosphate (MEP) is an intermediate compound in the non-mevalonate pathway (also known as the MEP pathway or 1-deoxy-D-xylulose-5-phosphate pathway) of isoprenoid biosynthesis. This pathway is an alternative to the mevalonate pathway and is found in many bacteria, algae, and plants.

Structure and Properties

2-C-Methylerythritol 4-phosphate is a phosphorylated sugar alcohol. Its chemical formula is C5H11O6P, and it contains a phosphate group attached to the fourth carbon of the 2-C-methylerythritol backbone. The presence of the phosphate group makes it a charged molecule, which is important for its role in cellular metabolism.

Biosynthesis

The biosynthesis of 2-C-methylerythritol 4-phosphate begins with the condensation of pyruvate and glyceraldehyde 3-phosphate to form 1-deoxy-D-xylulose 5-phosphate (DXP). This reaction is catalyzed by the enzyme 1-deoxy-D-xylulose-5-phosphate synthase (DXS). DXP is then converted to MEP by the enzyme 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), also known as MEP synthase.

Role in Isoprenoid Biosynthesis

MEP is a key intermediate in the non-mevalonate pathway, which leads to the production of isoprenoids. Isoprenoids are a diverse class of organic compounds that include terpenes, steroids, and carotenoids. These compounds have various biological functions, including roles in photosynthesis, hormone regulation, and cell membrane structure.

Enzymatic Reactions Involving MEP

After its formation, MEP undergoes several enzymatic transformations:

1. **MEP is converted to 4-diphosphocytidyl-2-C-methylerythritol (CDP-ME)** by the enzyme MEP cytidylyltransferase (IspD). 2. **CDP-ME is then phosphorylated to 4-diphosphocytidyl-2-C-methylerythritol 2-phosphate (CDP-MEP)** by the enzyme CDP-ME kinase (IspE). 3. **CDP-MEP is converted to 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MEcPP)** by the enzyme MEcPP synthase (IspF).

These steps are crucial for the eventual production of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), the building blocks of isoprenoids.

Biological Significance

The non-mevalonate pathway, including the formation of MEP, is essential in many organisms, particularly in pathogenic bacteria and malaria parasites. This makes the enzymes of this pathway potential targets for the development of new antibiotics and antimalarial drugs.

Also see

• Isoprenoid
• Non-mevalonate pathway
• Mevalonate pathway
• 1-deoxy-D-xylulose-5-phosphate
• Isopentenyl pyrophosphate