Metabolic Pathways and Key Enzyme of Bioisoprene

There are two naturally occurring pathways for isoprene biosynthesis the meval-onate (MVA) pathway and the methylerythritol 4-phosphate (MEP) pathway 

The MEP pathway is present in eubacteria, green algae, and chloroplasts of higher plants [13,18]. DMAPP biosynthesis starts with the condensation of pyruvate (Pyr) and glyceraldehyde-3-phosphate (G3P) to form l-deoxy-o-xylulose-5-phosphate (DXP). DXP is produced by the first enzyme, DXP synthase, and is converted to MEP in a single step by intramolecular rearrangement and reduction via DXP reductoisomerase. MEP is then transformed to HMBPP via four reaction steps. IPP and its isomer DMAPP are finally obtained from HMBPP by HMBPP reductase. The formations of DXP and MEP are believed to be the committed steps in the MEP pathway for the isoprenoid production. The positive correlation of the transcript of DXP synthase or DXP reductoisomerase with terpenoid production has been observed [19]. 

2-phospho-glycerate AcCoA acetyl coenzyme A Pyr pyruvate PEP phosphoenol-pyruvate SUCC-CoA succinyl coenzyme A SUCC succinate RIB-5P ribulose 5-phosphate RIBO-5P ribose 5-phosphate  

XYL-5P xylulose 5-phosphate S7P sedo-heptulose 7-phosphate E-4P erythrose 4-phosphate COj carbon dioxide IPP isopentenyl pyrophosphate DMAPP dimethylallyl pyrophosphate AcP acetyl-P KDPG 2-keto- 

3- deoxy-6-phosphogluconate DXP 1-deoxy-D-xylulose-5-phosphate MEP methylerythritol 

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