Planta Med 2008; 74 - L29
DOI: 10.1055/s-0028-1083874

The methylerythritol phosphate pathway, a novel metabolic route towards the isoprene units in bacteria and plant plastids

M Rohmer 1
  • 1Université Louis Pasteur/CNRS, Institut de Chimie, 4 rue Blaise Pascal, 67070 Strasbourg Cedex, France

Two biosynthetic pathways are contributing to the formation of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the universal precursors of isoprene units. The mevalonate (MVA) pathway, known for decades, is found in animals, fungi and in the cytoplasm of higher plants [1–4]. The methylerythritol phosphate (MEP) pathway was discovered more recently and is present in most bacteria and in the plastids of phototrophic organisms. Its full elucidation resulted from a combination of chemical and molecular biology methods [5–8].

In higher plants, several features opened unexplored ways for the regulation of isoprenoid biosynthesis. i) In the MEP pathway, the last enzyme encoded by the lytB/ispH gene is a two products enzyme, yielding either IPP or DMAPP. ii) In plants, the MEP pathway is coupled to photosynthesis: the reduction performed by the [Fe4S4] cluster of GcpE/IspG may be performed in the presence of two associated reducing systems: ferredoxin/photosystems I and II (thylakoids) in the presence of light, or ferredoxin/ferredoxin reductase in the dark [9]. iii) The simultaneous presence in plants of the cytoplasmic MVA pathway and of the plastidial MEP pathway allows cross-talk and intermediate exchanges between the two cell compartments [10–11].

Acknowledgements: This work partly supported by the ANR grant ANR-05-BLAN-0217–02

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