4-Hydroxyphenylpyruvate dioxygenase gene

CS-hppdPfW336-PSEFL

Strain: A32

4-hydroxyphenylpyruvate dioxygenase

4-hydroxyphenylpyruvate dioxygenase (HPPD) catalyses the conversion of 4-hydroxyphenylpyruvate to homogentisate which is the aromatic precursor of tocopherol and plastoquinone, which are essential to the photosynthetic transport chain and antioxidative systems. This reaction involves decarboxylation, substituent migration and aromatic oxygenation in a single catalytic cycle.

To enhance the protein's tolerance against HPPD inhibitors a point mutation was introduced into the coding sequence such that a replacement of the amino acid glycine with a tryptophane at position 336 was introduced, as described by  Boudec et al. (2001)

In plants inhibition of HPPD affects the formation of homogentisic acid, which is a key precursor for the biosynthesis of both tocopherols (vitamin E) and plastoquinone, a critical co-factor in the formation of carotenoids, which protect chlorophyll in plants from being destroyed by sunlight. If this happens,the plants turn white without deformation due to complete loss of chlorophyll, and the plant dies.