In plants and photosynthetic bacteria, the tyrosine degradation pathway is crucial because homogentisate, a tyrosine degradation product, is a precursor for the biosynthesis of photosynthetic pigments, such as quinones or tocophenols. Homogentisate biosynthesis includes a decarboxylation step, a dioxygenation and a rearrangement of the pyruvate sidechain ...
In plants and photosynthetic bacteria, the tyrosine degradation pathway is crucial because homogentisate, a tyrosine degradation product, is a precursor for the biosynthesis of photosynthetic pigments, such as quinones or tocophenols. Homogentisate biosynthesis includes a decarboxylation step, a dioxygenation and a rearrangement of the pyruvate sidechain. This complex reaction is carried out by a single enzyme, the 4-hydroxyphenylpyruvate dioxygenase (HPPD), a non-heme iron dependent enzyme that is active as a homotetramer in bacteria and as a homodimer in plants. Moreover, in humans, a HPPD deficiency is found to be related to tyrosinemia, a rare hereditary disorder of tyrosine catabolism.
Organizational Affiliation:
Institut de Biologie Structurale Jean-Pierre Ebel, CNRS/CEA, Grenoble, France. laurence@cnrs-orleans.fr
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