1sp8
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4-Hydroxyphenylpyruvate Dioxygenase
OverviewOverview
The transformation of 4-hydroxyphenylpyruvate to homogentisate, catalyzed, by 4-hydroxyphenylpyruvate dioxygenase (HPPD), plays an important role in, degrading aromatic amino acids. As the reaction product homogentisate, serves as aromatic precursor for prenylquinone synthesis in plants, the, enzyme is an interesting target for herbicides. In this study we report, the first x-ray structures of the plant HPPDs of Zea mays and Arabidopsis, in their substrate-free form at 2.0 A and 3.0 A resolution, respectively., Previous biochemical characterizations have demonstrated that eukaryotic, enzymes behave as homodimers in contrast to prokaryotic HPPDs, which are, homotetramers. Plant and bacterial enzymes share the overall fold but use, orthogonal surfaces for oligomerization. In addition, comparison of both, structures provides direct evidence that the C-terminal helix gates, substrate access to the active site around a nonheme ferrous iron center., In the Z. mays HPPD structure this helix packs into the active site, sequestering it completely from the solvent. In contrast, in the, Arabidopsis structure this helix tilted by about 60 degrees into the, solvent and leaves the active site fully accessible. By elucidating the, structure of plant HPPD enzymes we aim to provide a structural basis for, the development of new herbicides.
About this StructureAbout this Structure
1SP8 is a Protein complex structure of sequences from Zea mays with FE2 as ligand. Full crystallographic information is available from OCA.
ReferenceReference
The crystal structures of Zea mays and Arabidopsis 4-hydroxyphenylpyruvate dioxygenase., Fritze IM, Linden L, Freigang J, Auerbach G, Huber R, Steinbacher S, Plant Physiol. 2004 Apr;134(4):1388-400. PMID:15084729
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