The Crystal Structures of Zea mays and Arabidopsis 4-Hydroxyphenylpyruvate Dioxygenase

• Published in: Plant physiology (Bethesda) 2004-04, Vol.134 (4), p.1388-1400
• Main Authors: Iris M. Fritze, Lars Linden, Jörg Freigang, Auerbach, Günter, Huber, Robert, Steinbacher, Stefan
• Format: Article
• Language: English
• Subjects: 4-Hydroxyphenylpyruvate Dioxygenase - chemistry; 4-Hydroxyphenylpyruvate Dioxygenase - metabolism; Active sites; Agronomy. Soil science and plant productions; Amino Acid Sequence; Amino acids; Arabidopsis - chemistry; Arabidopsis - enzymology; Arabidopsis - genetics; Atoms; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding Sites - genetics; Binding Sites - physiology; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Cell physiology; Cells, cell elements: structure and function; Cloning, Molecular; Crystal structure; Crystallography, X-Ray; Dimers; DNA, Complementary - chemistry; DNA, Complementary - genetics; Economic plant physiology; Enzymes; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes. Genome; Growth regulators; Herbicides; Ligands; Metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Molecules; Monomers; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); Nutrition. Photosynthesis. Respiration. Metabolism; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Protein Conformation; Proteins; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Solvents; Zea mays - chemistry; Zea mays - enzymology; Zea mays - genetics
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.103.034082

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 Å and 3.0 Å 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° 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.