Structure of a cereal purple acid phytase provides new insights to phytate degradation in plants

Faba-Rodriguez, Raquel, Gu, Yinghong ORCID:, Salmon, Melissa, Dionisio, Giuseppe, Brinch-Pedersen, Henrik A., Brearley, Charles A. ORCID: and Hemmings, Andrew M. ORCID: (2022) Structure of a cereal purple acid phytase provides new insights to phytate degradation in plants. Plant Communications, 3 (2). ISSN 2590-3462

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Grain phytate, a mixed metal ion salt of inositol hexakisphosphate, accounts for 60%–80% of stored phosphorus in plants and is a potent antinutrient of non-ruminant animals including humans. Through neofunctionalization of purple acid phytases (PAPhy), some cereals such as wheat and rye have acquired particularly high mature grain phytase activity. As PAPhy activity supplies phosphate, liberates metal ions necessary for seedling emergence, and obviates antinutrient effects of phytate, its manipulation and control are targeted crop traits. Here we show the X-ray crystal structure of the b2 isoform of wheat PAPhy induced during germination. This high-resolution crystal structure suggests a model for phytate recognition that, validated by molecular dynamics simulations, implicates elements of two sequence inserts (termed PAPhy motifs) relative to a canonical metallophosphoesterase (MPE) domain in forming phytate-specific substrate specificity pockets. These motifs are well conserved in PAPhys from monocot cereals, enzymes which are characterized by high specificity for phytate. Tested by mutagenesis, residues His229 in PAPhy motif 4 and Lys410 in the MPE domain, both conserved in PAPhys, are found to strongly influence phytase activity. These results explain the observed phytase activity of cereal PAPhys and open the way to the rational engineering of phytase activity in planta.

Item Type: Article
Additional Information: Funding Information: This work was funded by the UK Biotechnology and Biological Sciences Research Council and AB Vista Ltd. through IPA award BB/M022978/1, and by the Danish Ministry of Food, Agriculture and Fisheries (grant no. 3304-FVFP-08-M-07-01).
Uncontrolled Keywords: x-ray crystallography,purple acid phytase,stereospecificity,wheat,plant science,biochemistry,biotechnology,cell biology,molecular biology ,/dk/atira/pure/subjectarea/asjc/1100/1110
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > School of Chemistry
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Depositing User: LivePure Connector
Date Deposited: 22 Feb 2022 10:30
Last Modified: 23 Oct 2022 03:34
DOI: 10.1016/j.xplc.2022.100305

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