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

作　　者：Raquel Faba-Rodriguez Yinghong Gu Melissa Salmon Giuseppe Dionisio Henrik Brinch-Pedersen Charles A.Brearley Andrew M.Hemmings 

机构地区：[1]School of Chemistry,University of East Anglia,Norwich Research Park,Norwich NR47TJ,UK [2]School of Biological Sciences,University of East Anglia,Norwich Research Park,Norwich NR47TJ,UK [3]Department of Agroecology,Research Center Flakkebjerg,Aarhus University,4200 Slagelse,Denmark [4]College of Food Science and Technology,Shanghai Ocean University,Shanghai 201306,China

出　　处：《Plant Communications》2022年第2期52-61,共10页植物通讯（英文）

基　　金：This work was funded by the UK Biotechnology and Biological Sciences Research Council and AB Vista Ltd.through IPA award BB/M022978/1;the Danish Ministry of Food,Agriculture and Fisheries(grant no.3304-FVFP-08-M-07-01).

摘　　要：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.

关 键 词：wheat purple acid phytase X-ray crystallography STEREOSPECIFICITY 

分 类 号：Q946[生物学—植物学]