Abstract

Phytate is the major form of phosphorus storage in plant seeds and the soil organic phosphorus. The phytase is a class of enzymes which catalyzes the hydrolysis of phytate and release free orthophosphoric acid. Motifs provide insight into protein structure, function and evolution. 39 fingerprint motifs were obtained in phytases through multiple EM for motif elicitation (MEME) analysis based on 54 whole phytase sequences with an average of 16.6% identity (ranging from 3.9 to 52.5%). The phytase family is classified into seven groups: HAPhys, PAPhys, BPPhys, BPRPhys, PTPhys, ALPhys and APPAs according to the phylogenetic analysis and motif characters. Every phytase group has its typical fingerprint motifs through motif alignment and search tool (MAST) results. Based on the phylogenetic tree and characteristics of phytase motif organisations, BPPhy family has 13 motifs, and is classified into five subgroups, BPPhy I to V. HAPhy with 11 motifs is classified into four subgroups, HAPhyI to IV. PAPhy, BPRPhy, PTPhy and APPAs have four, four, four and six fingerprint motifs, respectively, but no fingerprint motifs are found by MAST for ALPhys. In comparison with known crystal structures, motif fingerprints are relative to key amino acid residues of phytase activity, which make the features of different phytase groups known better based on their primary structures. Among the total of potential 173 phytases gained in 11 plant genomes through MAST, PAPhys are the major phytases, and HAPhys are the minor, and other phytase groups are not found in planta.

Key words: Phytase, fingerprint motif, multiple EM for motif elicitation (MEME), MAST.