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KMID : 0545120010110061066
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Journal of Microbiology and Biotechnology
2001 Volume.11 No. 6 p.1066 ~ p.1070
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Expression of the Aspergillus niger var. awamori Phytase Gene in Pichia pastoris, and Comparison of Biological Properties
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Choi, Jae Mun
Kim, Doo Sang/Yang, Moon Sick/Kim, Hyung Rak/Kim, Jae Ho
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Abstract
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The PhyA gene, encoding myo-inositol hexakisphosphate phosphohydrolase in Aspergillus niger var. awamori (wild-type), was cloned and sequenced. The cDNA was overexpressed by a multicopy gene expression system in Pichia pastoris KM71. Recombinant, wild-type, and commercial phytase from Aspergillus ficuum NRRL 3135 (Natuphos) were purified. The PhyA gene of Aspergillus niger var awamori showed perfect homology to the phytase of Aspergillus ficcum and 97% homology to A. niger var awamori (L02421). Wild-type phytase was highly glycosylated and more thermostable than the other two, while deglycosylated forms of three phytases showed identical molecular weight, 50 kDa. After heating at 80℃, wild-type, commercial, and recombinant phytases retained 57%, 32%, and 8% of their original activities, respectively. In conclusion, glycosylation plays a key role in the thermostability of phytase and its enzymatic characterization.
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