tailieunhanh - Báo cáo khoa học: The tandemly repeated domains of a b-propeller phytase act synergistically to increase catalytic efficiency

b-Propeller phytases (BPPs) with tandemly repeated domains are abundant in nature. Previous studies have shown that the intact domain is responsi-ble for phytate hydrolysis, but the function of the other domain is rela-tively unknown. In this study, a new dual-domain BPP (PhyH) from Bacillussp. | IFEBS Journal The tandemly repeated domains of a b-propeller phytase act synergistically to increase catalytic efficiency Zhongyuan Li Huoqing Huang Peilong Yang Tiezheng Yuan Pengjun Shi Junqi Zhao Kun Meng and Bin Yao Key Laboratory for Feed Biotechnology of the Ministry of Agriculture Feed Research Institute Chinese Academy of AgriculturalSciences Beijing China Keywords dual domain fusion protein phytate synergistic catalysis b-propeller phytase Correspondence B. Yao Key Laboratory for Feed Biotechnology of the Ministry of Agriculture Feed Research Institute Chinese Academy of AgriculturalSciences No. 12 Zhongguancun South Street Beijing 100081 China Fax 86 10 8210 6054 Tel 86 10 8210 6053 E-mail yaobin@ yaobin@ Z. Li and H. Huang contributed equally to this paper Received 10 March 2011 revised 20 June 2011 accepted 23 June 2011 doi b-Propeller phytases BPPs with tandemly repeated domains are abundant in nature. Previous studies have shown that the intact domain is responsible for phytate hydrolysis but the function of the other domain is relatively unknown. In this study a new dual-domain BPP PhyH from Bacillus sp. HJB17 was identified to contain an incomplete N-terminal BPP domain PhyH-DI residues 41-318 and a typical BPP domain PhyH-DII residues 319-644 at the C-terminus. Purified recombinant PhyH and PhyH-DII required Ca2 for phytase activity showed activity at low temperatures 0-35 C and pH and remained active at 37 C after incubation at 60 C and pH . Compared with PhyH-DII PhyH is catalytically more active against phytate catalytic constant versus s 1 which indicates the importance of PhyH-DI in phytate degradation. PhyH-DI was found to hydrolyze phytate intermediate D-Ins 1 4 5 6 P4 and to act synergistically a increase in phosphate release with PhyH-DII other BpPs PhyP and 168PhyA and a histidine acid phosphatase. Furthermore fusion of PhyH-DI with .