Expression, purification and characterization of a phyA(m)-phyCs fusion phytase.
The phyA(m) gene encoding acid phytase and optimized neutral phytase phyCs gene were inserted into expression vector pPIC9K in correct orientation and transformed into Pichia pastoris in order to expand the pH profile of phytase and decrease the cost of production. The fusion phytase phyA(m)-phyCs gene was successfully overexpressed in P. pastoris as an active and extracellular phytase. The yield of total extracellular fusion phytase activity is (25.4+/-0.53) U/ml at the flask scale and (159.1+/-2.92) U/ml for high cell-density fermentation, respectively. Purified fusion phytase exhibits an optimal temperature at 55 degrees C and an optimal pH at 5.5~6.0 and its relative activity remains at a relatively high level of above 70% in the range of pH 2.0 to 7.0. About 51% to 63% of its original activity remains after incubation at 75 degrees C to 95 degrees C for 10 min. Due to heavy glycosylation, the expressed fusion phytase shows a broad and diffuse band in SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). After deglycosylation by endoglycosidase H (EndoH(f)), the enzyme has an apparent molecular size of 95 kDa. The characterization of the fusion phytase was compared with those of phyCs and phyA(m).
Zou
Li-Kou
LK
College of Life Science, Bioengineering Research Center for Animal Disease Prevention and Control, Sichuan University, Chengdu, China. zoulkcn@hotmail.com
Wang
Hong-Ning
HN
Pan
Xin
X
Tian
Guo-Bao
GB
Xie
Zi-Wen
ZW
Wu
Qi
Q
Chen
Hui
H
Xie
Tao
T
Yang
Zhi-Rong
ZR
D010832:6-Phytase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D005285:Fermentation; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D010843:Pichia / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000302:isolation & purification
D011993:Recombinant Fusion Proteins; D010832:6-Phytase