title: Novel low-temperature-active phytase from Erwinia carotovora var.carotovota ACCC 10276.
abstract: A phytase with high activity at low temperatures has great potential for feed applications, especially in aquaculture. Therefore, this study used a degenerate PCR and TAIL PCR to clone a phytase gene from Erwinia carotovora var. carotovota, the cause of soft rot of vegetables in the ground or during cold storage. The full-length 2.5-kb fragment included an open reading frame of 1,302 bp and encoded a putative phytase of 45.3 kDa with a 50% amino acid identity to the Klebsiella pneumoniae phytase. The phytase contained the active site RHGXRXP and HD sequence motifs that are typical of histidine acid phosphatases. The enzyme was expressed in Escherichia coli, purified, and displayed the following characteristics: a high catalytic activity at low temperatures (retaining over 24% activity at 5 degrees C) and remarkably thermal lability (losing >96% activity after incubation at 60 degrees C for 2 min). The optimal phytase activity occurred at pH 5.5 and approximately 40 degrees C, and the enzyme activity rapidly decreased above 40 degrees C. When compared with mesophilic counterparts, the phytase not only exhibited a high activity at a low temperature, but also had a low K(m) and high k(cat). These temperature characteristics and kinetic parameters are consistent with low-temperature-active enzymes. To our knowledge, this would appear to be the first report of a low-temperature-active phytase and its heterogeneous expression.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Huoqing
authors.initials: H
authors.lastname: Huang
authors.forename: Huiying
authors.initials: H
authors.lastname: Luo
authors.forename: Yaru
authors.initials: Y
authors.lastname: Wang
authors.forename: Dawei
authors.initials: D
authors.lastname: Fu
authors.forename: Na
authors.initials: N
authors.lastname: Shao
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D010832:6-Phytase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D003080:Cold Temperature; D004795:Enzyme Stability; D007700:Kinetics; D008969:Molecular Sequence Data; D016973:Pectobacterium carotovorum / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D010832:6-Phytase